OK TF tottsitir tff JVo. Division Range Shelf Received. ..^zhcAsvu?.. 6.7 1 873- PRESENTED TO THE |S Library of the University of California, I 40TH CONGRESS, \ SENATE. ( EEP. COM. 3d Session. ( ) No. 266. IN THE SENATE OF THE UNITED STATES. FEBRUARY 15, 1869. FEBRUARY 25, 1869. Ordered to be printed, and that two thousand additional copies be printed for the use of the Senate. Mr. HOWARD, from the Joint Committee on Ordnance, submitted the following ,, EEPORT. * ' The Joint Committee appointed under the resolution of the Senate and House of Representatives of the 30th of March, 1867, to investigate the purchases, contracts, and experiments of the ordnance department, having completed their labors as far as relates to experiments upon heavy ordnance, submit the following report thereon: Since the war of 1812 there has been a tendency on the part of all nations to increase the size of their artillery, and within the last few years the important change made in systems of defence by the intro- duction of armor-plating, necessitating more powerful engines of attack, has resulted in enormously increasing the -weight and calibres of guns. This increase of calibre early developed a remarkable and puzzling fact, namely, that systems of fabrication which, with small calibres, gave good endurance when applied to large guns, proved to be failures. Elaborate experiments, stretching over a period of years, have been carried on in Europe and America to solve this problem, and many new systems, which in theory promised success, have been successively tried and abandoned; nearly all of them succeeding well in small guns, but failing in large ones, and failing, too, in a manner which apparently increased the complication of the problem a gun frequently enduring over 2,000 rounds, while another, precisely similar, would explode after a few fires ; while guns made of the strongest material seemed generally to prove the weakest when put to the test. No nation at present has guns of large calibre the endurance of which can be estimated with any degree of certainty. The difficulty, serious enough with smooth-bore guns, is greatly increased in rifles, the 30-pounder being the largest rifled gun that has exhibited even comparatively good endurance in this coun- try, while in Europe no more satisfactory result has been obtained. This unreliability of heavy ordnance, from its tendency to rupture, has been heretofore supposed to be attributable wholly to the expan- sive or projectile force of the powder undergoing combustion, and the efforts of inventors have been directed to devising new means the better" to restrain this force, and on failing, it has been common for them to attribute enormous pressure to the gases of the powder in order to account for the bursting of the guns ; but the fallacy of this reasoning is shown by the fact that the pressure of powder has been found to be uniform, as it gives uniform range to the projectile, and at times does not burst a gun made of weaker material than others which have burst 2 EXPERIMENTS ON HEAVY ORDNANCE. when fired with like charges and under like circumstances. Acting upon this mode of reasoning, two means of increasing the strength of the gun so as to restrain the force of the powder have been employed ; the use of stronger material, such as steel and wrought iron, and methods of fabrication which secure a compressing tension in the metal. Both of these means are employed in the English Armstrong, Fraser, Whit- worth, and Blakely guns, while in the Krupp guns of Prussia, the strength of the metal (steel) is alone relied on, and in the Rodman hol- low-cast guns of this government tension is the restraining force chiefly sought. These two principles have been embodied to a greater or less extent in all the various systems in this country and Europe since the solid mode of casting was abandoned in our service for the hollow mode introduced by Eodman for cast-iron guns; since which, in this country, reliance has been placed upon cast iron with initial tension from the mode of cooling the gun, or cast iron banded with wrought iron, as in the Parrott gun. In England the same theory was introduced in the Armstrong and Whitworth guns, using wrought iron, or a combination of wrought iron and steel, in built-up guns, and cast iron, wrought iron, and steel in various combinations, as in the Blakely system. Krupp, of Prussia, has made solid, dense, and homogeneous guns of large calibre of steel alone, yet his very largest guns have been built up also. None of these systems have proved successful in preventing the burst- ing of guns, or giving them uniformly reliable endurance. The com- mittee do not think it necessary to discuss further the various European systems of gun-making. None of them have shown exemption from the rule of failure, and experiments with them on the part of this govern- ment would be of doubtful value. The Rodman system, employing cast iron, has had the merit of cheapness, and when applied to smooth-bore guns has had claimed for it superiority over European sytems, but it must be considered to be equally a failure with the others, especially when applied to rifled guns. The Chief of Ordnance of the navy, in his last report, acknowledges this to be the case. He says: Opinions differ quite as widely in regard to the preferable mode of developing ordnance power, whether it shall be by smooth or rifled bores, by loading at breech or muzzle, made from iron, cast or wrought, or from steel, solid or in connected parts. The relation of mass to velocity is also unsettled. In fact, the question involves the necessity of going back to fundamental principles, and starting thence by well-conducted experiments. It therefore appears that, notwithstanding a series of elaborate experi- ments, extending over a long period of years, and the practical experience of our recent war, the ordnance officers of the government have not yet determined upon even the fundamental principles of their art, and possess no positive knowledge of the problem they have so long sought to solve. Mechanics is an exact science, and ignorance of that branch of it involved in the construction of guns Avould seem to show either want of knowledge of its principles, failure to understand their application, or superficiality of investigation, surprising in men whose minds have been from boyhood trained in the direction of a specialty. Each system of guns introduced in our service has been subjected in proof to tests supposed to demonstrate beyond question its ability to perform the work required of it, but each has failed when submitted to the real test of service. In the operations upon Morris island 22 large guns was the greatest number mounted at one time, yet 50 in all burst during the siege, as is shown by the evidence of General Gillmore. In the attack on Fort Fisher all the Parrott guns in the fleet burst, according to the report of Admiral Porter. By the bursting of five of these guns at the first bombardment 45 persons were killed and wounded, while only 11 were killed or wounded by the projectiles from the enemy's guns EXPERIMENTS ON HEAVY ORDNANCE. 3 during the attack. The battle of Fort Fisher was the only occasion during the war when rifled guns of large calibre were fired rapidly and continuously for a great number of rounds. The failure to discover the weakness of these guns before putting them in the field, or on board ship for actual service, must be attributed to a defect in the system of proof employed. These systems appear to have been comparatively valueless, and to have proven little or nothing re- specting the ability of the gun to perform the work expected of it in battle. The committee cannot learn that any method of proof has been practiced in the army or navy which subjects guns to the tests they must endure when first brought into actual combat, namely, rapid and con- tinuous firing, with intervals only sufficient for loading. Excessive charges have been used and a great number of rounds fired, but no at- tempt has been made to copy upon the proving ground the conditions existing in battle. In the new conditions developed by the rapid and long-continued firing in battle, not present during the slow and careful firing when in process of proof, it would seem must be found the cause of the frequent rupture of the guns. The most important new condition present during rapid fire would seem to be the communication of a greater amount of heat to the bore of the gun, having a tendency, by its expansive force, to aid the powder in effecting a rupture. If the gun be fired rapidly so as to allow little time for the bore to cool between each discharge, it is believed that the heat communicated would exert a powerful expanding force ; while if there should be long intervals between the shots, even if the charges were excessive, sufficient heat to burst the gun might not be communicated to the interior. In reports of ordnance officers, the effect of unequal cooling in inaugurating unfavor- able tensions in a gun cast solid and cooled wholly from the outside is treated at length, and it is shown that fissures and ruptures have resulted from the contraction towards the outside as the gun cooled, and it is stated that three-fifths of the strength of the gun is ex- pended in this manner, leaving only two-fifths to restrain the pressure of the powder. The hollow mode of casting of the Eodnian system, and the band of wrought iron applied to the Parrott gun, were in- tended to utilize this force of contraction, by assisting the strength of the iron to restrain the pressure of the powder. It was afterwards noticed that several of the Eodnian guns casfc hollow, and cooled from the interior, burst in the foundry from the excess of this force of contraction exerted in the opposite direction from that before referred to. If the force with which metals contract when cooled is shown to be so potent as to break the gun from the inside when cooled from the outside, and from the outside when cooled from the interior, it can be seen that if the gun be in a state of tension, which has the tendency to compress the metal of the interior and extend the exterior, the heat afterwards communicated to the surface of the bore by the burning powder, or by friction of the moving charge, would assist the pressure of the powder to break the gun, especially if the gun should be fired a number of rounds in quick succession. This additional force being considered, it may be possible to determine why guns made of the strongest material are more liable to burst than those made of weaker iron, and why the accidents occur most frequently during battle, when the gun is fired more rapidly than at the time of proof, when it is usually fired slowly. Forces known to be sufficient to actu- ally break large masses of iron, spontaneously, as it were, should not be overlooked while treating so intricate a subject as this of heavy guns. Mr. Holley refers to the rupture of a large mass of wrought iron pre- 4 EXPERIMENTS ON HEAVY ORDNANCE. pared by Mr. Mallet, in England, as attributable to " the force of con- traction from the centre toward the exterior as the mass cooled." Such ruptures of large steamboat shafts are frequently noticed, and con- traction of this kind may explain the fissures in large wrought-iron guns which have been noticed, as well as the soft and easily compressed nature of the iron in the interior of the mass of all classes of large guns. The fact that the ordnance officers of the government find it necessary, at this late day, to return to the sudiments of their art and begin their experiments anew, as stated in the report of the Chief of Ordnance of the navy, shows a defect in the system upon which experiments have heretofore been conducted, and in the organization of the ordnance departments, call- ing for a remedy. The difficulty appears to have been two-fold : First, the ordnance officers, knowing their positions secure to them for life, have not felt the incentive to exertion and improvement which stimulates men not in government employ, and they have become attached to routine and to the traditions of their corps, jealous of innovation and new ideas, and slow to adopt improvements. An illustration of this is found in the fact that the late war was fought with muzzle-loading guns, (with the exception of carbines for cavalry,) although a variety of excellent breech-loaders were urged upon the attention of the government con- stantly, and the honor Avas reserved for Prussia, with a weapon inferior to many American inventions, to demonstrate the immeasurable superiority of breech-loading guns. In the second place, these officers, educated to a specialty and proud of their positions, come to look upon themselves as possessing all the knowledge extant upon the subject of ordnance, and regard citizen inventors and mechanics who offer improvements in arms as ignorant and designing persons, and pretentious innovators, who have no claim to consideration. Instead of encouraging the inventive talent of the country, these officers seem to have constantly discouraged it, and many complaints of improper and oppressive treatment have been laid before the committee by persons who have sought to draw the attention of the proper authorities to what were supposed to be vital principles connected with their art. Another difficulty that has retarded progress in the science of ordnance has been the fact that prominent officers have been inventors of arms, and have possessed sufficient influ- ence to secure the adoption arid retention in service of their inventions, frequently without due regard to the question of real merit, and to the prejudice of other and better devices brought forward by citizens, or developed in other countries. A further difficulty, calling for a remedy, lies in the want of co-operation between the war and navy ordnance bureaus. Great diversity exists in the practice of the two branches of the service respecting the arms adopted, and the manner of proving, mounting, and using the same. The calibres, models, chambers and ammunition of the navy guns are entirely unlike those in use in the army. For example, the navy 12-pounder boat howitzer has a calibre of 3.4 inches, while the army 12-pounder guns are of the calibres of 3, 3.2, 3.67, and 3.8 inches. The chamber of the navy gun is of parabolic form, while the army gun either has a cycloidal chamber or none at all. The models of the two guns are entirely different, so that neither could be used on the carriage of the other; the army guns being furnished with trunnions, and the navy gun having, in some cases, the loop and loop-bolt of the old carronade. The system of sighting is also different. A gunner in one arm of the service, without special instruc- tion, could not use a gun belonging to the other; one being grad- uated to seconds of time of the flight of the shot, and the other to degrees of elevation. The navy has 8, 9, 11, and 13-inch smooth EXPERIMENTS ON HEAVY ORDNANCE. 5 bores, while the army guns are of the calibres of 6, 8, 10, and 12 inches. In the guns of the two branches of the service there is no uniformity, in either rifle or smooth-bore, in the 20 calibres adopted below the calibre of the 32-pounders. It is impossible to use navy ammunition in an army gun or army ammunition in a navy gun. Co-operation between the army and navy while in active service is thus greatly restricted, and in some cases has been entirely prevented. Offensive operations on the part of a joint expedition of the two might be brought to an end by the want of projectiles for the land forces, while the ships of the navy possessed a surplus of the very articles required, which could not be used by the land forces. Not a single advantage is claimed for this lack of uniformity, while the disadvantages are very numerous and apparent. It has grown out of the fact that officers in the two branches of the service have succeeded in securing the adoption of their own inventions, and the rivalry existing between them has pre- vented fair competitive trials of the various devices and systems advo- cated by each, neither being willing to admit the merit of the other's inventions, or to utilize the knowledge gained either by their successes or failures. The experiments, being duplicated on account of this jeal- ousy, have been, necessarily, needlessly expensive. A further increased expense results, in time of war, from maintaining two separate organiza- tions for the procurement of arms. The two ordnance departments are brought into competition with each other in the matter of contracts and purchases of war material from the private workshops and factories of the country, thus putting the government in the attitude of bidding against itself. The investigations of the committee lead them to the following con- clusions : 1. That no more heavy guns should be purchased for mounting in the fortifications or use on shipboard until such improvements are made in methods of fabrication as will insure more reliable endurance than has heretofore been exhibited. 2. That the Rodman system of gun-making, while partially successful in smooth-bores and small calibres, has so far failed in rifles of large cali bre as to show it to be unworthy of further confidence. Recent improve- ments in defensive works and armor-plating render heavy rifled guns the most efficient means of attack, and no system of fabrication which does not furnish such guns should be adopted or continued. The principle of initial tension, which is the basis of the Rodman system, appears to be of doubtful utility, as applied by General Rodman, especially for rifled guns. This tension, it is admitted, gradually disappears from the gun with age, and in time is entirely lost. 3. That guns cast solid, in the manner practiced in the navy under the direction of Rear- Admiral Dahlgren, while exhibiting satisfactory endurance as smooth-bores with small charges and hollow projectiles, have not the requisite strength for rifles of large calibre. This mode of casting seems to be defective in principle, as the tensions inaugurated in cooling have a tendency to aid the powder to rupture the gun. 4. That experiments should be at once conducted for the purpose of ascertaining the real cause of the bursting of heavy guns, and of deter- mining upon some method of fabrication that will secure uniform endu- rance. 5. That every encouragement should be given to inventors, and a full and fair trial accorded to all devices offered to the government that promise a solution of the ordnance problem. 6. That more efficient means for harbor defence should be adopted. 6 EXPERIMENTS ON HEAVY ORDNANCE. The late war demonstrated that sand was the best material for defensive works, and that forts of masonry, such as we have now mainly to rely upon for the protection of our seaboard cities, are inefficient to prevent the passage of armored, or even wooden, vessels. The destruction of such defences is only a question of time to ordinary guns of heavy calibre. It was also demonstrated that forts alone, of whatever character, can- not resist the entrance to harbors of powerfully armed ships if the pre- ponderance of guns on the assailing fleet is sufficient. In the opinion of the committee, obstructions must be largely relied upon for harbor defence, in connection with properly constructed fortifications. 7. That no officer of the army or navy should be allowed to receive a patent for any article required, or likely to be required, for use in those branches of the public service, or to be in any way interested in the manufacture or procurement of such articles. It should be the duty of Congress to recognize by suitable rewards the services of such officers as might make inventions of especial value to the government. 8. That the ordnance department of the army can be entirely abolished with great advantage as to economy, and without detriment to the good of the service. The duties now performed by officers of that corps could be performed by officers detailed from the artillery service, under the direction of a chief stationed at Washington. In this manner the whole expense of the ordnance establishment would be saved, and artillery officers, who have not only scientific training but practical experience, would have a voice in the selection of the guns and ammunition they are required to use. The committee are of the opinion that for the reasons shown the inter- ests of the public service demand a change in the system of procuring ordnance and ordnance stores, and the manner of conducting experiments with a view to determining the value of the same. The present system has failed to answer the purpose for which it was designed, and the TJnited States is in the position to-day of a nation having a vast coast- line to defend, and a large navy, without a single rifled gun of large calibre, and a corps of ordnance officers who have thus far failed to dis- cover a remedy for the failure of the guns, or to master the rudiments of the science in which they have been trained at the public expense. The importance of an immediate change is shown by the fact that the Chief of Ordnance of the army asks for appropriations to purchase over 1,900 guns to arm the forts, not of a new and better system, to be decided upon after more thorough and careful experiment, but of a kind that experience has shown to be inferior in range and penetration to the guns of foreign powers, and unreliable as to endurance. It is proposed that 85 of these guns shall be smooth-bores of 20-inch calibre, 490 of 15-inch calibre, and 600 of 13-inch calibre. The experience of all nations goes to prove that the most effective way of developing ordnance power is by rifled guns. To return to smooth-bores, throwing huge spherical masses of iron with low velocities, is to disregard all modern progress in the science of gunnery, and to go back to the arm sin use two centuries ago. Furthermore, the advisability of using guns of such great size is very doubtful, for the slowness with which they can be handled and fired makes them less effective than smaller guns delivering a more rapid fire. Two hundred of the guns required it is proposed shall be Eodman 12-inch rifles, notwithstanding all of that class of guns here- tofore procured for the army or navy and subjected to test have either burst disastrously before the lowest reasonable test has been completed, or have given such indications of failing, after a few rounds, as to be considered unsafe. It is proposed also to purchase 610 10-inch Eodman EXPERIMENTS ON HEAVY ORDNANCE. 7 rifles, although the committee cannot learn that any gun of this class has ever been subjected to test in this country, except the Parrott rifles of that calibre, which are acknowledged failures, having been condemned by botji branches of the service. No progress towards obtaining better guns is likely to be made while the ordnance bureaus are organized as at present ; and the committee deem the best way to secure such impartially conducted experiments as will determine with certainty what are the best arms, and to insure greater economy and regard for the public interests in their purchase and adoption^ is in the formation of a mixed ordnance commission composed of officers of high character detailed from both the army and navy, who shall have no interest in patents on devices for arms. The committee report the accompanying bill, based upon the conclusions before set forth herein, and recommend its passage. APPENDIX A. Testimony. WASHINGTON, D. C., November 7, 1867. HORATIO AMES sworn and examined. By the CHAIRMAN pro tern. : 1. Question. What is your residence and occupation, and have you had any experience in the manufacture of heavy guns or ordnance ? Answer. I reside in Salisbury, Connecticut, and my occupation is, and has been for the last 30 years, in the manufacture of wrought iron. 2. Q. Will you state whether you have had any contract with the Kavy Department for the manufacture of ordnance j and if so, when and of what calibre and description such guns were to be ; and, generally, what were the terms of the contract, stating also whether you have delivered the guns or they have been accepted from you ; and if not, why they have not been so delivered or accepted, and where they are now ; and give a general history of the whole transaction ? A. In the summer of 1861 1 conceived the idea of making a wrought- iron rifled cannon, and applied to the Navy Department for a contract, and received an order to make five 50-pounders. These guns were made at great loss to me, it being an experiment. One of the guns was fired 1,630 times without essential injury. Another of the lot was made into an 80-pounder by enlarging the bore from five and one-tenth inches to six inches, and fired 480 times without damage. Six of these guns were received and paid for. In the fall of 1803 President Lincoln gave me an order for 15 rifled guns of the largest calibre I would undertake to make, leaving the size, shape, and calibre to me. These guns were com- pleted in about a year and a half. One of them was fired 700 times with more and heavier charges than any gun has been knoAvn to stand, as the report of General Gillmore, Colonel T. T. S. Laidley, and Commo- dore Hunt will show. Two of these 15 guns came apart in proof. These guns weighed over 19,01)0 pounds each, and our machinery, tools, &c., were not large enough to manage the work successfully. In the winter of 1865 I received another contract from the Navy Department, or an order, to make 11 guns, corresponding to the one proved at Bridgeport. These gnus were made, and in August, 1865, one was ready for proof. The government reserved to itself the manner of rifling the guns.' Two of these guns were rifled in different methods, by order of the depart- ment, of untried or experimental kinds ; and although the guns were never tried, to know if the rifling was good or bad, they were abandoned and new rifling was put into two more guns of 60-feet twist, which insured their destruction, as there was not twist enough in them to give the shot the proper rotary motion. Four of these guns were merely fired to burst or otherwise destroy them. Each was merely fired into a bank of earth without reference to precision, range, or velocity. The fifteenth gun, at my request, was fired for range, at Bridgeport, and it was judged that the twist was too slow to do good work. Besides, the powder which was ordered, and believed to be 1,450 feet velocity, gave. 10 EXPERIMENTS ON HEAVY ORDNANCE. when proved, but 1,100 to 1,200 feet. In fact, nothing of their quality has been established except that they cannot be burst. The complaint that the bore has been enlarged by tiring, which is not a very serious one, can be remedied by firing the gun with heavy charges when one- tenth inch below size, and will so compress the metal that it may be fired a thousand times with heavy charges, and not materially further enlarge. The cracks spoken of in the report are mere fissures, which are not dangerous, and have not so proved. All wrought iron is liable to show slight fissures, which do not impair its value, None have burst in consequence of these fissures, and they can scarcely be called imper- fections. In comparison with wrought-iron guns made in this country and in Europe, they would be considered perfect. At any rate, they have stood double the ammunition at the charge any gun we have has endured. Were you to examine these guns now you would have no hes- itation in pronouncing them good in all respects conforming to the con- tract. The contract for these guns states explicitly that the normal charge for them shall be 10 pounds or 12 pounds. Yet none of them have been fired with these charges to show their endurance. It is known that the istrain upon a rifled gun is twice and a half that upon a smooth- bore gun, and that 40,000 pounds pressure upon the square inch of the bore is the standard strain of common powder. Yet my gun has had used in it powder more than twice as strong, which I believe has four times the tendency to burst the gun. English powder gives even less than 40,000 pounds to the inch. These 100-pounder guns have been made of the kind of material called for by the contract, and are better guns than the one which the contract specifies they shall be like. A commission was .called to examine these guns, on the question whether these " were suitable and proper guns to be put on board ship." They decided they were not, because they had been fired with excessive charges, greater than they would ever be called upon to bear. The department had already decided the question, "that no gun should be put on board ship that had been fired to excessive proof." This commis- sion also recommended that they be further fired with the charges named in the contract ; but no notice was ever taken of this recommendation. I asked the bureau to make a comparative test with any gun made or to be made ; but it was refused. With the charges used in my gun almost every shot broke in the firing ; and there are tons of shot broken in the guns and out of them, weighing from one to ten and twenty pounds. And I venture to say that the guns rejected by the department will stand with equal charges rounds enough to burst 100 guns of any other make the government possessed of equal calibre. These guns now lie in my works, six of them finished, and five of them wanting the rifling put into them to complete them. None of them have been accepted. I refer you to the evidence given before the Committee on the Conduct of the War, in 1864-'65, and the testimony given by Commodore Hitchcock and Commodore T. A. Hunt, on the proof of these guns. No metal can stand the strain and shock of powder in excessive quantity without injury; and my meaning of the contract was that the ordinary powder used (if 20 pounds to the charge) would not burst the guns, and it has not. And I do not believe there has ever been a gun that has stood so much. I am informed and believe that a wrought-iron gun, made by direction of the Navy Department, by Captain Ericsson, at a cost of from $30,000 to $40,000, though it failed completely after 30 rounds, was paid for in full ; also an 80-pounder wrought-iron gun made at Heading, Pennsylvania, though never fired, and worthless, was paid for by the department. A wrought-iron 80-pounder was made at the navy yard. EXPERIMENTS ON HEAVY ORDNANCE. 11 at a great cost, never has been fired, and snows unmistakable evidence of its unfitness for service. I have at times called upon the department to continue the firing of these guns with suitable powder and shot, but my request has not been complied with ; and I am refused payment for my guns under the frivolous pretext that they do not answer the terms of the contract. Had these guns been properly rifled and proved with their normal charges, as specified in the contract, no complaint could have been made of their quality. Nor do they now show, after the unparalleled proof they have withstood, any serious fault. WASHINGTON, November 11, 1867. THOMAS TAYLOR sworn and examined. By Mr. LOGAN: 1. Question. I understand from your former testimony that you have had considerable experience in experimental firing of guns at Fortress Monroe! Answer. Yes, sir. 2. Q. Have you any knowledge of the bursting of any Kodrnan guns at that place I A. Yes, sir. 3. Q. Of what calibre were they ! A. Two 8-inch burst and one 12-inch. 4. Q. How many rounds had the 8-inch guns been fired respectively? A. One of 1,500 rounds and the other 50. The 12-inch about 35. 5. Q. Were uniform intervals allowed to elapse between each round I A. No, sir; we fired them as fast as we could load and fire and prepare instruments to take velocities. 6. Q. About how great a length of time on the average elapsed between each round ? A. Perhaps ten minutes ; sometimes it might be half an hour. 7. Q. Sometimes longer ? A. Yes, sir; that arises from the machine sometimes not working well. 8. Q. After each round you applied certain instruments and made a certain examination of the gun I A. No, sir; we have two instruments for taking the initial velocities; one is Schultz's chroinoscope and the other Benton's ballistic pendulum. With these we take the velocities. They sometimes get out of order. 9. Q. What was the weight of powder used in the 8-inch and 12-inch guns respectively. A. Fifteen pounds of rebel powder ; which gives a velocity of about 1,250 feet per second. 10. Q. Do you mean to say rebel powder is better than ours f A. We had some powder called rebel (which I suspect was English) which was very good. 11. Q. I understand you to say a 12-inch gun burst after how many rounds ? A. One 12-inch burst after 35 rounds. That is known as the Atwater navy gun. It is a Rodman gun rifled on the Atwater principle. 12. Q. How long a time was consumed in firing those 35 rounds I A. A good many months maybe six. 13. Q. Are you aware of any other 12-inch guns that have been made for the army and navy ? A. I understand there are two others made for the navy. 12 EXPERIMENTS ON HEAVY ORDNANCE. 14. Q. Do you know of any other instances where they have burst? A. These burst. There were but three of them made and they burst. 15. Q. How many rounds were these others fired that burst? A. I believe they all burst under 50 rounds. 16. Q. What kind of projectiles were fired in them? A. The projectiles, I believe, were mixed. Parrott projectiles, I think, were mostly used, but I am not very sure. With regard to the two that were burst by the Navy Department, I have only second-hand informa- tion. The one that burst at Fortress Monroe was served mostly with the Dyer projectile. 17. Q. Will you explain in what the Atwater system of rifling consists? What its peculiarity ? A. It consists in removing one-half the lands out of the gun from the muzzle towards the breach one-half in number and one-half in length. 18. Q. And the Dyer projectile extends into the grooves ? A. Yes, sir. 19. Q. In those that were recovered was it found that the soft metal band had expanded, enlarged in the grooves towards the muzzle? A. No, sir. 20. Q. What kind of powder did you use ? A. Generally, I believe, mammoth powder. 21. Q. The object of using mammoth powder as I am informed is to continue the pressure of the gases against the shot farther towards the muzzle ? A. Yes, sir. 22. Q. And yet the pressure was not sufficient to expand the lead into the grooves when the shot had moved half the length of the gun ? A. No, sir; in no case. 23. Q. What has been the proof of heavy guns, as far as you know, at Fortress Monroe that is, what has been considered the proof of the guns ? A. We were firing about 15 pounds, which was the standard charge for 8-inch guns. 24. Q. How many rounds firing ? A. Do you mean at a time ? 25. Q. No, I mean the entire proof. A. We did not prove in that way. Parrott would fire ten rounds and be done with it, whereas we would fire a thousand if it would stand it. 26. Q. Has a 12 or 15-inch gun ever to your knowledge been fired 20 or 30 rounds in course of proof in as rapid succession as it could be loaded and fired ? A. Do you mean rifled ? 27. Q. Yes, I mean rifled. A. A rifled 12-inch gun has been fired in my presence 10 times with double charges in 35J minutes. 28. Q. Has it ever been fired 20 or 30 times in as rapid succession ? A. No, sir. 29. Q. Has the 15-inch Eodman gun, to your 'knowledge, ever been fired that number of times in rapid succession ? A. It has been fired 10 times with hundred-pound charges in my presence, and I think that is the most rapid that it has been fired. 30. Q. Do you know any reason why the firing was not continued beyond the 10 rounds as a further test? A. I asked the colonel if it would not be well to fire it 20 rounds and get over the assertion of Mr. Wiard that it could not ; and he did not give me any answer. EXPEEIMENTS ON HEAVY ORDNANCE. 13 WASHINGTON, November 11, 1867. TIMOTHY A. HUNT, commodore United States navy, sworn and ex- amined. By the OH AIRMAN pro tern. : 1. Q. How have you been em ployed for the most part during the war? A. In the fore part of the war I was in the Pacific ocean. Was ordered home in 1862, placed on ordnance duty, and have been on that duty since. 2. Q. Were you a member of the commission to try the Ames gun at Bridgeport in 1864 and in 1866? A. Yes, sir. 3. Q. How many did you try in 1864 and how many in 1866 ? A. At Bridgeport we tried one in 1866 for range only, and tried two of the same class at Falls Village in the same year. 4. Q. Will you state what was the result of those trials ? A. The first gun fired in 1864 was a 7-inch bore. It was fired 700 rounds with different charges of powder from 19 pounds up to 30 pounds. It stood the test very well. 5. Q. In making a trial of guns do you use a charge large enough to give the greatest velocity to the shot ? A. No, sir; in proving cast-iron guns we use the service charge only, which does not give the greatest velocity 10 rounds of the service charge. The first gun is fired a thousand rounds service charge, and all after that is made as near like the trial gun as possible, and fired with 10 rounds. 6. Q. When you fixed the Ames wrought-iron gun, did you use the service charge ? A. No, sir ; I do not know that any service charge had been determined upon for this gun. We used 15 pounds, 25 pounds, and up to 30 pounds of powder. Then we were trying the strength of the gun. 7. Q. Did you make any calculation to ascertain what should properly be the service charge for a gun of that description and confine your- selves to that ? A. No, sir. 8. Q. Why did you use these different charges I A. To see what the gun would stand and how far it would throw shot. 9.. Q. Were those sized charges selected by the commission themselves or were they used under instructions from the Ordnance Bureau?- A. The first was selected by the commission ; General Gillrnore was at the head of that. 10. Q. Did you use the same sort of charges when the first gun was tried I A. That was the one I have reference to, in which we used charges of 25 pounds and 30 pounds. 11. Q. How was it in 1866 I A. That gun was fired merely for the range. 12. Q. With large charges such as you used in the Ames gun, how many rounds could you fire in a cast-iron gun without destroying it ? A. I do not know, sir ; it would not stand so many, I think, as the Ames gun. 13. Q. Would it stand such charges at all ? A. It might stand a few. 14. Q. Did you make reports on this subject to the Ordnance Bureau from Falls Village, Connecticut, on the 22d day of February, 1866, and 14 EXPERIMENTS ON HEAVY ORDNANCE. from the same place on the 10th of March, 1866, and on the 14th of March, 1866, and on the 24th and 27th of March, the 10th of April, and on the 14th of September, 1866 ! A. Yes, sir ; those are all my reports. 15. Q. Besides these official reports made by you, have you written any unofficial communications to the chief of that bureau upon the sub- ject of these guns f A. Yes, sir ; I made some, but of the same tenor as the official reports ; and those private reports I find are also on file. 16. Q. Do you remember to have said anything about the quality of these guns more fully in your private communications than in the official report I A. No, sir ; I do not know that I did. 17. Q. What was the kind of powder used in your proof of these guns? A. I think the powder we used at Bridgeport was No. 7 Hazard's powder, with initial velocity 1,440 or 1,450 feet. 18. Q. Was it a quick-burning, fulminate powder, more likely to burst a gun than that ordinarily used in the service charge ? A. No, sir j I think not. It was such powder as we put on ship-board. It was sent from New York magazine, from the same lot out of which we got powder to put on ship -board for service. 19. Q. Did the shot break in the gun or outside of it in these trials ? A. Not in the trial at Bridgeport. I fired two guns afterwards at Falls Village. We fired it 220 rounds with 20 pounds each charge, and shot weighing 100 pounds, and five, I think, of 10-pound charges, and 10 of 15 pounds ; making 235 charges. 20. Q. With what result? A. The gun was very much enlarged in the bore in the rear of the shot. Eight in the centre of the bottom of the bore there was a depres- sion commenced after firing 15 or 20 rounds ; and that depression kept eating in to the depth of four inches. 21. Q. How large was that orifice in circumference I A. Large enough to insert the little finger. 22. Q. To what did you attribute that ? A. The pressure of the powder ; and owing to the sulphur in the pow- der, when any abrasion takes place in cast-iron, and the powder once gets hold of it, it eats in very fast. 23. Q. Then it is not to be accounted for entirely by the pressure, but by the corrosive character of the gases. A. The pressure in the first place dents it in, but when the corrosive quality of the gas once gets hold of wrought iron it eats in very fast. There were some other defects in the chamber of that gun, but the bore was in very good condition, according to the charge of powder. 24. Q. What was your general conclusion in your report and the con- clusion you arrived at in your mind as to the value of these guns. A. The wrought-iron guns I consider the strongest guns that can be made ; stronger than any we have, provided the welds are secure. There is no doubt that gun at Bridgeport stood remarkably well longer than any cast-iron gun we have in the service. I think the last two guns that I fired also stood charges of powder that cast-iron guns would not stand. 25. Q. How would it have been in active service if these guns had been used with a proper service charge j do you consider they would have been effective guns I A. I do not think they would have enlarged or that these depressions EXPERIMENTS ON HEAVY ORDNANCE. 15 would have occurred, if they had been fired with less charges. I think this 6 T 4 Q~inch gun will not stand successive charges of 20 pounds of pow- der and 100-pound shot. 26. Q. Is it your opinion, then, that if these guns of Mr. Ames had been used in active service with a proportionate service charge of pow- der only, they would have proved effective and useful guns I A. It is very probable, sir. 27. Q. Is it the practice, or has it been for many years, of the Navy Department to test guns with more than the service charge ? A. No, sir; I have proved a great many guns, and have always proved them with the service charge. After the guns are offered for proof we fire them with 10 rounds service charge. 28. Q. The reason then for increasing the charge in the trial of these guns was because it was a gun of new manufacture I A. Yes, sir ; something new ; some doubt as to the weld of the gun. 29. Q. And it was not the ordinary trial of a navy gun ! A. No, sir ; something new. 30. Q. Did you answer in regard to the breaking of shot f A. No shot were broken in the gun j but the bands would fly off after leaving the gun, but the most of them broke on striking the bank into which they were fired. 31. Q. Were those shells with soft metal bands at the base of the shell ! A. Yes, sir; composition. 32. Q. Have you ever known what, in your opinion, was a better or stronger gun in our service than this Ames gun, as you would judge from that trial of them f A. I have never known any gun to stand the test that 7-inch gun stood, and also the one that was fired at Falls Tillage. The second gun fired at Bridgeport was fired only 45 times ; that was not much of a test, it was merely fired so as to get the range. 33. Q. I asked if you know of any better or stronger gun in our service. A. I say the first gun was the strongest and stood the best test of any gun I have known in our service ; but I cannot say as to the last, for that was only fired 45 times, and simply to secure the range. 34. Q. Suppose you were in a fight with an enemy, would you or not like to trust to these guns such as you tried there ? A. It is a new gun, and there is some doubt, as I said before, about the welding. If the gun is perfectly welded there is no stronger gun made. But we have to run some risk with all guns, cast iron as well as wrought iron, and the wrought iron being a new gun there is some doubt about it. There is no doubt the wrought-iron gun would stand remark- ably well with a charge of 10 pounds or 12 pounds of powder. 35. Q. If you can get a good gun that will give a greater velocity to the shot than any other having more strength to stand the charge, is not that gun proportionately more valuable for war purposes f A. Certainly, sir. 36. Q. Will any cast-iron rifled gun in your opinion stand the shock of a charge that would give 1,500 feet velocity per second ? A. It might for some few charges, but I think not for any consecutive number of charges. Is not a wrought-iron gun of this kind strong enough to give that or a greater velocity if you can depend on the safety of the gun ? Yes, sir; I think that these guns cannot be bursted expansively. If they burst anywhere it would be the weld fly off in the rear. Did any Ames guns out of those you proved burst f 16 EXPERIMENTS ON HEAVY ORDNANCE. No, Sir. What defects did you observe developed in the trial of the gun besides this orifice or cavity that was produced at the bottom of the bore ? There were some few around in the circle of the bore. A crack or cavity went nearly round the gun, and that kept eating in as we fired. Was it at a line where the weldiDg took place I I should think not ; it was in the chamber of the gun, that is in the bottom of the bore. What was your conclusion in regard to the principle upon which Mr. Ames has been manufacturing these wrought-iron guns ? I think his principle is the best we know of at the present day ; think it will make the best gun. I think it is a much safer way than welding them in coils as the Armstrong and other guns are made . 37. Q. Do you know how that process is accomplished by Mr. Ames ? A. Yes, sir; there are three rings concentric rings. The lower one projects a little and the next one a little more : so that when the two parts are brought together to be welded, these rings are about six inches in depth, and as they are brought together the middle takes first as the welding goes on, and the outside ring takes last, with the object of let- ting off the scoriae produced by the oxidation of the iron, so as to have a clean weld ; and if you can keep clear of all these cinders and the ex- coriation which takes place as soon as the iron is brought to the atmos- phere, you can make a perfect weld of it. 38. Q. Was your attention directed to the rifling of these guns ? A. The rifling of the guns was a regular twist one turn to 60 feet. That was the rifling of the gun which I fired for Mr. Ames at Bridgeport, in 1865, which in my opinion was no test for any other gun. I do not think there is any comparison to be made with that and any other gun. For that reason I fired it but 45 rounds. 39. Q. That twist was selected and ordered by the Ordnance Bureau? A. Yes, sir. 40. Q. Do you know whether Mr. Ames himself objected to that rifling? A. I do not know, sir. When I saw the result I thought it bad rifling to give long range that there was not rotary motion enough for the shot. Before the force of the shot was expended, the rotary motion was done and of course the shot would not go as far. 41. Q. What rifling would you prefer for a gun of large calibre like that one which would commence with a slow turn and quicken as it- approached the muzzle, or would you have uniform rifling ? A. There is a difference of opinion about that. 42. Q. I know there is, and that is the reason why I ask you the ques- tion. A. We know very little about the rifling of guns. My idea is that we should get a number of guns of the same calibre, and rifle them all dif- ferently, and fire them with the same powder and at the same time, and see which gives the greatest range and velocity ; and that until that is done we shall reach no satisfactory conclusion. 43. Q. Do you know whether there ever has been such an experiment or series of experiments in order to test the value of differently propor- tioned rifling of guns, by either the army or navy ? A. There were some experiments made by the navy of Parrott's rifling, At water's rifling, and, I think, Rodman's or some other, and it was con- sidered that Atwater's rifling was the best, gave the best results. 44. Q. What is the peculiarity of that rifling J ? A. It is that after the shot gets started he cuts away the grooves so that there is not so much friction half way down the gun. The lands EXPERIMENTS ON HEAVY ORDNANCE. 17 were cut half way out and made smaller so as to prevent so much fric- tion and cause the rotary motion. 45. Q. Do you know whether any experiments have been tried with guns precisely similar in calibre, length and construction in every re- spect except the diiference of the twist in rifling, and the difference in result between an uniform rifling and a rifling commencing slowly and increasing ? A. No, sir $ I do not know the experiment of that kind that has been made. They may theorize as much as they please about gunpowder, they never can come to any conclusion except by practical tests. 46. Q. Do you believe the velocity of shot and the range of guns can be calculated with mathematical accuracy, when you have the calibre, the weight of the shot, the charge of powder and the shape of the shot all given ? Or do you think it is necessary to add experience to these conclusions ? A. There must be experience added to them. If everything could be made exactly alike, they might do it, but there are so many variations in the i>owder, shot, guns, and conditions, that it cannot be carried out to a mathematical point. WASHINGTON, November 11, 1867. E. B. HITCHCOCK sworn and examined. By the CHAIRMAN pro tern : 1. Question. Will you state in what service you are, and your rank'? Answer. I am commodore in the United States navy. 2. Q. What is the ordinary proof to which smooth-bore or rifled guns in the naval service are subjected? A. In making a contract or engagement for any special class of guns they take the first of that class and submit it to what is ternied extra- ordinary proof, that is, a thousand rounds of service charge. The others are supposed to be duplicates of that gun. They are submitted to 10 charges of service rounds. 3. Q. You take one gun of a class ? A. Yes. For instance, if you were going to make 9-inch guns you would take the first and submit that to the extraordinary proof of 1,000 rounds. 4. Q. The extreme proof is 1,000 rounds f A. That is the initiatory proof of a class of guns. The others are supposed to be duplicates, and before reception in the service they are fired 10 rounds. 5. Q. What is the extreme proof to which you subject such guns in the navy, as it regards the charge of powder and its kind! A. We have no proof for powder or shot in the ordnance for proving guns. The proof of powder is a thing by itself. 6. Q. But what is the extreme proof as it regards the size of the charge? A. That depends on whether it is a smooth-bore or rifled gun. 7. Q. What is the extreme proof to which you subject a smooth-bore gun, as it regards the size of the charge and shot used? A. We use the service charge all the way through for any kind of proof 5 and our service charges for smooth-bore guns have varied, gene- erally to one-fourth and one-eighth, with permission to use one-third in service on some occasions. During this last war there were special pro- visions made for going far beyond that. It was restricted at the com- mencement of the war particularly to certain charges. Daring the war experiments indicated that it might be increased with safety, and per- mission was given to increase. Eep. No. 266 2 18 EXPERIMENTS ON HEAVY ORDNANCE. 8. Q. How is it with regard to rifled guns? A. One-tenth is the service charge. 9. Q. Then your test iu the navy is one made rather by the number of discharges? A. The durability of the gun. ^Looking to the life of the gun," as we sometimes call it in service. 10. Q. What is considered the measure of the life of a gun in the naval service. A. About 800 discharges. Not but what it will stand more than that, but we look for about 800. The Ordnance Office has withdrawn them at 500. But we think when a gun has been fired 800 rounds it ought to be withdrawn. 11. Q. Your rule is generally that you test guns by the number of rounds you fire. A. Yes, sir. 12. Q. You fire a number of rounds with the service charge? A. Yes, sir. 13. Q. And if the first gun of a class stands a thousand rounds you are ready to accept the others always upon the ordinary test of 10 rounds'? A. Yes ; ten rounds always ; those numbers are fixed. 14. Q. What is the lowest tensile strength of iron permitted to be used for guns in the navy, and does it differ in those of different cali- bres? A. The tensile strength is a thing that was at one time insisted upon with great uniformity and great confidence. We thought we might rely upon it. Afterwards we became doubtful whether it Avas an indication of that importance we had supposed it to be, and of late it has not been insisted upon ; so that I can hardly say. It has been named, you will find in reports, when a contract has been made, that there has been a certain tensile strength; and afterwards orders have been given where it has not been insisted upon from doubts arising in relation to its being so reliable an indicator as it was once supposed to be. When Major Wade made his experiments, followed up by Mr. Mordecai, we supposed we had an infallible guide. I think now they have more confidence in it in the army than we have in the navy. We tried the tensile strength of iron at all the navy yards. We have specimens of the guns, but we do not think it so infallible a test as we formerly did. 15. Q. Do you recollect what was the rule ordinarily observed in the navy in relation to iron, as to the highest and lowest degrees of tensile strength ? what were the two extremes ? A. I do not recollect, sir; but it is a matter of record in any of the text- books, either army or navy. 16. Q. Did you approve two of these wrought-iron rifled guns that were constructed by Mr. Horatio Ames I A. We fired them under orders, but not with a view of experiment at all. Definite orders were given me, which I carried out. I had no voli- tion in changing anything at all. It was not an experiment that I was sent there to use judgment upon, but simply to carry out orders. My duties were prescribed. 17. Q. Instead of your being detailed, then, to experiment and report your judgment of the guns, you were detailed to perform a specific duty ? A. Yes, sir ; and to report the result as facts. 18. Q. How many charges did you fire, and what was the weight of powder and shot ? A. I will have to ask your indulgence to refer to the written report. There is .a written report of all these details. In .the last twenty years EXPERIMENTS ON HEAVY ORDNANCE. 19 sir, these things are so much mixed up in my mind that I may uninten- tionally make a wrong statement. 19. Q.. In the reports that you made to the Ordnance Bureau of the Navy Department, on the 12th day of August, 1865, and on the 4th day of September of the same year, from the West Point foundry, in relation to your trial of the Ames guns, did you confine yourself to just that trial which you had been ordered to make without exercising any discretion of your own ? A. Strictly so ; the orders were definite and strictly complied with. 20. Q. Will you tell me whether that is the usual number and amount of charges used in proving guns of that calibre. A. I should say no, sir ; so far as my experience goes. The bureau gives orders for a trial. If they do not prescribe differently it would be 10 ordinary service charges. They did not assign to this gun what the service charge should be. If it had been a gun that had been in the service, it would have had its charges assigned. We would simply have been ordered to prove this gun and to use these charges. 21. Q. If you had been directed at your discretion to make that trial, would you not in the first place have made the trial with the ordinary service charge ? A. In former times, when we proved guns, we used excessive charges some two or three rounds, but very excessive. We put in a number of projectiles in the guns smooth-bore guns. When I was first detailed for ordnance duty, that was the practice. I was very much opposed to it, although it is twenty years ago ; and in long conversations with Com- modore Warrington, then chief of the bureau, I think I influenced him to change the order and use the service charges. If I were going to have service charges of two or three different weights of powder, I would always commence with a new gun on the lowest charges. 22. Q. If the trial had been left to your discretion, you would have gone on testing with charges, and endeavoring, in a new gun, different from any former one, to ascertain what would have been the proper ser- vice charge to be settled for that gun ? A. We would ascertain what would be the proper charge. 23. Q. You would have calculated what would be the proper service charge for that gun and have made your trial from that f A. Yes, certainly ; and if practical experience confirmed the theory, we would have held to it. 24. Q. The trial made with this gun was made with excessive charges rather with a view to see whether you could burst the gun, to ascertain what its duration would be ? A. No,, sir; that was not my impression. They commenced by using 10 pounds charge and increased it to 15- pounds and 20 pounds to see what the effect would be, not to rupture the gun ; to see what the effect would be on wrought iron cooled in the manner that was. I suppose they wanted so see what the effect of 10 pounds would be, and then in increasing it to see if it produced any other effect on the wrought iron. 25. Q. Beside your report made after the trial in each case, did you write any unofficial letters to the bureau advising them on the subject? A. I cannot say whether I did or did not, sir. We were in the habit of writing unofficial letters to the bureau. I have written a great many unofficial notes, but we were very much pressed at that time in relation to our work, and I should be disposed to say I did not. But I cannot say I did or did not. I have no recollection of doing it. 26. Q. Do you know of any shot that were broken in or out of the gun in this firing ? 20 EXPERIMENTS ON HEAVY ORDNANCE. A. I do fiot remember any of them being broken there. I would rather rely upon the report in regard to that. I do not think any of them were broken there, sir. 27. Q. Did you use the same powder in firing these guns you did in firing the Parrott guns ? A. With one exception I have never used any but service powder. The powder for these guns was ordered from New York, just as any pow- der for proof is ordered. It was not a selection of powder. 28. Q. In these trials of the Ames guns at West Point foundry, you used the same powder as you used in other trials f A. Yes, sir ; used the ordinary service powder. 29. Q. It was not, then, a quick-burning, fulminate powder? t A. It was either to be cannon or No. 7 powder, and the initial velocity was to be 1,500 feet for one and so much for the other. Those standards are laid down in the ordnance instructions. 30. Q. Did you use what is called the water-proof of guns there some- times*'? and if so describe how you apply the water. A. It is a hydraulic pump of very small construction capable of rais- ing a weight of two atmospheres, merely pressure enough to force the water into any cavity that may exist. It produces no strain. 31. Q. Did you put either of these guns through that water-proof? A. Yes, sir ; I did. 32. Q. With what effect? A. There is no effect produced by that unless there is some little cavity which will retain the moisture longer than other parts. 33. Q. If a gun is remarkably porous $he water sometimes conies through? A. -I have seen it come through wrought-iron guns. 34. Q. Would the degree of pressure to which you submitted one or both of these guns in that water-proof have burst a cast-iron gun ? A. No $ it is only two atmosphere. It is not used with that idea. The object is simply to find whether there are any little cavities. I never have used this pressure of two atmospheres with an idea I was going to develop anything further than letting the water get into some porous place. We are not at liberty to increase the hydraulic pressure. We are confined to two atmospheres. 35. Q. Did you ever fire any charges in a Parrott gun of the same calibre as large as the largest you fired in this Ames gun ? A. Yes, sir ; but I was confined to certain instructions. I have tried experiments with Parrottfs guns, but not under orders from the ordnance bureau. They were experiments being tried with guns where the navy had nothing to do with it. 36. What was the effect of the 20 pounds charge on the Parrott gun? A. There was no injury to the gun in that instance. 37. Q. What is the service charge now in a Parrott 100-pounder ? A. Ten pounds. 38. Q. Is that regarded as charge enough to give the highest velocity to the shot? A. They settled on the ten pounds as a mean, as being the best in the long run both for wear of the gun and for safety and for many other con- siderations. Certainly a higher velocity might be obtained with more powder. 39. Q. Would you consider that gun a good gun that would not stand charge enough to give the highest velocity to the shot ? A. Yes, sir ; but I would consider the gun that would give the greatest velocity the better gun. EXPERIMENTS ON HEAVY ORDNANCE. 21 40. Q. Would you considerthat a good gun that would not stand charge enough to give the highest velocity ? A. Yes, sir ; I would consider such a gun a good serviceable gun, yet not the best ; because the best would be one that would combine all the advantages. 41. Q. Do you know the Dahlgreii shell gun ? A. I know it, but not enough to give answers in relation to it. 42. Q. Do you know whether that gun will stand a heavy enough charge of powder to give the highest velocity to the shot? A. Some of them would not. I think there is a great difference in those guns. I think the 50-pounder was a very good gun, and all the large ones perfectly worthless, because they would not stand. 43. Q. Do you know any gun that will stand any considerable number of rounds, yet giving the highest velocity to the shot ? A. I do not believe they exist anywhere, sir. 1 do not believe any such gun has yet been produced. Not any large number of rounds. I think there are guns that will afford the highest velocity powder can give for a few rounds. 44. Q. After the experience at Fort Fisher, was the service charge for the 100-pounder Parrott gun reduced? A. I am not quite positive about that; I wasoii board, too, in relation to that charge. I am rather under the impression it was, and I think I voted against .it. That is a matter of record. 45. Q. Is not the service charge of the Parrott gun now eight pounds ? A. I think it is reduced down to eight pounds. 46. Q. You have been inspecting these Parrott guns for years, have you not? A. Not for the last two or three years. I was employed a number of years inspecting them. I inspected the first guns the navy ever took and the last they took, and all between, with exception of one year's. 47. Q. What was the cause of some of the Parrott guns being bored out of centre ? A. From not duly watching the machine. It is somewhat difficult after a gun is bored to determine whether the bore is precisely in the centre, and the demand was so urgent that some were sent out without having been properly tested. 48. Q. You attribute the fact of any guns having gone out which, from defect of machinery, were not bored perfectly in the centre, to the haste of producing guns required at that time ? A. I think that was the reason. 49. Q. Can you throw a shot from a Parrott 100-pounder as far with 8 pounds or 10 pounds of powder as you could with 15 or 20 pounds f A. Certainly not, sir. 50. Q. Are you acquainted with the English wrought-iron steel gun particularly the Armstrong gun ? A. No, sir ; only from general Information. 51. Q. Do you know the quantity of powder used for the charge of the different calibres of those guns ? A. I have seen it stated, sir, from time to time. They have charged the amount of powder in those guns repeatedly. They have advanced and receded. The first guns put on their naval ships was at a very low rate. They then increased them, and again reduced them. I knew of the firing of the first Armstrong gun made in the United State made by Mr. Parrott made for the Russian government, sir. W^hen it was supposed to be a secret in England the Russian government obtained by some means the plan of the Armstrong gun and brought it to Parrott 22 EXPERIMENTS ON HEAVY ORDNANCE. and lie made one of the guns ; and strange to say, the best of ranges that have ever been obtained by Armstrong's guns were obtained by the one made by Parrott accidental, undoubtedly. 52. Q. Has there not been some understanding that an American inventor, even before Armstrong's time, produced a gun of that kind and exhibited it to the navy bureau? A. Do you mean Professor TreadwelPs gun ? 53. Q. I do now know whose it was. A. There is a gun a great deal like Armstrong's gun, but the name of the inventor has escaped me. I fired the gun for him here. 54. Q. How long ago was that ? A. That was 15 or 18 years ago. Chambers's gun, ihe first one he got up, was a good deal like the Armstrong gun. 55. Q. That was before the Armstrong invention came out? A. Yes, sir; before we knew anything about it. The guns did not look alike, but the principle was very much the same. 56. Q. For what purpose did you use an SO-pound shot in a 100-pounder gun? A. The shot was used for penetration, sir ; to determine its power of penetration. 57. Q. Will you explain the common twist of the rifling used in the Parrott gun ? A. It is an increasing twist begins slowly and increases in curve towards the muzzle. 58. Q. Do you think that is the best twist for a 100-pounder? A. It depends on the projectile that is used, how the projectile takes the twist. I think it is the best one with the projectile that is caused to take the groove by the band. 59. Q. What is the twist of tl^e Ames gun? A. Two twists one of Mr. Parrottfs and one of what we call Brooks's. 60. Q. One was a 60-foot twist? A. That was the Brooks. 61. Q. A very slow twist, was it not? A. Yes, sir. 62. Q. What do you think of that 60-foot twist? A. I do not like it, sir, for the projectiles we use. Do not think you get as great an effect. 63. Q. Do you get as long a range ? A. I do not think you do. I think, as I said before, thu ^arrott twist is the best adapted to the expansibility of the ring. 64. Q. Do they fire larger charges in the Armstrong or English wrought- iroii guns than in the rifled guns we have in this country ? A. Of my own knowledge the last of the Armstrong guns they had at sea was fired first with one-tenth ; they then came down to one- twelfth, having, in their experiments, gone to very high charges. 65. Q. Who is Brooks, and how came that rifling? A. He once belonged to our navy. I am sorry to say the last I heard of him he was fighting against us. Mr. Brooks is a man of a good deal* of cleverness. He got his first reputation from, a sounding apparatus when he belonged to the Coast Survey. I do not fancy his rifling. How- ever, that is a matter of mere opinion. He does. 66. Q. What are the velocity and range of a Parrott 100-pounder gun charged with eight pounds of powder ? A. That I cannot say, sir. They have, I think, about 1,200 feet with 10 pounds of powder. 67. Q. Since the reduction of the charge, do you know of any experi- ments to determine the range? EXPERIMENTS ON HEAVY ORDNANCE. 23 A. I never saw an 8-pound charge fired out of one of these guns, and I have seen thousands upon thousands of the others. 68. Q. You think that gun should and would stand 10 pounds! A. I ought to think so, sir, when I have seen 20,000 or 30,000 rounds fired with them. I simply base my opinion on that. 69. Q. What is your estimate of the difference in value between a gun that must be fired with eight pounds of powder and one that would stand firing with 15 or 20 pounds. A. It would be just in an inverse ratio to this amount. The gun that would stand the heaviest charge would be the most valuable. Run it down to the gun that would not stand powder enough to throw the ball out, and its value would be represented by a 0. 70. Q. Do you know of any gun that has yet been produced stronger than the experiment would lead you to think this Ames gun might be in use ? A. My ideas may be very peculiar. I was called upon to look at Mr. Ames's effort when he first commenced his first gun. I was delighted to see he had struck out on what I thought was dangerous business, to work wrought iron, and hoped every success might attend his effort, knowing perfectly well that was the siJfongest form iron could be presented in if true iron all the way through. The only difficulty in my mind was making it perfect. I doubted if he was able to make a gun with perfect certainty. He made a gun, and, as Colonel Laidley has just testified, and the report shows, it was fired at Bridgeport, and endured remark- ably ; but the question was, with the intention of making* the next gun identically the same, whether he would be successful, or could be assured it was the same. They tried another gun and found it was not. That was just my fear of the danger of working wrought iron. You might cut open ten guns in succession, every one being perfect, but I am not certain the eleventh would be. I am not a mechanic, but I have watched them at their work a great deal, and I find them very frequently making mistakes in heavy welds. The high heat certainly oxidizes iron very frequently. That oxide interposes itself between the true iron. I think I have seen that in one of Mr. Ames's guns. 71. Q. Your idea then is this, that in making cast-iron guns there may be such uniformity in the character of the material employed that you can safely trust to a class of guns when one of that class stands the required test I A. Yes, sir. 72. Q. But in the case of wrought-iron guns you could obtain satisfac- tion only by the testing of each particular gun ? A. Yes, sir. I think in the present art of working iron there has been greater uniformity with cast than with wrought iron in large masses. They make gun-barrels of wrought iron with great success. The time may come when they may work wrought iron with like success in large quantities 5 but they have not done it yet in France, England, or the United States, that I have seen. Nobody doubts that wrougfit iron is stronger than cast. There is a great difference in the effects on the metal inside. Cast iron is less injured by the action of the interior of the gun than any metal I have ever seen ; and steel one of the most easily injured. 73. Q. Is that owing more to the concussion or pressure, or to the cor- roding effect of the gases produced by combustion ? A. I think it is the absence of the junction of true iron. Wrought iron almost always assumes a laminar form $ arid between these leaves, as it were, a foreign substance seems to interpose which the gas acts 24 EXPERIMENTS ON HEAVY ORDNANCE. upon. In this examination of Mr. Ames's guns he was not present, being absent in Europe. In examining the interior of the gun, we took a small piece of steel and bent it at right angles, bringing it down to a cutting point less than ^-inch in width. We put it on a light handle and drew it through the grooves of the gun. This would find a little resting place, but when you looked at it it looked like a mirror. We could see that it was not an imperfect weld this was catching, but on the iron itself in its laminar form. When we came to fire it this became very apparent. 74. Q. Was this observation made before or after the firing I A. Before an.d after each fire, sir. Impressions were taken of the whole interior of that gun, and I presume are now in the ordnance department. 75. Q. Was that lamination increased much by the firing ? A. O, very much, sir j very much. I have seen larger defects than that in a cast-iron gun, and the gun stand 1,400 or 1,500 rounds. 76. Q. Have you come to the conclusion that a wrought-iron gun can- not be made of large calibre perfect enough to be used and adopted safely in practice I A. I think you can make the strongest^un we know out of wrought iron. I think there would be a perfect uncertainty in relation to the guns. One of them will stand ; another will not. I think they would be a fa dangerous class of guns until they know more than I think they know now. 77. Q. How do you account for the bursting of those Parrott guns at Charleston and Fort Fisher ? A. I think it occurred from various causes, sir. You never can make a large number of guns out of any material, wrought iron or cast iron, but you will have some guns that have inherent weakness. Some of those guns may have exploded from that cause. My theory has been that the greatest injury came from the projectiles. 78. Q. You attribute, then, the bursting of so many of those guns rather to the projectiles that were used ? A. The majority of them were found to have the projectile burst in them, and, of the remaining part, there was no record to show whether the facts were the same or not. 79. Q. Was not that the difficulty with regard to a great proportion of thos that burst a want of data ? A. Thsre was a very great want ; but in a great many instances there was information. A remarkable thing took place there. An officer, Captain Temple, came up to West Point to see the firing that was going on, and pick up some little ideas in relation to ordnance. I tried to impress upon him that there was a great necessity of using grease not to lubricate the shell, but to burn grease in the gun at every discharge ; and also that the coating of the shells inside should be strictly attended to to prevent premature explosion of the shell. He took command of a vessel and went down there. He attended to both my suggestions, and did not have a premature explosion of a single shell; was the only vessel that escaped it"; nor did he have a gun injured. 80. Q. What was his vessel ? A. I do not recollect the name. 81. Q. Was that at Fort Fisher or Charleston? A. Fort Fisher. I can state another thing: in firing these elongated projectiles, where there is a great deal of powder in the interior of the shell, I fired some to try and find out what was the cause, if I possibly could, of so many shells bursting prematurely. I plugged up the shell and fired a number of them over at the bank across the Hudson. I EXPERIMENTS ON HEAVY ORDNANCE. 25 recovered the shell and cut them open. The powder inside was caked so hard that, in cutting through it, it polished like a piece of slate. 82. Q. Did you ever in your trial of guns burst a gun by bursting the projectile in the gun f A. No, sir ; not entirely to rupture the gun, but to an indentation very deep, and only wonderful the gun should not have yielded. 83. Q. Do you believe a gun could be injured by the bursting of a pro- jectile in the gun without deep indentation on the interior surface of the bore f A. Yes, sir ; I have seen a gun that has been burst where the whole bore of the gun has been swelled outward, and there was strong evidence that the gun burst from its obstruction. 84. Q. Then you would, in every case, expect deep indentation, or forcing out of true line the bore of the gun, if a projectile exploded in the gun! A. Not necessarily. The most natural thing would be that the gun would be spread there, yet it is possible to take place and not do it. 85. Q. Is there any prevailing character of fracture you ever discov- ered in the bursting of these Parrott guns, whether up next the band or at the muzzle f A. I do not know that 1 could say there is any prevailing character. My observation would go to say rather that they had yielded from the vent-hole. The first crack in the metal comes from the rear of the vent as a general thing. 86. Q. Do not they appear to have fractured in all kinds of ways f A. Yes, sir. The first indication you find of any yielding in a gun I do not mean where you explode shells, but the wearing out of the gun is the crack that takes place there. I have seen that in hundreds of instances. 87. Q. What you mean then is, that in long use of a gun the first place at which there is indicated a giving way of the gun is generally there at the vent ? A. It is across, at right angles to the bore ; whereas in smooth-bore guns the line of the first fracture is forward of the vent. The English and French say the same in relation to theirs. 88. Q. Did you fire a 50-potmder gun, made of semi-steel by Mr. Wiard, up to extreme proof ? A. I fired a gun that Mr. Wiard had made as a contractor. My impression is that that gun was not fired up to 1,000 rounds, but between 400 and 500, sir; near 500. This was in 1861. It was the first gun of that kind fired at Staten Island. 89. Q. Did you find that gun deteriorate under these experiments ? A. It stood remarkably well. 90. Q. Did you afterwards fire other guns of the same kind a less num- ber of rounds, and if so, with what result *? A. Yes, sir ; part of them burst. One of those that burst had a false chamber introduced into it. It was on that account that objection was raised to the guns I raised it myself that there was* an attempt -to defraud in making the guns, and therefore tlilre was nothing produced by the makers that should be received for a moment. I stated, as I then believed, that Mr. Wiard knew nothing of it ; but I did not look upon him as the maker of the gun ; he was the contractor and got these guns made. 91. Q. This, if I understand you, confirms your idea that in the case of a steel or wrought-irou gun there is no safety without a trial of each particular gun. Are these guns that were fired and burst at ten rounds similar to that which stood the 480 rounds ? 26 EXPERIMENTS ON HEAVY ORDNANCE, A. Yes. I say in the report that I supposed at that time that Mr. Wiard had no knowledge of that deception ; that only exonerates Mr. Wiard as a contractor. They made a gun that had too long a bore. They wanted to shorten that, and inserted a piece at the bottom of the bore. This gun was blown up. Mr. Wiard disclaimed any knowledge of this thing. I say in the report, "I have no cause to think Mr. Wiard had knowledge of this transaction." 1 did so think at that time ; I do not think so now. I said then, "I believe Mr. Wiard to have acted in good faith in all these transactions" about those guns, but I have changed my mind since, from reports that have come to me since. He says he did not know it at that time, and I do not charge him with knowing it now. But now there is testimony furnished in the Ordnance Office that clears up this point. 92. Q." You have no knowledge since, yourself, on the subject f A. No, sir, nothing ; only reports that have been in existence since. This establishment, where Mr. Wiard had the guns made, got into a muss among themselves, and have charged all sorts of things against each other. I have no knowledge of the credibility of the witnesses. My impression is that one of the reports was that Mr. Wiard avoided a knowl- edge of where defects were in the guns ; that he kept himself aloof from knowing it., 93. Q. I think you said that some of these Wiard guns fired with five- pound charges burst at 10 rounds. A. Yes, sir. 94. Q. Did those that burst show any defects either in the welds or by exhibition of Iarnina3 ? A. I think not, sir; still I would rather go back to those reports, because I might do injustice from want of recollection. 95. Q. Were they of the same size and calibre of the Dahlgreu 50-pounder ? A. Copies of them. 96. Q. The difference being they were of steel. A. My impression is something like this. The finish of those guns was beautiful, and made them a very attractive gun to the eye. Everything appeared well about the gun. We commenced to fire with the intention of going up to 1,000 rounds ; it was dropped short of that, and at that time I thought remarkably well of the gun ; but when this attempt at deception was discovered, the whole thing was dropped. Never was any- thing done about it. 97. Q. Was it the first gun tried that you fired the 480 rounds I A. Yes, sir ; the first gun. 98. Q. Were the other guns there at the same time ? A. I could not say whether they were down at the ground or up at the place where they were being finished. 99. Q. Who selected the gun to be tried ? A. I think it was the first gun finished. I do not think there was any selection about it. I have no remembrance now of any defects being found about these guns that would cause one to be picked out as inferior to the other. There havar been no guns presented to the government that presented a better appearance than they did. 100. Q. You say of those steel guns, the rest of which were fired with 10 rounds, that some burst and some did not ; do you recollect how many burst and how many stood the test ? A. I could not say how many were fired. I have a sort of glimmering idea that two burst. 101. Q. How do you account for the bursting of the Wiard 50-pouuder, which seemed to be perfect in its structure ? EXPERIMENTS ON HEAVY ORDNANCE. 27 A. I think those guns were made out of different material. I did not think so at the time, but since then 1 am inclined to think the same mate- rial was not used for making all the guns. 102. Q. You think the guns which burst were npt made of the same material as the ones that stood the test ? A. I could not say that, sir, because the thing was dropped right there, and no examination was carried on about it. But there is a report in circulation that the last forgings were made of wrought iron. 103. Q. Was it your theory to account for the bursting of these guns that there was a variety of material put into the gun in any instance, which burst, or whether the gun burst was made of a material different from that which stood the ordeal ? A. Not at that time ; because I supposed everything was perfectly honest and straightforward up to the moment we found the guns had been tampered with, and then the thing was dropped. I never prose- cuted the investigation, but since then this idea of different material has been suggested. If that is so we may account for it. 104. Q. To reduce the length of the bore, then, you found they had filled up the end of the bore next the breach I A. Yes, sir; therefore the true thickness of the breach was at this point less than it should be. 105. Q. Was that done in the case of the one that stood the test ! A. O, no, sir ; only done in one gun ; no probability that it was extended to any one but that. 106. Q. Then you did not prosecute the trial because this was found to be the case with one of these guns? A. Yes, sir ; that is an old established usage more than 20 years old that where any defect in a gun is conceded by the contractor, it vitiates the whole contract. 107. Q. A discovery of that kind might properly affect the validity of the contract, or the acceptance of the gun from that contractor, but would not bear on the question of the value of the gun which stood the trial ? A. Not at all. 108. Q. What is the objection to the gun that did not stand the trial ? A. Nothing ; only it fell under this category of rejecting everything that came from makers that attempted to deceive you. But whether a good gun could be made on that principle is not brought in question. 109. Q. State whether the blocking or filling up the rear part of that bore was a cause of weakening the gun 1 A. I should rather incline to say yes. There is generally given in the construction of all guns, as in everything else,. a little excess for safety. Whether this gun was heavy enough at the breech to admit of the loss of two inches might be a question. I could not tell without going into a minute calculation. 110. Q. What depth of metal would you think required in a gun of that character in order to give sufficient strength to the breech from the bottom of the bore through to the breech of the gun ? A. I should think a less amount would answer than was in that gun. I think the thickness was rather excessive in the design of that gun. 111. Q. Was that one of the guns that burst ? A. Yes. 112. Q. I understand that these guns which were produced by this contractor were rejected, the whole lot of them, because there was found in one of them which burst, an addition of metal at the rear end of the bore, put there for the purpose of reducing the length of the bore ? 28 EXPERIMENTS ON HEAVY ORDNANCE. A. Yes, sir ; it was on account of this deception that the guns were thus all rejected. 113. Q. Do you consider that as touching the question whether a gun of that kind might or might not be a valuable gun ? A. Not at all, sir. 114. Q. It is a matter which affects the question of receiving guns from that particular contractor ? A. Yes, sir. 115. Q. How do you account for the bursting of the Wiard 50-pouiider, which showed perfect structure, and the endurance of a cast-iron gun, made of metal only one-fourth of its tensile strength? A. I cannot account for it, because that subject .was never exhausted. The investigation was dropped, and I never recurred to it. The merit of the guns, as guns, I have never taken up from that day to this. 116. Q. Then this trial, in your opinion, has not determined the merit of these guns as guns, but only the claim of the contractor as a contractor f A. That is all. 117. Q. You never considered your trial of the guns as completed, in view of satisfying yourselves as to the merits of the gun itself? A. It was not, sir ; you will find the report was closed abruptly by this occurrence. A final decision never was made of those guns as guns. 118. Q. You' say you suppose they were not all made of the same material I * A. I have supposed so since that report was written ; since the disturb- ance referred to took place. 119. Q. But you have no knowledge on the subject f A. None at all. 120. Q. State whether Mr. Wiard was present at the trial ; and if so, what explanation he gave of the bursting of the guns J ? A. Mr. Wird has given me so many theories at times that I truly do not recollect just what particular theory he then advanced. I do recol- lect that we kept talking pretty much all the time we were down there. 121. Q. Do you recollect whether he did or did not explain that it was, in his opinion, owing to the expansion by heating the gun? A. Those were subjects, generally, of constant conversation with us both: All kinds of theories were discussed there by us, and if Mr. Wiard says he told me that at the time, I should not doubt that he did, but I have no recollection of it ; I recollect his discussing these things. WASHINGTON, November 11, 1867. STEPHEN V. BENET sworn and examined. By the CHAIRMAN pro tern. 1. Question. State whether you are in the United States army, and your rank ? Answer. I am a major of ordnance in the United States army, and brevet lieutenant colonel. 2. Q. Did you make a proof of the powder used in the experiments with Mr. Ames's gun ? A. Two samples of powder were sent me from New York recently, by Colonel Laidley, with the request that I should get the initial velocity and pressure on the bore. Whether I learned at that time or was told afterwards it was powder that had been used with the Ames gun I do not remember; but I believe it was the powder. I made the test 4? that powder in the usual way we test powder there for the service, and sent EXPERIMENTS ON HEAVY ORDNANCE. 29 him an official abstract from my record. Beyond this I don't know. The following is the official record of the test that I made with those samples : Powder Initial velocity. Strain on gun. Date. g P 1 a 5 M | 1 1 r <w 5 . 'S S & o S O &.C | I , o . c 5 | 1 1 S3 '" 5 i i 2 . 5 i a IS i 1 1 1866. Aug. 10 . 1. 7212 Mixed, from Little. . Aug. 8 18.3 1360 9 87 300 No. 5 to mortar. Sept. 13 1. 6504 No. 7 None Sftnt. 11 21.8 1142 4 77 300 20.5 1214. 9 79, 800 WASHINGTON, November 11, 1867. THEODORE T. S. LAIDLEY sworn and examined. By the CHAIRMAN pro tern : 1. Question. State whether you belong to the army of the United States, and if so to what arm of the service, and what is your rank? Answer. I belong to the ordnance corps, with the rank of lieutenant colonel of the United States army. 2. Q. What is your residence and where are you now employed? A. I am stationed at Governor's island, New York harbor. 3. Q. How were you employed during the war, as an ordnance officer? A. During the war I was in command of Frankfort arsenal a portion of the time, and afterwards in command of the Springfield armory. 4. Q. For what length of time and between what dates were you at Springfield armory"? A. Eighteen months. I arrived there on the 27th of October, 1864, and left there the middle of May, 1866. 5. Q. Have you been engaged in testing heavy ordnance at any time during the war? A. I have. I had, just before the war, fired a pair of Eodman guns at Pittsburg, and three years ago I was engaged on the board that fired Mr. Horatio Ames's 7-inch gun. 6. Q. Have you also had experience in the testing of cannon powder? A. I have. While 1 was at Frankfort arsenal I was inspector of powder. 7. Q. Will you state what the proper proportions of cannon powder are, and what is the standard proof powder used for heavy ordnance? A. Cannon powder is composed of saltpetre 75 parts, charcoal 15 and sulphur 10. The composition of all powder is the same, and varies principally inathe size of the grains and somewhat in the density. In that for heavy guns, the size of the grains is made largest. The stand- ard proof of cannon powder is : 10 pounds are fired in an VIH-inch gun with solid shot, and the initial velocity is taken and also the pressure on the Square inch of the bore. There are two diiferent kinds of powder for cannon : that is, the cannon proper and mammoth powder. The cannon powder is used for the larger guns, and for the XV-inch guns they use r the mammoth powder. The initial velocity for the cannon powder is about 1,225, as I remember. It has been some time since I looked over the figures. The pressure per square inch is about 40,000 pounds. The 30 EXPERIMENTS ON HEAVY ORDNANCE. mammoth powder varies more than the cannon powder. It would give, fired in the VHI-inch about 1,050 feet initial velocity, and a pressure of not over 10,000 pounds. 9. Q. Do you regard soft powder as suitable for large guns, to give them a proper velocity ? A. No, sir; soft powder would not be suitable for large guns. 10. Q. Is there any difference in the gases, the result of combustion, between coarse and tine powder made from the same constituents ? A. No, sir; I should think not. t 11. Q. Is there any difference in the quantity of gas resulting from the com burtion of coarse or fine powder? A. I should think not. 12. Q. Which would act with the greatest force upon the square inch of the interior surface of the chamber filled with either the coarse or fine powder, if the chamber were strong enough to resist the expansion of the gases? A. The fine would act with the greater force on the chamber. 13. Q. Is there any residuum from powder which is not combustible? A. O,yes. 14. Q. Which leaves the greatest quantity of residuum, coarse or fine powder? A. I should not think there would be any diiference. It is more the circumstances under which the powder is exploded than the mere ques- tion of. tli e size of the grain that determines this. 15. Q. Which will project a shot furthest from a XV-inch gun coarse or fine powder, taking pound for pound? A. The size of the grain would have to depend 011 the density of the grain. If you made the grains very large, then you might make them softer than if you used a smaller grain. In firing a XV-inch gun the point is that you must not endeavor to impress the 'full strength of the shot on the powder too rapidly. The powder must burn progressively, giving the ball an opportunity to move as the force is gradually developed. 16. Q. Which of those would be furthest projected with the same charge, in your opinion, solid or hollow shot? A. The hollow projectile would start with a greater initial velocity, but it would more rapidly lose its velocity than the solid shot. In high elevations, with proper charges, the solid shot would probably give greater range than the shell. 17. Q. Which, then, would penetrate the greatest thickness of plate at a given range, in your opinion ? A. The penetration is a question of the mass into the square of the velocity. That would penetrate the furthest vrhere the mass into the square of the velocity was greatest. You might arrange it so that either the shell or the shot would penetrate the further. 18. Q. Then hollow shot would be projected further also if the cavity were filled with lead, with the same charge ? A. That would depend upon the charge you gave it. 10. Q. With the same, would the shell, if the cavity were filled with lead, be i)rojected further than it would be if the cavity were not filled with lead? A. I think that would depend very much on what charge you used. 20. Q. Explain the distinctinction you would make in the charges in order to produce the effect in one case whicji would not be in the other as between a small and a large charge. A. With a small charge the hollow shot would probably go further than a very heavy projectile with the same charge, but when you come EXPERIMENTS ON HEAVY ORDNANCE. 31 to fire very large charges then the heavier projectile would go further than the lighter. It is owing to the fact that the resistance of the atmosphere varies in a proportion rather greater than the square of the velocity. When the velocity increases very much, the square runs up very rapidly, and the retardation by the atmosphere is very great. With a less velbcity it is not so great. 21. Q. What force is it that ejects the shot from the gun ? A. It is the expansive action of the gases in the gun. 22. Q. In your opinion is all that force of the powder expended in ejecting a hollow shot from a gun ? A. That would depend very much on the length of the bore and the size of the charge. You might put in such a charge that a portion of the powder would be thrown out unburned, as is often the case. 23. Q. In your opinion is the pressure of the powder per inch upon 'the interior surface greater with a solid shot or with a hollow shot ? A. The heavier the projectile the greater would be the strain upon the gun. , 24. Q. How heavy, then, in your opinion, would the projectile from a XV-inch gun have to be in order to attain the greatest result in penetra- tion of iron-plating? Have your experiments led you to a conclusion about that ? A. Make the mass into the square of the velocity the maximum and you get the greatest penetrative effect. That is, of course, taking for granted that your projectile has the same figure, the same point. If the projectile has a different ppint, I mean front termination, that would have something to do with the penetration. A round shot Avould not penetrate as far as a more pointed one. 25. Q. Could you make a projectile, as heavy as the gun itself, for instance, penetrate as great a thickness of plating as a hollow shot of the ordinary weight ? A. I should not think it would be practicable. 2G. Q. You said that you had been engaged in the trial of Mr. Ames's guns? A. Yes, sir. 27. Q. Where was it ? A. At Bridgeport, Connecticut. 28. Q. How many times did you fire that Ames gun ! A. Seven hundred times. 29. Q. What charges of powder and shot did you use ? A. Charges varying from 19 pounds to 30 pounds, with shot varying from 100 to 125 pounds. 30. Q. What velocities did you get ? A. It was a difficult matter to obtain the velocity, on account of the imperfect projectiles. The base or fragments from the projectile would fly off, and cut the Avires ; so it was a difficult matter to tell whether the wire was cut by the ball or cut^by a fragment ; and on that account we did not attempt to get the initial velocity with the highest charges. 31. Q. What were the charges? A. Most of the charges were with 19 pounds of powder. We varied it, firing 150 times with 25 pounds of powder, and as many as six times with 30 pounds of powder. Most of these were with the powder known in the army as No. 7 powder, whi*ch is a smaller grain than cannon. 32. Q. What was the range of the gun ? A. The ranges w^ere not determined very satisfactorily fired over the water and determined by plane-tables, I think. A little over five miles was the greatest range we got. 32 EXPERIMENTS ON HEAVY ORDNANCE. 33. Q. Had you a base line long enough to give you the exact measure- ment of the range ? A. Not with great accuracy ; and the persons that were using the plane-tables were not accustomed to the work. 34. Q. In your opinion the charges that were used have given a greater velocity and range than your figures in the report made indicated 1 ? A. I supposed that they would. The gun was considerably worn before the ranges were taken, and the windage was greater. That would cause a diminution of the ranges. 35. Q. Would the charges, for instance of 30 pounds of powder, give you greater range and velocity than the 19-pound charges? A. It is fair to suppose so. Yes, sir ; I should think so. 36. Q, That was the firing in 1864, was it not? A. Yes, sir. 37. Q. What was the size of that gun? A. It had a 7-inch bore, and weighed about 19,400 pounds. 38. Q. Did you superintend the firing of the Ames gun in 1866 the 100-pounder? A. I was associated with Commodore Hunt in the proof of that gun also. 39. Q. Had the powder been proved that was used in that trial ? A. Yes, sir. 40. Q. What pressure on the gun did that powder give, and what velo- city? A. I do not remember the velocity. I remember that the pressure of one of the powders used was 87,000 pounds per square inch. That was not the powder used in 1864. 41. Q. What was the difference between the powder used in 1864 and that used in the 100-pounder in 1866? A. The powder used in 1866 was a much quicker powder, and pro- duced a much greater strain on the gun than that used in 1864. 42. Q. What range did that 100-pounder give in 1866? A. The ranges of that were extremely unsatisfactory. We had three stations; and the ranges as given by the two stations did not correspond with each other; and I do not remember what the range was. I remem- ber the fact that they were very unsatisfactory. I was in favor of trying it over. 43. Q. Was the measurement unsatisfactory to you, or the range shown by the. gun? A. We had three observers, either two of which would make a com- plete set of results; and then, with the three observers, we ought to have three separate and distinct ranges. If the experiments were accu- rately conducted those three would have agreed very closely. They did not agree, but varied so much as to create doubt of their accuracy. 44. Q. Bo you think the rifling of that 100-pounder was suitable rifling for a gun of that calibre? A. I do not; I do not think the twist was quick enough. 45. Q. Do you think the range would have been greater with a greater twist in the rifling? A. I think we might have got a chance shot with this gun where the range might have been as great as it would have been with a quicker twist, because the friction would be less; but the twist was not sufficient in all cases to keep the ball point foremost; and in that case the range ordinarily would not be as great as it would be' with a quicker twist. 46. Q. Did you fire the gun at a high elevation? A. We did; as high as the carriage would admit. EXPERIMENTS ON HEAVY ORDNANCE. 33 47. Q. Are you accustomed to fire guns at so high an elevation in proof? A. We do not ordinarily do it in proof? 48. Q. Why did you fire at so very high an elevation at that time ? A. For the purpose of obtaining the range ? 49. Q. The elevation at which you fired that gun is a stronger proof than you ordinarily subject guns of any kind to, is it not? A. Actual experiment does not show that the strain is very much increased by increasing the elevation. The ordnance department made a series of experiments at Old Point Comfort with a view of testing that, and found the additional strain on high elevations is very trifling. 50. Q. You think that experiment or experience does not prove that it makes any very great difference. A. Those are the actual experiments performed by the ordnance department, by the pressure plug. Those are the results given by the pressure plug. 51. Q. How many of those 100-pounders were you on a commission to examine? A. I think there were nine or thirteen, I am not sure which. 52. Were the guns fired in 1864 and those fired in 1866 of precisely the same calibre? A. There was only one fired in 1866. 53. Q. You were on a commission to examine how many of them? A. I am not sure whether there were nine or thirteen. They were 7-inch guns ordered by Mr. Lincoln. 54. Q. I was under the impression there were three or four tested in 1866? A. In 1866 we fired a single gun, at Bridgeport. 55. Q. That represented how many of these guns eight or nine? A. I am not sure about that. Those were navy guns. 56. Q. State in general terms what your report was. A. We reported that the Ames gun, when the welds were well made, was a stronger gun than any that had ever been presented in the ser- vice; that we did not fire them all, and were therefore not prepared to say whether the other guns were good guns or not; that we could not pretend to say, from firing one gun, what would be the quality of the guns that had not been tested at all; and stated that it would be necessary to fire them before we could determine upon their merits; after they had been fired to test their strength, we thought they ought to be tested by firing service charges to ascertain their durability. 57. Q. You of course did not feel authorized to go into any question that might arise under the contract for making the guns? A. We were not called upon to decide any question of that kind. 58. Q. Did you mean that your condemnation of the guns should touch the question whether they should be paid for or not whether Mr. Ames was entitled to be paid for them ? A. Not at all. 59. Q. Is it possible, in your opinion, to make a weld of a wrought- iron gun so perfect that it will not be a weak spot in the gun? A. I think it can be done. 60. Q. What do you think, then, of the principle of manufacturing guns as Mr. Ames has undertaken it? A. I do not know whether Mr. Ames can make a perfect weld uni- formly or not in such large masses. 61. Q. Then, when you say that you think a weld can be made so perfect as not to leave a weak place in the gun, you have no experience that would extend that to very large guns? Rep. No. 266 3 34 EXPERIMENTS ON HEAVY ORDNANCE. A. No, sir ; for instance, we weld musket barrels successfully, though we do come to one occasionally that is not welded. 62. Q. Are you led to believe that a weld in the construction of a gun so large as these 100-pounders can be made so perfect as not to leave a weak spot in the gun? A. It can be done ; but whether it can be done every time or not I do not know. For instance, in the 3-inch guns we weld the trunnions on to the body of the gun. I never knew one to give way there. 63. Q. It is usual, at least in the naval system of ordnance, and per- haps with the army, to accept guns upon a trial of one of the lot. If it stands the test, is not the lot received without trying each gun ? A. In the land service we fire each gun ; but we do not fire it to extremity. 64. Q. You do not submit each gun to the great trial test of a thousand rounds, for instance? A. O, no. With cast-iron guns they take one gun and fire it a thousand rounds, and then afterwards make others as nearly like that as it is pos- sible to make them, and accept them on a very trifling proof. 65. Q. You think, then, in the case of wrought-iron guns it is more important than even in the case of cast-iron guns to submit every gun to a test? A. I think it would be necessary to give each individual gun a more severe test than in the case of cast iron. 66. Q. And to give a thorough test to each gun before you would condemn or accept it ? A. I would pursue very much the same course we do with the musket barrel. Every one we adopt we fire with an excessive charge, in order to test the question whether it is welded or not. If it is not, it gives way. If it is thoroughly welded, it does not give way. I think it would lie necessary, in proving wrought-iron guns, to fire each one with an excessive charge to test that question, whether it was welded perfectly or not. 67. Q. What gun have you ever ,tried, if any, that you think equal to this Ames gun? A. I have never fired any gun so large as the Ames gun which I think possesses as much strength as the one that we tested. I fired a small gun made of wire by Dr. Woodbridge, which I think probably was as strong in proportion as Mr. Ames's gun. But that was a very small gun. 68. Q. Could that system of manufacture be applied to very large guns? A. The inventor thinks it can. 69. Q. I am asking for your own opinion ? A. I do not know ; have not sufficient information to give an opinion on the question. 70. Q. The Ames guns are the largest wrought-iron guns you have ever tried? A. They are. 71. Q. Are you well acquainted with the Parrott gun ? A. I have had very little experience with the Parrott gun. 72. Q. Have you never tested any of them? A. I have never. 73. Q. Do you suppose that a Parrott gun of the same calibre would stand 20-pounds charges 10 times with the same powder you used in the trial of the Ames guns, giving 87,000 pounds pressure on the bore of the gun? A. I do not think it would. EXPERIMENTS ON HEAVY ORDNANCE. 35 74. Q. What would be the comparative difference of velocity, as given by the 20-pounds charge and the 10-pounds charge of powder? A. I 00 not think you could get any rule. 75. Q. Do you think there was any difficulty as to the range, arising from the kind of powder that was used in those experiments at Bridgeport ? A. No ; I should think not. At the experiments in 1864 we used two kinds of powder, both No. 7 and No. 5. 76. Q. Was there nothing in the character of the powder used giving it a greater tendency to burst the gun than powder ordinarily used! A. In 1866 the powder was a very bursting powder; but if the gun should resist it as it did, there was so much of it, I should think it ought to give a very high velocity and great range* 77. Q. It was in 1866 that you used a powder appertaining more to the character of a fulminating powder than the other? A. Yes, sir. 78. Q. I think you stated that you did not think this Ames gun had the best rifling to adapt it to the greatest range or effectiveness? A. I did. 79. Q. What change would you have suggested in that rifling? A. I would have made it quicker given more rotary motion to the ball. 80. Q. Did you ever have anything to do with, or suggest, rifling of that kind? A. Nothing. 81. Q. Do you know who directed the rifling? A. I do not know. I understood the government ordered the rifling, but I do not know that to be the case from my own personal knowledge. 82. Q. Are you acquainted with the Armstrong gun? v A. Only from books and newspapers. 83. Q. Do you consider thztt better than any gun we have? A. I do not think it as strong a gun as Mr. Ames's gun. 84. Q. What would be your opinion of the comparative merits of a 9- inch rifled gun and a 6^ calibre gun, loaded with proportionate charges, fired as against an enemy, when fired at the highest velocity ? A. It all narrows itself down to the proposition I have already stated, one-half the mass into the square of the velocity is the work done. It all depends on that. 85. Q. It is your opinion all these questions can be settled with mathematical accuracy without reference to experience and whatever we learn by the practical use of the guns ? A. Captain Noble, of the English service, has made a series of exper- iments, and finds that you can calculate with very considerable accuracy the effect of any shot. We feel much more sure of all these tests, of course, after we have had the actual experiment performed. But the English government has made a large series of experiments, and that is the conclusion Captain Noble comes to that we can calculate with very great accuracy the effect of any shot projected with any given initial velocity. 86. Q. Have we any rifled gun that can stand charges that will give the greatest velocity to the shot of 8, 9, or 10-inch calibre? A. We have no rifled guns in the service that I know of except the Parrott guns and some experimental cast-iron guns of 8 and 12-inch bore. It has not yet been tested thoroughly what endurance these guns will have under high charges. 87. Q. I was asking for your opinion. Do you believe we have any gun, say from 8 to 10-inch calibre, that is strong enough to resist the charges that will give the greatest velocity to the shot ? A. I do not think we have. 36 EXPERIMENTS ON HEAVY ORDNANCE. 88. Q. I suppose it is your opinion that is very desirable ? A. O, very. 89. Q. Do I understand you to say this Ames gun is the strongest that you have ever tested, tried, or know anything about 1 A. When the welds are well made it is the strongest gun I have ever known. 90. Q. Did you ever send more than one sample of the powder used in these experiments to Captain Belief? A. I sent him a sample of each, and the intention was there should be enough to fire three rounds of each powder. The powder used is known as No. 7 experimental powder, of 57,000 pounds per square inch. (It is erroneously printed in the report 5,700 pounds.) 91. Q. You say you sent a specimen of each ; do you mean that used in 1864 and that^used in 1806 ? A. Yes, sir ; we usually send samples enough to fire three charges. We sent samples enough to fire three rounds of that in 1864, and the same of that in 1866. Wliat we used in 1864 was all the same; but whether the powder used in 1866 was all the same I cannot say. 92. Q. What is the proof reported to you by Captain Bene'tf A. Eighty-seven thousand pounds per square inch. 93. Q. Do you consider the kind of powder you used in 1866 suitable powder to use in a gun, except it be to see whether you cannot burst it ? A. I do not. 94. Q. It is not such powder as you would use in practice at all ? A. No, sir. 95. Q. It was used, then, as an extreme fulminating powder, in order to produce the greatest strain ? A. I cannot say what it was used for. The powder was supplied, and I was merely sent there to assist Commodore Hunt in the firing. 96. Q. What is the standard proof of powder used in the army for velocity and pressure on the bore of the gun ? A. Our cannon powder should not give a pressure higher than about 40,000 pounds per square inch. 97. Q. Do you know what the rule is in the navy? A. I do not think in the navy they take into consideration the pressure on the bore, though I cannot state certainly. 98. Q. You speak of the diificulty of making a weld, in the construc- tion of a large gun like this, so perfect as not to leave a weakness in the gun at that point ; I will ask you whether the fissures or cracks in a gun made by welding together wrought iron are, in your opinion, always the result of imperfection in the welding, or whether they are not as likely to be produced by the unequal contraction of the iron in the mass of the gun ? A. We never discovered any fissures except rings, and I supposed those were caused in all cases by imperfect welds. 99. Q. If there was unequal contraction in cooling of one of these rings, might it not produce a fissure ? A. I do not see how it could produce a fissure such as we found. The guns were manufactured by a series of rings put together one on top of the other. 100. Q. Might' there not be a difference in the density of the metal of different parts of the same ring I A. There might be. 101. Q. Would not that produce unequal contraction when the ring came to cool? A. It would. EXPEKIMENTS ON HEAVY ORDNANCE. 37 102. Q. If in consequence of contraction there was an opening of the seam, making a fissure, or a giving way of the metal anywhere, would it not be more likely, in your opinion, to be at the point where the two rings met and the weld took place than at any other ? A. I do not see that it would. It is understood that the gun is actu- ally forged hollow, and has an opportunity to contract. 103. Q. When you speak of the pressure of powder on the square inch will you state what instrument you use for determining that pressure 1 A. We use what is known as Bodman's pressure piston. It is described in the Ordnance Manual. 104. Q. Do you think that a reliable or infallible instrument for such measure ? A. I do not think it is infallible. It is the best that we have. 105. Q. Does that give the pressure actually, or what you call the momentum of the gases? A. There is a difference of opinion about that. 106. Q. I want yours. A. I think it gives it very nearly. It is undoubtedly the momentum of the part of the piston that moves ; but the distance this piston travels is very small. 107. Q. Capable of being observed, though, accurately? A. O, yes. 108. Q. Did I understand you to say that the velocity and range were not determined by the highest charges that you used ? A. The velocity was not determined by the highest. The range was. 109. Q. Was the velocity or was the range, either or both of them, greater for the larger charges that were used in these experiments'? A. We only determined the initial velocity, I think, for the 19 pounds of powder, not for the larger charges. Owing to the difficulty which I speak of, the fragments of the shell flying oif and breaking the wires, we did not regard it as reliable, and therefore gave it up. 110. Q. Do you know anything about the experiments with the Par- rott guns at Charleston, and the practical use of them there! A. I do not, except what I have read or heard nothing from actual knowledge. 111. Q. Do you know whether the velocity obtained with these experi- ments with this gun was greater than that obtained at Charleston from the Parrott gun with smaller charges, with the same elevation? A. You can but know, or think, at any rate, it was greater, because the charges at Charleston must have been less. 112. Q. Were the samples of powder sent by you to Captain Benet the same that were used? A. They were. WASHINGTON, D. C., November 12, 1867. NORMAN WIARD re-called. By Mr. CAMERON : Question. Do you know what varieties of calibres and ammunition were introduced in the service,during the war, and have you any opinion as to the importance of establishing a uniformity of calibres and ammu- nition ? Answer. I am familiar with the calibres of our guns ; and when I relate some of the facts within my knowledge I think you will agree with me that our ordnance departments have got our small-arms, artillery and 38 EXPERIMENTS ON HEAVY ORDNANCE. guns into most reprehensible confusion, for want of uniformity in calibre and ammunition. The ordnance departments of France and England have no greater differences embodied in the systems they have adopted than there is between the two branches of our service. The calibres, models, chambers, and ammunition of the navy are utterly unlike those adopted for the army. The navy rifled 12-pounder boat howitzer has a calibre of 3 ^ inches, while the army 12-pounder rifled guns are of the calibres of 3 inches, 3 T 2 ^ inches, 3^, inches, and 3 y^ inches. The navy 12-pounder has a parabolic form, of chamber, while the army gun has either no chamber or it is cycloidal. The navy 12-pounder smooth-bore, although of the same calibre as the army gun, has a different form of chamber. Apparently each of these chambers has been devised to prevent the use of navy ammunition in the army gun or army ammunition in the navy gun. The models of the two guns are entirely different, and neither will go on the other's carriage, the army gun being furnished with trun- nions and the navy gun having the loop and loop bolt of the old carro- nade. The sights are of an entirely different kind in the two guns, and so graduated as to make it impossible for a navy gunner to use an army gun, or an artillerist of the army to use a navy gun for an emergency one being graduated to seconds of time and the other to degrees of eleva- tion. The 20-pouuders and 30-pounders of the navy are different from the army guns of the same kind, the navy guns having a shark's mouth for the breeching, which is not on the army guns. The navy Dahlgren 20-pounder, 30-pounder and 50-pouiider are of a different model, calibre, form of chamber, and kind of rifling from any other gun in the navy or army, all purposely different, seemingly, to insure the use of a certain kind of projectile which Captain Dahlgren claimed to have invented, being essentially the same as the so-called Dyer projectile, but which was found latterly to have been used and patented by others long before. The Dahlgren, like the Dyer, was abandoned after large numbers of them had been produced. The Dahlgren 50-pounder has a calibre of 5 JL inches, as' if the inventor, from paucity of ideas, could only produce a new diameter of calibre which no other person had thought of. The army 3 inch gun, it has been said, was rifled in a peculiar way to adapt it to the Dyer projectile, which being condemned, it was happily found could be used with the Hotchkiss projectile. The navy have, then, a 60-pound er Parrott, adopted, as shown by the lucid explanation of Cap- tain Wise, Chief of Ordnance, so as to have something between the 30- pounder and the 100-poimder; and no other reason is. given for its adop- tion ! The navy has VHI-inch, IX-inch, Xl-inch and XHI-inch smooth- bores, as if the navy chose odd numbers of inches for luck. The army sm oo th-bores are 6-inch, (32-pounders,) 8-inch (64-pounders,) and 10-inch, (130-pounders.) The navy chose the old Konian numerals to describe the calibres of their guns, probably because the army had some fanciful pre- emption right to the more common figures. In the guns adopted and actually issued to service in the two branches of the service, there is not a single example of uniformity, in either rifle or smooth-bore, in the 20 calibres adopted of those below the calibre of the 30-pounder. I append a tabulated statement of calibres, models, weights, chambers and charges. How long it has taken two complete organizations of ordnance officers, educated at the public expense, experimenting, with the treasury of the United States to pay the bills ; what the cost of the effort has been in money ; how much treasure has been wasted in furnishing the arms to the extent to which they have been supplied after they were adopted ; how much life of citizen soldiers and honor of the nation have been misdi- rected and wasted, it is not within my power to even estimate. I am, EXPERIMENTS ON HEAVY ORDNANCE. / 39 however, confident that no example of such imbecility of invention and paucity of practical results ever before attended an effort conducted with so much flourish, on so grand and expensive a scale, with objects so important, and where the class of persons charged with so important a branch of the public service for so many critical years have brought their departments into such confusion. They are entitled to the execrations of every citizen, and would receive them, too, were the facts known. The calibres of small-arms and the ammunition for them although it would seem impossible, so minute must be the differences where the greatest is .70 of an inch are as diverse as in the field, siege and heavy guns, and similar want of uniformity exists. In order to find divisions for sufficient diversity the dimensions of calibres are given inhundredths or thousandths of an inch, and our muskets and carbines alone range* from .40 to .69 We have an Enfield rifle of .57 and a Springfield of .58, but no instruments common in the hands of inspectors or soldiers for determining the difference. Hence, during the war the army has fre- quently found itself on the field of battle facing the enemy with ammu- nition one-hundredth of an inch too large to be inserted in the gun. About 20 different calibres of ammunition were furnished the Burnside expedition, from .44 to .69; and, lest one transport carrying all of one calibre should be lost, each vessel had to be supplied with an assorted cargo made up of certain proportions of the whole. It was the same with the Banks expedition, making it necessary to stow away the cargo with considerable skill, so that any of the various kinds could be got at upon the recurrence of an emergency, a ]1reliminary caution likely to be over- looked in the hurry of the embarcation of an army; the consequences of neglecting which and no cautionary order by the ordnance department is given on such an occasion are easy to conceive. A great many hun- dred thousands of Springfield muskets are now to be sacrificed to uni- formity of calibre. The ordnance department in this, as in the question whether it was better to have breech or muzzle loaders, were undecided during the war, only concluding* 1 their cogitations when the emergency had passed. In 1861, when every tyro knew that a breech-loader was best in fact nobody but an idiot or an officer of our ordnance depart- ment would ever decide otherwise the Chief of Ordnance of the United States held and advocated that "a Harper's Ferry smooth-bore muzzle- loading gun, with buck and ball, was the best arm that could be placed in the hands of a soldier;-' and asserted he would have no such gun as a breech-loader in service because it would require a mule to carry the ammunition for each soldier it would be shot away so fast ! Now it is proposed to alter all the Springfield rifles on hand to breechloaders; and in order to get uniformity of calibre, i. e., to have the musket con- form to the calibre of the carbine, the barrel is to be reamed out, another barrel inserted, the new lining is to be bored out, straightened and rifled ; the breech of the barrel is to be bedevilled by the insertion of a compli- cation of parts, and thus a new gun is to be made. But, gentlemen, this will cost more than to make a new gun; and that is not all, for although it is an approach to uniformity of calibre, it brings us no nearer to uni- formity of ammunition than we were before, because the carbine charge is not sufficient for the musket, and when this improvement is adopted we shall have another slight diversity, as in the case of the Enfield of .57 and the Springfield of .58, for the chamber of the carbine is not long enough for the musket cartridge, and the carbine charge is not heavy enough for the breech-loading musket. 40 EXPERIMENTS ON HEAVY ORDNANCE. WASHINGTON, November 12, 1867. Q. A. GILLMORE sworn and examined. By the CHAIRMAN pro tern. : 1. Question. Will you state if you are in the military service of the United States ; if so, in what arm of the service and with what rank ? Answer. 1 am in the service of the United States, major in corps of engineers and brevet major general in the United States army. 2. Q. Were you in command at the siege of Charleston ? A. Yes, sir j in command of the besieging forces. After the April attack by the navy I had command of the land forces. Will you state how many men composed your army and what was the plan of attack there ? When I assumed command in June, 1863, I found the troops occupy- ing the coast from St. Augustine, Florida, to the north end of Folly island. I got together 10,000 men in round numbers, for offensive ope- rations, leaving the most important points of the coast garrisoned in sufficient force for security. The plan of operations was to make a descent upon Morris island, carry its defences by assault or siege, and then demolish Fort Sumter so that the navy could enter the near harbor and move up to the city. A siege of Charleston by land was never con- templated in my instructions or in any of my plans. This plan the General-in-chief informed me grew out of a request by the naval authori- ties for assistance in making another attack upon Charleston. They desired Fort Smnter, which had repulsed them in April, to be eliminated from the fight. By Mr. CAMERON : 3. Q. What sort of gnns had you there in use ? A. All the heavy guns were Parrotts ; I had field batteries besides. 4. Q. What were the charges used in the different calibres of these guns ? A. I do not recollect j I used the charges prescribed by Mr. Parrott, if that would be an answer, in all cases. 5. Q. What powder did you use in the 100, 200, and 300-pounders ? A. We called it " cannon" powder. It was not mammoth powder. I think we had a little mammoth powder for a few trials, but we used cannon powder. 6. Q. Was that furnished you I A. Yes, sir ; furnished us by requisition on the Chief of Ordnance. 7. Q. What is the velocity and pressure on the bore of the gun with this powder ? A. I cannot tell you that. 8. Q. Can you tell me what 'does No. 7 powder give I A. No, sir. 9. Q. Nor No. 5 ? A. No, sir ; that requires a technical knowledge which I do not pos- sess just now. I have known at various times, but I forget it. The smaller the powder the greater the pressure generally ; but I do not recollect the pressure in pounds. 10. Q. What range did you get from 100, 200, and 300-pounders I A. The 200-pounder fired from Morris island to the city of Charleston. I should have to refer to my report to see the number of yards. I only know it was over 7,000 yards, because we had means of knowing that the projectiles went into the city, and it was 7,000 yards to the nearest point. EXPERIMENTS ON HEAVY ORDNANCE. 41 11. Q. Did they go into the city to be effective ? A. The shells from the first gun we fired went through houses ; did not accomplish any immediate military effect. 12. Q. What is the cost of placing a " Swamp Angel" for use? A. It is difficult to give the cost of the battery. There were $4,000 worth of sand-bags used in it. That was the only material I had to buy. The timber we cut in the woods on the adjoining island and carried up there. 13. Q. What time did it occupy ? A. It occupied about three weeks, I think. 14. Q. And how many men were employed at it 1 A. I suppose there were two or three parties of fifteen or twenty men apiece ; some carrying sand-bags, some floating logs down to the place, some cutting logs on the adjacent island and hauling to where they could be floated. They were generally towed across the narrow river by a steam-tug. 15. Q. How far was it placed from the city ? A. Seven thousand yards from the nearest point. 16. Q. W T hat damage did it do to the city while under your direction ? A. That gun burst after the thirty-sixth round. I judge that three- fourths of all the projectiles fired from that piece entered the city. I did not put another gun there. 17. Q. To what do you ascribe that failure? A. The gun was fired at a very high elevation, which gives increased strain upon a gun. Exactly how much additional strain the gun has to sustain at an elevation above the horizontal I do not know, but it is regarded as considerable. 18. -Q. If it had been perfectly level, how long would it have lasted? A. It ought to have lasted 300 or 400 rounds; and I judge because the average endurance of his guns is 310 rounds. I have always regarded the form of Mr. Parrott's large guns as defective. 19. Q. What damage do you think was done by the guns that did that firing? A. The lower two-thirds of the city, in the first place, was rendered untenable by the batteries playing upon it. I should judge three-fourths of the houses in that portion of the city were to a certain extent injured; sqine of them almost destroyed. 20. Q. Do you think if you had used greater charges of powder in those guns they would 'have been more effective, if they had been able to withstand the pressure? A. They would not have been more effective, so long as we reached the city with the charge we used. The projectiles would have gone a little further, but there would not have been a very great increase in falling. 21. Q. Would they have stood a greater pressure of powder than you did use ? A. They would have stood a greater pressure of pow r der a few rounds, but would not have stood so many rounds. I adopted the plan of using Mr. Parrott's own charge. He prescribed a charge for his gun, and I thought it was but fair to use that charge. 22. Q. Do you know anything of the Ames wrought-iron gun? A. Yes, sir ; something of it. I witnessed the process by which it was made ; and I was president of a board of officers that tested one of Ames's 7-inch rifles in the autumn of 1864. 23. Q. Could you have done any better on the city with one of those guns than you did with Parrott's ? 42 EXPERIMENTS ON HEAVY ORDNANCE. A. If I had had guns all as. good as the one we tried, I could have done better. 24. Q. What sort of a gun was it ? A. This was a wrought : iroii gun, calibre of 7 inches, rifled for a pro- jectile weighing about or over 100 pounds; I forget what it was. 25. Q. Do you know how the velocity of the shot from it compared with that from the Parrott? A. I presume, with the same charges, the initial velocity would be the same. 26. Q. Had it endurance to stand a higher charge of ammunition ? A. I think it had. We used higher charges in testing this gun than Parrott had prescribed for his. 27. Q. How many rounds did that undergo ? A. I believe w^e fired it 713 times, and many of those charges were considerably higher than Parrott uses. 28. Q. Was it fired at greater elevation, too I A. It was fired at greater elevation than the swamp-angel battery. 29. Q. Were the elevations in the trials equal? A. No, sir; but some of the elevations were quite high. Some between 20 and 30 degrees, 1 believe. We fired Parrott's gun as a mortar; I think it was nearly 40 degrees. We fired Mr. Ames's gun several times at high elevation, but it was not as high as that. 30. Q. You got Ames's up to about twice the amount of charges ? A. I think we did; yes, sir. Tke effect upon the gun was to enlarge the bore at the seat of the charge, I think about three-eighths or one- fourth of an inch. That enlargement showed on the outside of the gun in a little bulge all around it. The board reported favorably of that gun, recommended it should be bored out to an 8-inch calibre and tried again. That was subsequently done, I understood, under another board. I had nothing to do with it. 31. Q. Did you see any of those Ames guns afterwards? A. No, sir ; I never had any of them. 32. Q. Did you ever ask for any of them ? A. I had no command after that where I had occasion to use heavy guns. I took command subsequently in the south, but no operations that required heavy guns were going on. 33. Q. Then you could not tell me in how much less time you could have accomplished the chief object on the city with the Ames guns if you had had them in place of Parrott's. A. I did not lay much stress on accomplishing any special object on the city. I could have demolished Fort Sumter sooner if I had had good guns. 34. Q. Suppose you had had the Ames gun there, or something like it a gun you could have relied upon for as much force as you pleased ! A. If I had had a gun that would have stood all the rounds required, I should have saved one-third of the time in demolishing Fort Suniter, for it required a great deal of time in getting up these heavy guns when one of them burst prematurely. 35. Q. I have always had the impression you were very much embar- rassed before Charleston for the want of proper ordnance. How was that, general ? A. We supposed we had the best, though I always supposed a gun ought to stand 1,000 or 1,200 rounds, and Parrott's heavy guns stood on an average 310. 36. Q. We had none but Parrott's when you went there ? A. Never had any heavy guns but Parrott's. We tried to study into EXPERIMENTS ON HEAVY ORDNANCE. 43 the cause of this bursting of guns prematurely. Some officers attributed it to one cause and some to another. Parrott attributed it entirely to the shells bursting inside. I thought it was c^ue mostly to the defective form of the gun in the large guns. I do not want a better small gun than Parrott's. His 30-pounders and 20-pounders have, as a general rule, very great endurance. I suppose after getting a good small gun he was allowed to suppose he could furnish every sort of a gun, and he had such control of the ordnance department that they would take none but his. He applied the same rules in getting out large calibres as with small ones. 37. Q. Suppose you had everything there of the right sort of material when you first made your demonstration on Charleston, what amount of saving of money would there have been ? can you give anything near it? A. If I had had good guns I could have done my share of the work three weeks sooner, I think. After that it was for the navy to go in according to agreement. 38. Q. What would probably have been the saving in life and wounded if you had had guns that would not have burst ? A. We lost no men by the bursting of guns. Do not think we lost a single life by it. 39. Q. Dy you remember how many guns were burst ? A. Including one small gun a 30-pounder I burst 23. 40. Q. In what length of time I A. During the summer and autumn of 1863, and in the winter of 1863->64. 41. Q. How many did you throw out of use besides those actually destroyed ? A. We mounted and used all the guns sent to us as long as they were serviceable. They either became unserviceable by bursting open or by the muzzle blowing off, and we charged them all as bursted guns, making the 23. The 30-pounder which is included in that number was tired at the city of Charleston 4,600 rounds at high elevation. 42. Q. So you think that small guns do better than large ones ? A. Yes, sir ; and other officers who have used them entertain the same opinion. 43. Q. Who took command after you, general ? A. I moved with the tenth army corps to James river and left the command temporarily with General Hatch, and General Foster arrived almost immediately afterwards, and took command. 44. Q. How many Parrott guns burst after that in command of Hatch and Foster ? A. When I went back to the command of the department again in 1865, I found the records of the artillery service in the department and got them together, and I found General Foster had kept up the bom- bardment against Charleston and Sumter, and had burst 27 guns, accord- ing to the report of his chief of artillery. 45. Q. Were any disabled besides those burst ? A. I found no report of any disabled except burst. 46. Q. Were your operations on Charleston any way interfered with by the want of cannon such as you had confidence in f A. Only by the delay which was occasioned by the bursting of the guns in the demolition of Fort Sumter ? 47. Q. That was a great deal, was it not ? A. It would have been a great deal if the programme had been car- ried out, perhaps 5 but the programme was not carried out at all after- wards. 44 EXPERIMENTS ON HEAVY ORDNANCE. 49. Q. I remember the country had an intense interest fixed upon you for a time, and for a while everything was going on finely ; but for some reason it was supposed you were not able to proceed, and I never could understand the cause of it. There was a general impression in the country that you were not supplied properly. A. I was supplied with everything necessary, and I did what I was sent there to do. 50. Q. It was not your instructions to do anything towards the demo- lition of Charleston ? A. I was to demolish Fort Sumter, so it would not be in the way of the navy. The firing on the city was done on my own responsibility. 51. Q. If they had let you alone would not you have taken that city 1 ? A. If they had given me a navy I would have taken it. I had not troops enough to land on the mainland. 52. Q. How many more troops ought you to have had 1 A. In 1863 I ought to have had 10,000 more men to have made my force equal to Beauregard's. 53. Q. That could have been easily supplied? A. The operations in the valley of the Mississippi were pending; then, and all the spare men were going there, to Port Hudson and Vicksburg an(I other points. 54. Q. Could you with the Ames gun, like the one you fired at Bridge- port, have reduced all the enemy's works and the city of Charleston in the time you were there? A. I do not think I can answer that. We did not want any more guns. We wanted a navy. We had guns enough. 55. Q. Give your opinion of the general merits or defects of a heavy wrought-iron gun, as compared with those made of cast iron. A. Well, I have thought from, the experiments at Bridgeport that we had no heavy cast-iron gun as good as Mr. Ames's wrougnt-iron gun. Recent trials with our 15-inch gun have been very satisfactory, and it is possible that gun will be able to do all the ordnance department claim for it. I do not know. 56. Q. If it does that will it be any better than the Ames gun ? A. No, sir, it will not be any better. 57. Q. Do you think it possible to produce uniformity of weld in wrought-iron guns of large calibre? A. I think it is, by Mr. Ames's process, and I think if a defective weld does get into a gun it will be developed in proving it. 58. Q. Give me your opinion generally about the use of wrought-iron guns and their value as compared wilh cast ones. A. A wrought-iron gun, in my opinion, if made by this process of welding rings together, which is Mr. Ames's patent, and we can get a gun without defective welds, would be one of the most valuable guns we could have; and I believe that a defective weld would be developed in proving a gun. If it does not break in the proof charges say eight or ten heavy charges I should regard the welds good. 59. Q. That would be easily tried, then, would it not? A. Yes, sir ; although a defective weld was discovered in the gun we tried at Bridgeport on the second trial. 60. Q. And how long did it last? A. It fired 713 rounds with us, but I believe only fired a few rounds after they bored it out to enlarge the calibre. It was heavy enough for an 8-inch gun, as compared with the weights of guns of that calibre. 61. Q. It burst after having been bored out, did it? A. So I understood. I was not connected with the experiments made EXPERIMENTS ON HEAVY ORDNANCE. 45 afterwards. No piece of cast metal, in my opinion, unless possibly it is cooled on the inside, will make a good gun all in one piece. I do not know but the cooling inside will secure a good gun of very large calibre out of one piece of iron, but I am not satisfied of it entirely; but I do not believe any piece of cast metal, unless it is cooled on the inside, can possibly make a good gun of large calibre. 62. Q. Suppose you had taken Charleston when you first went down there, what would have been tke effect of it on the country! Would not Savannah, Wilmington, and all the other southern ports and places have give up at once? Did not they look on Charleston as the great citadel of the south, on which everything depended? A. They looked upon Charleston as a very important place for block- ade-running. Its military strength never was very great, independent of its being used as a source of supply through blockade-running vessels. Wilmington was equally good. Savannah was used a little through the by-channels. They did not go up the Savannah river, but went up the Wilmington river. I think the effect upon the war would have been to shorten it, though I cannot say how much. I should have regarded Vicksburg as about the the most important capture of any city during the war. But the failure to take Charleston is not intimately connected with the subject of heavy guns. It opens another field entirely. 63. Q. Do you know any gun superior to the Ames gun for strength and endurance? * A. I do not ; but there may be such a gun. My knowledge of heavy guns just now may not be up to the times. I have been on other duty for a year, exclusively. 64. Q. But daring the war you knew all about them? A. Yes, sir ; had a good deal to do with heavy guns up to the time we tried the' Ames gun. Do not think we had anything as good as that, and the board expressed that opinion in their report. 65. Q. You have not heard of any since? A. No, sir. 66. Q. Did the wrought-iron gun enlarge more than the cast-iron or other ones? A. They are apt to. 67. Q. So as to make them materially larger? A. They enlarge considerably more than cast-iron, but they will stand a larger charge without bursting. 68. Q. Then the enlargement is not material, is it? A. Yes, sir; it becomes so after a while. 69. Q. Is there any injury by an enlargement of yL, -i, or 1 of an inch to the calibre? A. There is no injury in the accuracy of the firing, because that enlarge- ment takes place at the seat of the charge, and not along the bore. 70. Q. With the charge used by Mr. Ames in his gun is'it likely to en- large much ; or did those that you saw enlarge much with the use of his ammunition ? A. We did not use Mr. Ames's ammunition. 71. Q. Well, with the ammunition you used, was there much enlarge- ment ? A. The enlargement was not very great until we commenced to use large charges. 72. Q. Is it your opinion that cast-iron rifled cannon can be made to stand sufficient charges of powder to be effective against iron-clad ves- sels or against fortifications that are now being constructed? A. I have not formed any opinion on that subject, and very few officers have, I think. 46 EXPERIMENTS ON HEAVY ORDNANCE. 73. Q. How many times, in your opinion, would the cast-iron 100- pounder rifled gun stand the charge of quick-burning powder, 20 pounds to the charge, and 100-pound shot I A. That is a pretty big charge. How many rounds it would stand is mere guess. I do not know of any cast-iron gun that would stand 500 such charges, and I should be afraid to trust them to stand 200. 74. Q. What is your opinion about the necessity of using rifled cannon I A. If the heavy Rodman guns prove a success, we want very few rifled cannon. If they wiH not stand the heavy charges which the ordnance department expect them to stand, we shall have to resort to rifled cannon to get the necessary velocity and weight of ball to pene- trate iron-clad vessels. 75. Q. That is an experiment yet ? A. Yes, sir. If the 15-inch gun will stand 100 pounds of powder right along through 800 or 900 rounds, we can beat off any iron-clad fleet with those guns, I think. 76. Q. That you do not know yet I A. Only know that they have stood several rounds. 77. Q. Would you think a gun weighing 20,000 pounds capable of pene- trating the same thickness of earth, air, or iron, with 45 pounds of pow- der as a 15-inch gun weighing 49,000 pounds, with 100 pounds of powder, a more desirable gun to obtain for the service ? A. In some respects it would be the most desirable gun 5 in others it would not. 78. Q. It would be a great deal cheaper ? A. It would be cheaper, and a more desirable gun when you wanted to punch a hole through ; but when you wanted the racking effect of a large mass thrown against the side of a vessel, I do not think this small gun would be as good as the big one. 79. Q. Is not that a question with the English authorities, which is the best effect to produce ? A. No $ but it is yet a question with us. 80. Q. Explain your views as to the difference in value of light and heavy guns capable of performing the same amount of work. A. The light guns are the most desirable, if they will do the kind of work you want done, of course. 81. Q. Did you use any smooth-bore guns at all there at Charleston ? A. No, sir $ not large guns. 82. Q. Why? A. All our ranges were very long. I used smooth-bore guns at Fort Pulaski. There we had only a mile to breach, and I did not have any new rifled guns. I had our old 42-pounder and 32-pounder guns rifled out to fit James's projectile ; and then I had the 8-inch and 10-inch smooth-bore columbiad ; but used none of them in our heavy batteries before Charleston, at all. 83. Q. Did not use them as a matter of choice, not because you did not have them ? A. They would not have been effective at the distance I had to fire. 84. Q. What are the charges of powder and shot used in rifled guns above T ^-inch, 7, 8, 9, and 10-inch bore, and do these charges give full velocity to the shot ? A. These charges are given in a table in my report that is, the charges for Parrott rifles. 85. Q. Are you willing that what is said in that report shall go as part of your testimony ? A. Yes, sir ; I am willing to take any or all this book as testimony, EXPERIMENTS ON HEAVY ORDNANCE. 47 ("Engineer and Artillery Operations against the Defences of Charleston Harbor, 1863.") Here are the charges : a 200-pounder is 16 pounds of powder $ a 300-pounder, which is a 10-inch bore, is 25 pounds ; and that is as high as it goes. Parrott has only the 8-inch and 10-inch above the G-^L-inch guns. 86. Q. How much more powder in each calibre would it take to give the shot its greatest velocity ? A. I should think the initial velocity would increase up to one-half more of the charge, though there would be a good deal of unburned powder. 87. Q. Then why is not that largest amount of charge put in so as to give the greatest velocity ? A. The gun would not endure it so long. 88. Q. Then the gun which would endure the more is so much better than one that will not ? A. Yes, sir, certainly ; the heavier charge the gun will endure, the better the gun is. 89. Q. Do you think it a good gun that would not stand such a charge the heaviest amount of charge which its calibre would allow 9 A. It is a mere question of the endurance of iron as against the expan- sive effect of powder. We may not be able to get any gun that will stand the charge you ought to fire to get the greatest velocity, but the gun that will nearest support that is the best. 90. Q. What gun comes the nearest that ? A. I do not know of any gun stronger than Ames's. 91. Q. Then could you tell me what would be the comparative differ- ence between a gun which would stand the largest amount of powder and ball, and one which would take a less amount ? Take, for instance, the Ames and Parrott gun, i i all their usefulness in the service ? A. Well, I should regard the gun that would stand 1,000 rounds as twice as valuable as one that would stand 500 rounds. 92. Q. Would not it be more, because there is all the expense of getting it ready, and loss of time in getting another one ? A. Well, twice as valuable, at least ; unless I made a calculation I could not tell exactly the difference. 93. Q. Are you familiar with the mode of construction of the Ames gun? A. Measurably so ; I saw a portion of the process of making one, and understand how it is made by description 5 it is described in that report of mine. 94. Q. What is the particular value of its construction over a cast-iron or any other one? A. I understand one of the strong points in favor of that mode of con- struction is that the strain upon the metal is brought lengthwise of the fibres to a certain extent. 95. Q. How are the fibres formed ; in parallels, or in transverse sections ? A. The outer ring, if I recollect, is a hoop all around the gun. The inner portion of each ring is a block of iron with a hole punched in it if I do not forget. 96. Q. What advantage is there in that mode of formation ; is that what gives it its power to resist f A. The laminad of the wrought metal lie transversely to the axis of the gun, in the inner portion of each ring. 97. Is not the fibre in iron the result of extension, as candy is drawn out by the confectioner from crystallized sugar ? A. Yes, sir. 48 EXPERIMENTS ON HEAVY ORDNANCE. 98. Q. Does Mr. Ames's system involve initial tension ? A. I should not think it did. 99. Q. Does it give the fibre of the metal a transverse direction around the gun ? A. A portion of the fibre runs round the gun $ a portion of it lies in laminae, transverse to the axis of the gun. 100. Q. Would not the fibre be destroyed by it after heating and a new crystallization be formed ? A. Under continued heating there is a new crystallization to a certain extent, but where it commences and how rapidly it progresses I do not know. 101. Q. If you had sections in the state of tension, deemed necessary to best restrain the pressure from within the gun, would the tension remain after the gun had been heated to the welding temperature 1 A. No 5 it would take off the initial tension. 102. Q. Do you know why the Armstrong gun was fired with enlarg- ing charges previous to the last boring to the final calibre! A. I do not know, though I think I could guess. It was to give the tension. 103. Q. If you were before an enemy, and his guns would stand a third more powder than yours, what would be the value of each ? A. He could reach me before I could him ; that is about it. 104. Q. Could he not destroy you before you could get ready ? A. There would have to be some manoeuvring then, I guess, to get out of his way. However, that problem cannot be figured right down in that way. He would have an advantage on the water, undoubtedly, and the advantage might be measured ; but on the land he would not have that advantage. Probably nearly all the actions on land take place within the range of the weakest ordnance they have. But an enemy on the ocean, having the longest range, can lie at Ms own distance and fight entirely beyond the range of his adversary's guns. 105. Q. Did you notice such uniformity in the manner of bursting guns where accidents have happened under your direct observation as to lead you to think there was a law governing the forces acting to rup- ture them ? A. The force of exploding powder is applied according to a certain law always, of course ? 106. Q. Do you think the pressure of the gas of the powder is uni- form at all times of course, with all the circumstances the same ; is it something that can be calculated definitely with uniformity $ A. The force of the same powder fired under precisely the same cir- cumstances ought to be, and I should think would be, the same. 107. Q. Do you think that, under the most favorable circumstances of lubrication of the shot, smoothness of the bore, and time of ignition of the charge, that the force and velocity imparted to the shot is a fair evolution of the amount of work the powder is capable of performing I A. I do. 108. Q. Then, if any material part of the force of the powder should be expended otherwise than in expelling the shot, for instance, in burst- ing the gun, the shot would not be thrown so far, would it ? A. Shot do go as far at times, about as far, when the gun bursts as when it does not, and the forces are exerted simultaneously on the shot and the gun. This gas, while expelling the ball is also bursting the gun ; the ball gets its velocity in the gun about the same time the gun reaches that strain when it must give way. There is no sudden enlarge- ment of the capacity of the bore behind the ball until the gun gives EXPERIMENTS ON HEAVY ORDNANCE. 49 way. If the gases could expand the capacity of the bore behind the ball suddenly, then the shot would not go as far ; but it does not do that. The gun bursts when the bore enlarges. 109. Q. Would it reach its destined object ? A. It will go just about as far and just about as straight. That is the result of my observation. 110. Q. Then only a portion of the work the powder is capable of doing is exerted on the shot ; the large amount of it being exerted on the gun. A. It is exerted on the shot, too. 111. Q. Do you think a Parrott gun would burst if the shot should be fastened so as not to be moved from its home position ; that is, by the direct pressure of the gas ? A. Well, I do not know. I should think his large guns would ; but I never saw it tried. 112. Q. Would it not be nearly all the work the powder could do to burst the gun under such circumstances ? A. Yes, sir ; I should think it would ; but it will do just as much work towards throwing the projectile at the same time. 113. Q. Do you believe the powder capable of performing twice the amount of work at one time it does at another I A. No ; but I believe it capable of performing work in all directions at the same time. That is the nature of gases, and of fluids too. 114. Q. Then there would be the same amount of force exerted in the chamber of the gun whether the shot went out or not ? A. Yes, sir ; the same amount of force developed. That comes from the nature of gases ; the way gases exert themselves. 115. Q. There have been tables of ranges established for the Parrott gun, I believe ; are they nearly correct ! A. I think so. 116. Q. Have you ever known a shot to perform only one-fourth of its range when all the conditions of loading were attended to properly, and if so, did the gun burst at such time ? A. 'I do not recollect any such case. 117. Q. Then the powder is shown, by the range of the shot, to be nearly uniform in its action I A. Yes. Well, the same powder would be under exactly the same circumstances. I suppose that condition applies to all these questions. The varying character of our powders, the difference in barrels from the same lot, and the difference in portions of the same barrel, introduces all sorts of elements of uncertainty in our firing. But I understand these questions presuppose that the powder is of the same quality, and ignited under the same conditions. 118. Q. The force of the powder being so nearly all expended in eject- ing the shot, there could not be enough of its force spared from the ejec- tion and projection of the shot to burst the gun at the same time and at one operation ; consequently we must assume that the bursting is per- formed a little at a time ? A. If you establish the first part of that question as a hypothesis, I do not exactly understand the condition of things in the bottom of a gun when it is fired to be explained or stated in that question. I think that the work of bursting and ejecting the shot from the gun goes on at the same time, as my other answers indicate. 119. Q. And that when a shot is projected to the extreme extent that it can be thrown, there is just as much force exerted to burst the gun ? A. Certainly the gun is strained just as much. Rep. No. 266 4 50 EXPERIMENTS ON HEAVY OEDNANCE. 120. Q. What change have you noticed in the structure of the iron of guns half an inch from the surface of the bore, which have been fired no more than 300 rounds and then burst, and what in any gun fired more than a thousand rounds I A. I have never examined that very closely, so I have no intelligent answer to give to that. It belongs more especially to fabricating ord- nance. 121. Q. Then you have never known test pieces to be taken from the surface of the bore of a gun that burst ? A. Not under my direction ; it is done, I know, but I am not prepared to give an intelligent answer to that. 122. Q. Do you think a Parrott 100-pounder could be permanently enlarged in its calibre by bursting five shells at a time in the bore ? A. Simultaneously I 123. Q. Yes, at one explosion. A. No, 1 do not believe it would 5 not if there was no charge behind. If there was a charge behind and wedging should take place, there might be a permanent enlargement. I do not believe to explode the charges in the shells would burst the gun. It might, though I should not think it would. 124. Q. Then your theory is that w^hen the shell bursts in the gun, if the gun bursts it is occasioned by the wedging of the shell. A. Yes ; the gun may be weakened by being deeply scratched by frag- ments of the shells, but the great strain on the gun when the shell bursts in it comes from wedging. 125. Q. Do you think a Parrott 100-pounder could be broken in two just forward of the reinforce band by a fair blow from the shot of another gun of the same kind ; or would it require a number of shots to break it? A. I should think it might be broken or injured so that it would not be fit for any service. It might be indented so as to reach clear through into the bore. 126. Q. Have you an idea as to the depth of the indentation I A. I think the gun might be permanently disabled by even one shot fired against it at the chase. It might require more than one. 127. Q. Have you ever seen an indentation in the surface of the bore of a Parrott gun which has burst, from which you could determine whether the force with which the bursting shell had acted on the bore had been sufficient to cause the rupture? A. No, I never regarded the bursting of shells sufficient to burst Par- rott guns. I have seen the effect on the bore of shells bursting in the gun, but I never regarded it sufficiently serious to cause the bursting of the gun unless repeated a great many times. 128. Q. Do you think the Parrott guns would burst if cast on the Eod- man plan ? A. I have always entertained the belief that they would be better if cast on that plan, and I understood he did cast his guns, latterly, on that plan. Indeed, I understood it was a condition imposed by the depart- ment that he should cast them in that way, but I may be mistaken. 129. Q. Is it your opinion that would prevent their bursting I A. I do not know. I think it would improve them, give them greater endurance. 130. Q. Will you explain the advantage which the Bodman plan gives in enabling a gun to resist the direct pressure of the powder ? A. It puts the metal in that condition to bring its strength throughout the entire thickness of the gun into play when it is fired 5 a portion of it being under initial compression in the start. EXPERIMENTS ON HEAVY ORDNANCE. 51 131. Q. Would a Rodman gun cast hollow and cooled from the interior, or a solid cast gun of the same iron, model, and weight, be best able to resist the breaking by unequal expansion, if a heated rod of iron should be inserted in the bore ? A. I should think the gun cast solid and bored out would stand the introduction of the red-hot rod best. 132. Q. This tension would weaken the gun for resisting the expand- ing force ? A. I think so. 133. Would it be possible, in your opinion, to shrink the band on the Parrott gun with force enough to reduce the diameter of the bore 1 A. I should not think it would be, but I have been told by those engaged in making the guns that it actually takes place. . 134. Q. Could the length of the bore be increased in any slight degree by the shrinking of the band ? A. I should think not. 135. Q. If the gun were made of India-rubber, and th e band were shrunk on, would it increase the length of the gun ? A. I think there is some doubt about whether it would. India-rubber undergoes compression. I do not think it would necessarily increase the length to compress it. It might a little. India-rubber is not much like cast-iron, though India-rubber can be compressed without its dimensions in a lateral direction undergoing any change. I should think in the case of a tube, though violently compressed that way by a band shrinking on it, it would elongate a little. 136. Q. If the band was so placed on the gun as to reduce the diam- eter slightly, and if it should increase the length slightly also, and the gun should then heat from the interior, would not the band be probably strong enough to prevent radial expansion, and cause the interior of the metal to flow towards the breech, and towards the muzzle under the band? A. Yes; that would be the tendency. 136. Q. If the cast iron beneath the band were hottest within the bore, and had a gradually reduced temperature towards the outside, would not the expansion of the inner metal lengthwise have a tendency to break the outside, which would not expand so much ? A. That is the tendency. 137. Q. Dp you not believe that it is easier to restrain the expansion of a gun radially if you permit it to expand longitudinally? A. Yes. 138. Q. Dp you think it would be possible to restrain the expansion of the cast iron of a Parrott gun in all directions by any plan of an adjusting band? A. No ; nor any other gun. That does not apply to Parrottfs especially. 139. Q. If you doubted that the transverse fracture of the Parrott gun was caused by the unequal heating alone, would you believe the heat might cause tensions which would assist the force of the powder to break the gun ? A. Heat develops forces which would tend to break a gun. It is the very first tendency for a gun to break in two when fired. 140. Q. If a strong current of hot gases should be brushing over or across the surface of metal, do you think more heat would be communi- cated to the same area of surface than would be if the heated gas were merely pressing against the surface without currents for the same time of exposure ? A. I do not know, I am sure. 52 EXPERIMENTS ON HEAVY ORDNANCE. 141. Q. Is not the surface of the vent liable to receive more heat per square inch on its surface according to the strength of the current, and the length of time the current plays over it, than any other equal surface of the bore of the gun ? A. It is subject to greater wear. Whether a greater degree of heat is evolved there I do not know. 142. Q. If the metal surrounding the vent for a radius of two inches should be heated in this manner, a force would be exerted similar to that which would be exerted if a hole four inches in diameter were made in the gun with its axis coinciding with the axis of the vent, and a slightly tapered bolt driven into it, would not the gun be liable to break trans- versely at that point when the force of the powder came to act upon it ? A. That would be the tendency. By the CHAIRMAN pro tern. : 143. Q. Do you know whose 12-inch rifle projectiles were used against the iron targets at Fortress Monroe on September 21 and 22, last year ? A. They were called the Dyer projectile, with the Taylor sabot. That is what we were informed down there. I was on the board. That is what Colonel Baylor told me ; and Mr. Taylor was there to superintend their use. 144. Q. You saw him there on the experimental grounds ? A. Yes, sir; I understood from officers there the original sabot of General Dyer had been improved upon by Mr. Taylor in its form and in the composition. 145. Q. Did he explain to you the composition of the sabot he used in the 12-inch projectiles ? A. He explained the way it was attached ; and I remember I took a memorandum of the different component parts of the composition. There were copper, tin, and lead in it, and he gave me the proportions at the time, I think, but I do not recollect what they were. 146. Q. Did the sabot metal take the grooves well? A. Yery well, indeed. 147. Q. And did the firing exhibit accuracy? A. Yes, sir. 148. Q. Can you give any opinion as to the value of the sabot com- posed of that metal as compared with other kinds of sabots you have seen? A. I have no opinion with regard to the advantage of that peculiar kind of alloy composition, though I know these projectiles worked as well as if not better than any I ever saw used, and I presumed at the time it was in consequence of having a very good sabot on. 149. Q. Will you look at the two diagrams, accompanying the patent of Taylor's soft-metal sabot, and tell me whether the sabots which were used with the projectiles at these experiments were figure 1 and figure 2.? A. Figure 1 is a drawing representing what I suppose to be a Dyer projectile, with the Taylor sabot on, or resembles the kind of projectiles used in the experimental firing at Old Point Comfort in September, 1866. The ordnance officers there informed me it was the Dyer projectile with the Taylor sabot. The firing was accurate and satisfactory. Colonel Baylor was the officer with whom I had the conversation. 150. Q. What advantage or disadvantage do you think there is in having guns of different calibres with different ammunition for the army and navy ? A. It is a disadvantage, I think. 151. Q. Would there not be a very great simplifying of the arming of EXPERIMENTS ON HEAVY ORDNANCE. 53 the two arms of the service, and a very great mutual advantage, if it were possible to use alternately the same guns and the same ammunition in the army and in the navy ? A. It would be better. I had occasion to borrow guns of the navy on Morris Island. They happened to have the guns I wanted, and suited the ammunition I had ; and it was a very great convenience. They were Parrott guns. It would be an advantage if all the calibres corresponded in the two arms of the service. 152. Q. Do you know of any other cases within your experience where there might have been an interchange of arms or ammunition if the cali- bres had been the same in the army and navy ? A. Cases of that kind would only occur in joint expeditions like the one I was connected with. I do not recollect any other case. Extract from testimony of Brigadier General A. B. Dyer. JANUARY 18, 1868. By Mr. BUTLER : ###*### 1. Question. What is the amount that is paid, either in percentage or in gross, as you may remember, to General Eodman ? Answer. I do not know that anything has been paid. I have no knowledge of any amount having been paid. 2. Q. As a royalty on his gun ? A. None at all. I have answered that question in writing as fully as I could. 3. Q. That may be, sir. A. I have no knowledge whatever of the matter. 4. Q. Have you any knowledge whatever that the price of guns of the Eodman pattern has in any way been increased because of his royalty, or because of any sums to be paid on account of his patent, directly or indirectly? A. I have understood that there was a royalty entering into the price of the gun. 5. Q. How many hundred thousand dollars' worth, within bounds, have you ordered of the Eodman gun since you have been Chief of Ordnance? A. I do not remember. 6. Q. Many hundred thousands? A. Yes. 7. Q. Amounting to millions? A. I do not know whether amounting to millions or not. 8. Q. Do you mean to say that in ordering many hundred thousand pounds, amounting to millions, perhaps, of the Eodman gun, you never inquired as to whether the price was increased by a royalty or not? A. I knew that the price was increased by a royalty. 9. Q. Did you not inquire how much? A. I had seen it in print in the testimony taken before the Com- mittee on the Conduct of the War. The price was one cent per pound. 10. Q. Did not you inquire otherwise than what you saw in print? A. No, I am not aware that I ever did. 11. Q. Then, in contracting for many hundred thousand dollars' worth of ordnance, you made no inquiry except what you saw in the printed testimony taken by the Committee on the Conduct of the War as to whether the price was increased by a royalty paid to an officer of the ordinance department ? 54 EXPERIMENTS ON HEAVY ORDNANCE. A. I never knew that this was paid to an officer of the department. 12. Q. Or because of a patent given an officer of the department ? A. I had understood this, and I did not make any further inquiries; had understood several years ago that this entered into and constituted a part of the cost. 13. Q. What proportion of the cost of a piece of heavy ordnance would one cent per pound be as an average? A. Something like one-twelfth, I suppose. 14. Q. What have you paid a pound, on an average, for the Hodman guns? Give me the extreme limits, the lowest and the highest, since April, 1861. A. I should have to refer to my report, which will probably show. 15. Q. Can you give me approximately the limits ? A. No ; I do not remember what w^as paid in the early part of the war for them. I can tell you the later prices that have been paid. 16. Q. In the early part of the war as low as six or eight cents? A. Yes, I think probably in the early part of the war as low as six or eight cents. 17. Q. Now paid ? A. I think about twelve cents. 18. Q. Then it would vary from one-sixth to one-twelfth I A. If it had been as low as six and as high as twelve yes, I should think so. 19. Q. Did you understand that this royalty or patent had been pur- chased by Mr. Knap ? A. I did. . 20. Q. Did he make all the Rodman guns I A. He did not. 21. Q. Who did? A. They were made by Mr. Knap; by the South Boston foundry, (Alger & Co. ; ) by the Eeading (Pa.) foundry, (Seyfort, McManus & Co.; ) and by Mr. Parrott. 22. Q. Were not all those guns increased in price by the royalty? A. I have no doubt of it, sir. 23. Q, And the makers had all to pay this royalty, which they added to the other cost of the gun? A. I know nothing whatever of that. 24. Q. Do you know of any arrangement by which they did not have to pay it? A. I know neither one thing nor the other in regard to that. 25. Q. I find from your report that the amount paid for Rodman guns is $2,636,600, up to June 30, 1866 ? A. Yes, sir. 26. Q. Did not you know Mr. Rodman was interested one-half in that royalty ? A. I had no other knowledge than from hearsay j I believed it. 27. Q. That he had one-half? A. I believed he had one-half. 28. Q. Estimating the royalty at an average of one-tenth the cost, the whole amount of royalty paid on those guns would be $263,660. That was so, was it not? A. You made the calculation ? 29. Q. Will you not see if I am right ? A. I believe so. 30. Q. This is up to June 30, 1866. How many of those guns have been purchased since? EXPERIMENTS ON HEAVY ORDNANCE. 55 A. I do not remember, sir. 31. Q. Are they still being purchased? A. They are not. 32. Q. When did it cease? A. I think no orders have been given. 33. Q. When did they cease being purchased? Giving orders might be one thing, and purchasing another. They might be received in ful- filment of old orders ? A. I think the last deliveries were made somewhere about a year ago a little more or a little less a little less, I think. 34. Q. I find in the last report of the Secretary of War the following : A board of engineer, ordnance, and artillery officers, specially appointed to consider this the calibre of 13, 15, A board ot engineer, ordnance, and artillery officers, specially appoi subject of arming the permanent forts, reported the 1,915 pieces of th and 20 inches for smooth-bores, and of 10 and 12 inches for rifles, were required for the per- manent fortifications, and should be provided, and their report was approved by the Secre- tary of War. None of these guns have yet been provided. There are no orders or contracts existing for heavy cannon. This stoppage of the procurement of heavy cannon has been mainly occasioned by "persistent efforts for some time past by ignorant or designing persons to destroy public confidence in the heavy guns which have been provided for the ordnance departments of the army and navy." This*language, "persistent efforts for some time past by ignorant or designing persons to destroy public confidence in the heavy guns which have been provided for the ordnance departments of the army and navy," is quoted by the Secretary of War from the report of the Chief of Ord- nance? A. Yes. 35. Q. To whom, sir, did you refer in that report? A. I referred to the articles which were published in the newspapers, as I state, from time to time. I should like to read that portion of my report. 36. Q. We have not been able to get a copy. That is taken from your report, is it not? A. That is from my report. 37. Q. When you say, in your report, "persistent efforts" have been made u for some time past by ignorant or designing persons to destroy public confidence in the heavy guns which have been provided for the ordnance departments of the army and navy," you refer to articles which appeared in the newspapers? A. Yes, sir; and to specimens of iron castings which are exposed here in the old hall of representatives. 38. Q. To anything else? A. I am not aware that I referred to anything else ; do not remember that I did ; but those I mainly referred to. 39. Q. Did you stop the business of the ordnance department in arm- ing the fortifications because of articles in newspapers, and because of the exposure of the iron castings in the old hall of representatives in the Capitol? A. I did not stop on that account at all. The engineers, or the chief engineer, asked for certain heavy guns about a year or more ago. Some of those guns were guns which had not been adopted, were not of the models that had been adopted for the arming of the forts, and I, upon consulting with him, asked that a board of officers might be appointed engineer, artillery, and ordnance officers for the purpose of considering the question of the armament of the forts and determining what guns were required ; and I stopped procuring guns, or declined to give any orders for guns, until this board had reported and their report had been approved by the Secretary of War and the guns ordered. 56 EXPERIMENTS ON HEAVY ORDNANCE. 40. Q. Is that the "board of engineer, ordnance, and artillery officers specially appointed to consider the subject," referred to here? A. That is the board referred to there. 41. Q. Do I now understand you to say you did not stop until a board was ordered and they had recommended, and their recommendation had been approved by the Secretary of War? Hew do you explain, then, that immediately following you say: "This stoppage of the procurement of heavy cannon has been mainly occasioned by i persistent efforts for some time past by ignorant or designing persons to destroy public con- fidence in the heavy guns which have been provided for the ordnance . departments of the army and navy?'" A. "This stoppage of the procurement ; n I am not aware that I said that. 42. Q. "By persistent efforts?" A. I am not aware that I ever said it. 43. Q. Have you received your report in print? A. Yes, sir. 44. Q. I pass from this, then, till I can get your report. # # * * '# * * 45. Q. To return, now, to this question of heavy ordnance : Is there any authority for saying that the arming of the forts has been stopped mainly because of these publications in the newspapers and the exhibi- tion of these castings in the old house chamber? A. I am not aware that I have said it. 46. Q. That is not the question whether you have said it. The question is, whether it is a fact? A. No. I do not know that it is a fact. 47. Q. Then there is no authority for saying that? A. May I ask whether you supposed I had said so? 48. Q. I supposed so for this reason A. That does not appear to be in quotation marks, and what purports to come from my report. 49. Q. I want to ascertain if it is truje, being said by anybody else ; because it is put forward that ignorant and designing persons have stopped the arming of the forts; and, if it is true, it is time those persons got out of the way and the armament of the forts went on. Somebody said it, evidently ; and the statement is sent to us for our information by Congress. Now, I think it is fair for you to say that you have not said it. I have now here your report ; all you have said is this : Persistent efforts have been made, for some time past, by ignorant and designing persons, to destroy public confidence in the heavy guns which have been provided for the ordnance departments of the army and navy. Iron castings, placarded as representing the condition of the metal in our heavy guns, have been placed in conspicuous public places, and publications have appeared from time to time, in prominent journals, asserting that these guns were worthless, that they could only be fired with very light charges of powder, and that they would burst if fired a few- times rapidly. But you nowhere say here that you have stopped on that account ? A. I told you I was not aware of saying it. 50. Q. At any rate, you are certain you never did? A. I am not aware that I ever did on that account. I do not know what the Secretary of War may have done. 51. Q. He could not have done anything of that sort without your knowledge without its coming through you? A. He gave me an order, last spring, to procure no more heavy guns without his further authority. EXPERIMENTS ON HEAVY ORDNANCE. 57 52. Q. Did you understand that order to be in consequence of a reso- lution from this committee 1 ? A. I believe that it was in consequence of it. Extract from the statement of General Dyer, February 5, 1868 : It is true, as stated by Mr. Wall in his testimony, that some Rodman guns have been accepted and paid for before being fired ; but no gun has been accepted and paid for which did not fulfil all the conditions required by the contract, and it is confidently believed that no better guns have been furnished the government than are all of the heavy guns which have been procured since I came into the bureau. The ordnance department, through its constructor of ordnance, determines the kind of metal which shall be used, and fixes the limits of tenacity, density, and initial strain, and the character of the fracture of the metal. Specimens have been taken from every gun, and no gun has been accepted the metal of which had not been prouounce^by the constructor of ordnance to be entirely satisfactory. It is believed that a larger proportion of guns have been condemned under the rigid system of tests which have been established by the depart- ment than were formerly condemned when the guns were subjected to a severe powder proof. To the best of my recollection and belief every Rodman gun made for the ordnance depart- ment at the Fort Pitt foundry, Reading foundry, and the West Point foundry, has been fired three times at the foundries, and not one has failed under the powder proof. As there was no suitable proving ground at South Boston foundry, the 15-inch Rodman guns which were made there, and which are known to be equal to the very best guns of the kind which have been made, were not subjected to powder proof at the foundry, nor was it considered neces- sary ; and as the founder was held responsible for the quality of the metal, as determined by tests prescribed by the department for the soundness of casting and for the correctness of the dimensions of the finished gun, and not for the result of the tiring, the tiring was deferred until the guns should be mounted in the forts. Not one 15-inch army gun has ever burst, and some of them have been fired with twice the quantity prescribed for the proof of such guns. Oue gun, taken without selection from those made at South Boston foundry, and not before proved by firing, has been fired more than 250 times, upwards of 130 rounds being with 100 pounds of powder and solid shot. I never directed Mr. J. C. Wall not to prepare copies of the inspection reports of cannon for j'our committee. I always intended to furnish them, and, as far as I could, all other iuformation which was called for by the committee, as is well' known to General Maynadier, Colonel Tread well, and Major McGinness, officers on duty in the bureau, and to Mr. Keller, Mr. McNally, Mr. Williams, and the other clerks in the bureau, who have been employed under their direction in preparing the information called for by the committee. I am very confident that all of these gentlemen will testify that my instructions have been to prepare full, complete, and true answers to all the questions asked by the committee. WASHINGTON, D. C., January 25, 1868. Professor, E. "N. HORSFORD, of Cambridge, Massachusetts, sworn and examined : By Mr. BUTLER : 1. Q. What is your profession or business occupation? A. I have been a professor in Harvard College, until within two or three years, for the previous sixteen years. 2. Q. Have you had such experience as would lead you to have a knowledge of gunpowder and its effects on iron ? A. I have made some experiments with a view of determining the tena- city of iron when subjected to the pressure of burning gunpowder. Shall I go on to state the experiments? 3. Q. You may do so briefly. A. I prepared short barrels by cutting off sections of Sharpens rifle barrels, and fitted them with screw-thread plugs at each end of these short barrels, as a preparatory step to my experiments. The plugs were fitted as male screws, with counter-sunk shoulders, so that with the aid of a wrench and vice I could bring the plugs home to the face of the end of the barrel, there being an inch in length of the interior of my short cylinder for gunpowder. In one of the cylinders I placed (the cavity 58 EXPERIMENTS ON HEAVY ORDNANCE. being an inch in length) half an inch of loose rifle powder ; that is, half filled the cavity. In another I quite filled the cavity. In a third I pat in gunpowder compressed in the cylinder, two volumes in one. When all the plugs were driven home, I threw the three cylinders into the fire. After an interval of a few minutes, one of the cylinders gave a report ; and a little later, another gave a report ; and there was no further report that is, one of them did not give any report. I took these cylinders from the factory to my laboratory, took out the plugs and found only sulphide of iron (a compound of sulphur and iron) coating the interior of each cylinder up to the point where the plug and the cylinder fitted to each other. From that point, out along the line of the screw-thread, there was in every case a channel, making the screw-thread thereafter fit loosely. The surface of this channel (it being understood that the male and female screws originally fitted with very great precision) was coated with a compound of sulphur and iron. I found this to be true in all of the cases, the channel deeper (more of the metal having been removed) in the case of the compressed gunpowder than in the case of either of the other two. I repeated these experiments in my laboratory, suspend- ing the cylinder immediately after the explosion in water. Under such circumstances, the surface of the cylinder was immediately coated with myriads of minute bubbles. I then suspended the same cylinder, after another experiment, in a solution of lime water, and found that, from each of these points where the bubbles had before appeared, a stream of fine white powder descended to the bottom of the vessel containing the lime water. This was proof that carbonic acid came from the pores of the metal. I found the exterior surface of the iron also to contain sulphur in combination with the iron. I found in an experiment with a piece of firing apparatus, devised by Professor Treadwell, where gunpowder was exploded under pressure, that the sulphur came through the iron and appeared at the surface, as in my experiments with the short barrels. From these experiments, as well as from the fact, familiar to all artil- lerists, that the vent of a cannon constantly increases in diameter under firing, I drew the conclusion that the sulphur of the gunpowder under pressure and under the influence of heat, in a degree leaves the saltpetre and the charcoal of the gunpowder, and enters into combination with the iron, forming a compound at the surface of the iron eminently fusible, which, in the current of gases escaping through the vent-hole, or wher- ever there is a current of gas at the instant of the combination of the sulphur with the iron, strips this molten sulphide of iron off, enlarging the vent. 4. Q. Did these various experiments which you have described lead you to an opinion as to the cause of the burning out of the iron in the bottom of the bore of cannon, as well as at the vent? A. It led me to form an opinion as to the cause of the cavity which has been described to me as having been formed in some wrought-iron guns which have been subjected to experiment within the last three or four years guns made by Mr. Ames. o. Q. Was the cause of the formation of that cavity the same as of the enlargement of the vent of the guns? A. It is well known that if gunpowder be subjected to heat under pressure even without pressure the sulphur may be all distilled from the saltpetre and the charcoal, leaving the saltpetre and charcoal quite pure. I conceive that under pressure, in the experiments which I made, the sulphur was distilled in part without entering into combination to form sulphuric or sulphurous acids. In the case of the cannon, to which the question refers, I conceive, as a resultant of the forces brought into EXPERIMENTS ON HEAVY ORDNANCE. 59 play, there would be, at the instant of the explosion of the cartridge, along the axis of the gun and towards the cascable, something like a jet of gaseous sulphur, which, striking the metal, would act to accomplish the same effect that is produced in the vent; that is, a stream of sulphur vapor, playing upon a surface of iron, forms a compound the instant the sulphur strikes the metal ; which compound, being fusible at a low tem- perature, is stripped from the surface as fast as formed, and so long as the stream is kept up. This jet would excavate a hole in the direction of the axis. This action would be more 'energetic at the commencement of the explosion of the gunpowder than after the ball has left its seat at any rate, after some considerable expansion of the products of com- bustion has taken place. 6. Q. Would increasing the pressure of the powder increase its effect in producing this result? A. The increase in pressure, retarding the escape, and so keeping the sulphur there longer, to produce its effect, would accomplish that end. 7. Q. What is the difference in the bursting strain on a cannon charged with powder giving a pressure, say, of 87,000 pounds to the inch, and of powder giving but 35,000 pounds, pressure ? A. The ratio is as the square. If 35 gave you a pressure of 1, 70 would give you a pressure of 4 ; 87 would be somewhere about 5. 8. Q. So the pressure in the first case, with powder exerting a pressure of 87,000 pounds to the inch, would be about five times as great, you say, as of powder with a pressure of 35,000 pounds ? A. Yes, sir ; about that. 9. Q. Having two guns of equal calibre, firing equal weights of powder, one of them being observed to be excavated at the bottom of the bore, in form of a comparatively slender tube or cylinder a long irregular cylin- drical cavity to what should that difference in the effect be ascribed? A. To the greater strength of the gunpowder, inasmuch as a more powerful jet of sulphur would be brought to play upon the bottom of the chamber in the line of the axis than would be with a powder of less strength. WASHINGTON, D. C., February 20, 1868. ISAAC FRENCH sworn and examined. By the CHAIRMAN : 1. Q. Please give your name in full? A. Isaac French. 2. Q. Give your age, residence, and occupation ? A. I am 53 years of age ; I reside in Salisbury, Connecticut, and I am a blacksmith or hammerman by trade. 3. Q. Are you familiar with the working of iron? A. I am. 4. Q. How long have you been engaged in that business ? A. Nearly 40 years. 5. Q. Do vou know Mr. Horatio Ames ? A. I do. 6. Q. Have you been in his employ at any time? A. I have worked for him about 30 years. 7. Q. In what capacity ? A. As a blacksmith, hammerman, or heater, and other things. 8. Q. Were you in his employ at the time he made the 11 100-pounder guns for the government ? 60 EXPERIMENTS ON HEAVY ORDNANCE. A. I was. 9. Q. Were those guns made under your immediate personal inspec- tion If A. Yes. 10. Q. During all the different stages of their manufacture f A. Yes ; I did a good share of the work myself. It was all done under my notice. 11. Q. Will you state briefly the manner in which the guns were manu- factured, beginning with the mode of making each ring, and then the putting the rings together and forming the gun ? A. In the first place the iron is puddled ; that is, put into a furnace and melted, and then it is stirred and worked in a manner similar to the churning of butter, until it finally can be gathered into a ball, when it is taken out in the form of a large ball and put under a hammer and beaten into plates about four or five inches wide and 18 inches long. Then we put three or four of them together and draw them out into a bar about five and a half inches wide and three to three and a half feet long. Then we cut these into three pieces and pile one piece upon the top of the other. Then we draw them out into what we call a slot, about two feet and a half long and eight inches wide. Then we take them to the hammer, and pile them up on what we call a porter-bar, when they are heated and drawn out into bars for rings, six inches square. That is one kind of ring. There are three or four different kinds. But that is the process and way of working the iron. Then the ends are cut off, and they are put into a furnace and heated and bent around into a ring. They are then taken to a blacksmith's fire and welded together ; then to the machine shop, and the inside is bored out to ten inches in diameter and so as to leave them perfectly smooth on the inside. The face is also turned off smooth. That is the process of making the middle ring of the cylinder of the gun. The iron for the inside ring is made in the same way and put together in the same way, only the ring is larger, being drawn 8 by 10 inches. Then they are slotted off and a hole four inches in diameter is bored through them. They are then put on a mandrel or arbor and turned off so as to be 10 inches in diameter. Then they are nicely fitted into this other ring that I have described. For the cylinder of the gun we have another ring still, outside of this, six inches by three. That is shrunk on to the other two. That forms the rings 5 and that is all I can say about that. There were three rings thus, one inside of the other. The middle ring, which is ten inches in diameter, projects about five-eighths of an inch from the other on the side that goes on to the gun. The object of the projection is to have it strike in the centre of the weld, the centre of the gun, first. We have what we call a porter bar, and on the end of this porter bar we form a lump for the breech, about 15 inches in diameter. Then we weld a ring around that, nine inches by three and a half, and another we have a horizontal hammer, by which we upset this and make it square ring around that, three by six. That forms the breech of the gun. Then on the end, or a little oval. Then that is heated in one furnace and the ring in another. Then we fetch the gun out of one of the furnaces by this porter bar, and place it in a large groove, under a big steam hammer. We fetch the ring out of another furnace with a large pair of tongs and place it right against the end of the gun. Then this horizontal hammer which I have spoken of strikes against it and butts it up to weld it on. There is a blocking behind the porter-bar that holds it fast, and keeps it from going back. Thus we keep putting on rings until the gun is long EXPERIMENTS ON HEAVY ORDNANCE. 61 enough ; but when we get past the cylinder of the gun we have only two rings. 12. Q. The strength of the gun depends upon the perfection of the welds ? A. Yes, of course. 13. Q. From your experience in making these guns, is it your opinion that, with proper care you can produce reliable and perfect welds I A. Yes, we can, just as well as in any other way in the world. 14. Q. When the weld is properly made, is perfect, is there any weak- ness at the welding point ? A. I do not see why there should be any more than at any other part of the gun. 15. Q. Is it as strong there as at any other portion of the gun? A. I do not see why it is not. 16. Q. Did you have any failure to make the welds, during your expe- rience ? A. No, not on the guns that I made. 17. Q. Did Mr. Anies, in making any guns, fail in making a weld at any time ? A. We tried various experiments, and sometimes the welds were not perfect. 18. Q. But after the system was perfected you think the welds were such as could be depended upon ? A. I think the eleven guns were perfect welds, and were as solid there as any where. 19. Q. And you say you saw those guns during every step in their manufacture, so that you have perfect knowledge of them? A. Yes ; I saw the iron from the pig until they were finished. 20. Q. Are you confident there was no defect, owing to carelessness ? A. I took every pains possible, and saw every ring put on. 21. Q. What was the character of the iron used ? A. I think it was the best iron I have ever worked Salisbury iron ; I never worked any that would stand the heat as well. 22. Q. Is it superior in certain qualities ? A. Yes; some iron when a little over-heated has its welding power destroyed. But the Salisbury iron is not so 5 and if hammered a little it can be brought back to its original nature. 23. Q. Have you any personal interest in this claim of Mr. Ames? A. I have not any more than my daily wages. I have worked 30 years for Mr. Ames, and he has never given me any bribes. 24. Q. Then you have not now any interest in it ? A. No, only if he makes guns and I work for him, he will pay me. WASHINGTON, D. C., February 20, 1868. Mr. JAMES WILSON sworn and examined. By the CHAIRMAN : 1. Q. Please give your name and residence. A. My name is James Wilson; I reside in Washington. 2. Q. What is your occupation ? A. Foreman and forger, at present, at the Washington navy yard. 3. Q. Do you know anything about these wrought-iron guns which Mr. Ames made for the Navy Department ? A. No. 62 EXPERIMENTS ON HEAVY ORDNANCE. 4. Q. Have you ever seen them made? A. No. 5. Q. Are welds, when perfectly made, as strong as any other part of the iron f A. Yes ; I think they are quite as strong. 6. Q. What is your opinion about the possibility of making perfect welds in large masses of iron, if you have suitable tools and furnaces ? A. I think you can do it and make them perfect. 7. Q. You have heard the system of manufacture described here of Mr. Ames's guns ? A. Yes. 8. Q. Will you state if you have any doubt that the welds could be made perfectly by that system ? A. I have no doubt in the world ; I believe it can be done. 9. Q. Then you think there is no reason why large masses of iron should oxidize so as to prevent welding, if only skilfully and properly manipulated ? A. None in the world. 10. Q. Will not large masses of certain iron be longer in oxidizing than smaller quantities, owing to the greater amount of the heat ? A. No ; I do not think they would. 11. Q. Do you think that would be in proportion to the surface pre- sented 1 A. Yes, I do not see any difference in that respect between a large and a small piece. WASHINGTON, D. 0., February 20, 1868. WILLIAM W. BRADLEY sworn and examined. By the CHAIRMAN : 1. Q. Please give your name, residence and occupation. A. My name is William W. Bradley ; I reside in Washington, I am at the present time clerk in the ordnance department ; I am a machinist by trade. 2. Q. Did you in the summer of 1865, by direction of the ordnance department, carry to Mr. Horatio Ames drawings for the rilling of two guns ? A. I went by the direction of the ordnance department, but I do not think I took the drawings ; I think Mr. Thomas, Mr. Ames's foreman, took them. 3. Q. Will you describe the drawings I How many different kinds of rifled guns were there ? A. Two. 4. Q. What were they ? A. One with the ordinary square rifling 5 the other was one of Brooks's rifling. 5. Q. How long wer you at Mr. Ames's works ? A. I got there on the 6th of July, and I left, I think, on the first of August. 6. Q. Did you have opportunities of observing the manufacture of guns ? A. I did, perfectly ; I took a great interest in it, and saw everything. 7. Q. What was your opinion of the value of that system, for making strong guns? EXPERIMENTS ON HEAVY ORDNANCE. 63 A. I think it was a most admirable system, the best I ever saw ; that if iron cannot be put together by that system, there is none by which it can. 8. Q. The whole question is whether welds could be made perfectly by that system. Do you think they could ? A. Yes, I think the plan of presenting the convex surfaces is the true one, and that thus all the scoriae is forced out by the horizontal hammer. 9. Q. Were you in the battle of Fort Fisher ? A. I was. 10. Q. Did any guns burst there to your knowledge, on board our fleet ? A. Yes, but not on the vessel on which I was, but on some in the vicinity. 11. Q. Did you understand^ that after guns burst the charges were reduced ? A. I think the order was to reduce to eight pounds, the vessel to which I was attached had a 100-pouiider, but it was taken and laid aside and never fired after. 12. Q. Was it the opinion that the excessive charging was the cause of the bursting ? A. There were many opinions expressed; some had one and some another 5 I had my own opinion. Some thought it was on account of the construction of the gun, and some that it was owing to excessive charging. 13; Q. Was the efficiency of the guns reduced by lessening the charge ? A. The efficiency, of course, depends upon the power behind the pro- ectile j if you diminish the power you diminish the efficiency, of course. 14. Q. What was the efficiency of these guns with the eight-pound charge f A. I never saw any experiment with an eight-pound charge ; but my own experience would demonstrate that if it would take a lull charge to keep the shot or shell point on, and not have a rotary motion, by dimin- ishing it, it would not go point on, but would have a tendency to turn oft'. ' 15. Q. Did you see any of those guns after they were burst? A. Only small fragments of the gun on board the Ticonderoga. 16. Q. What was your view of the cause of their bursting? A. I think the guns were improperly made. 17. Q. How? A. I do not think cast iron is capable of bearing such an immense strain. The strain being brought on the cast iron the hoop is all that holds it. WASHINGTON, D. C., January^ 25, 1869. Brevet Brigadier General T. J. KODMAN sworn and examined. By the CHAIRMAN : 1. Q. Have you in any way the superintendence of the construction of ordnance in the War Department 1 A. I am constructor of ordnance of the ordnance department. 2. Q. Are you the inventor of what is known in the ordnance depart- ment as the Rodman system of fabricating cannon ? A. Yes. 64 EXPERIMENTS ON HEAVY ORDNANCE. 3. Q. At what time did you originate this system? A. In 1845, I first commenced it. 4. Q. When was it adopted by the War Department ? A. I think it can be said to have been first adopted in 1862. 5. Q. When by the navy I A. I do not know that it has been adopted by the Navy Department, except for 12-inch rifles, 15-inch or larger smooth-bore guns. 6. Q. At what foundries have guns been made upon your system ? A. The first guns were made at the Fort Pitt foundry. They were then made at South Boston, 0. Alger & Co. ; at the Scott foundry, Bead- ing, Pa., Seyfort, McManus & Co.; and at Mr. Parrott's, Cold 'Spring, N. Y. There was one other that started to make, at Providence, R. I., Builder's iron foundry. No guns were received from them for the ord- nance department. 7. Q. Who are or have been the proprietors at the Fort Pitt foundry since your guns have been made? A. When I first started it was Knap & Totten ; it was that firm that made the first experiments to determine the practicability of casting guns in that way. Charles Knap's Nephews was the style of the firm during the war. That firm is now the Knap Fort Pitt Foundry Company. 8. Q. Do you know whether any officers of the government have been interested in that foundry ? A. None, to my knowledge. 9. Q. What royalty, per cent., or profit have you received on guns made according to your system ? A. In the first place, I sold to Mr. Knap my interest in the patent, for which he was to pay me one-half cent per pound on all castings made under that patent, and on which he collected royalty. 10. Q. That contract still remains in force I A. Yes. 11. Q. Can you state what has been about the gross amount of such profit received by you ? A. I could not state it exactly. 12. Q. Can you tell what was the prices -charged the government at the different foundries for this gun ! A. No, I cannot. That is on record in the Ordnance Office. I never had anything to do with the prices paid for guns. 13. Q. Will you now explain what it is in your system that you claim as original, and for which you receive a royalty ? A. My recollection is, that my claim reads something like this: " For the cooling of heavy hollow castings, intended to resent central force, by circulating within the core a cooling fluid or gas; in combination with the application of heat on the exterior to prevent too rapid cooling from without." 14. Q. In what particular does your system differ from the system, upon which was made the 12-inch coluinbiads of Colonel Boinfordf A. It differs in this, that the gun cast by him was cast solid, and cooled entirely from the exterior ; while guns cast on my system are cast hollow, and cooled in accordance with my aforesaid claim. 15. Q. Will you explain the manner in which guns are made upon Admiral Dahlgren's system ? A. I do not know that Admiral Dahlgren has any system of casting guns; he has a model and no other claim that I know of; his guns hav- ing been cast solid, or cooled from the exterior, which is no novel method of cooling. 16. Q. What are the general points of difference of models between the Eodman and the Dahlgren guns ? EXPERIMENTS ON HEAVY ORDNANCE. 65 A. In theDahlgren gun the reinforce for two or three feet between the breech and trunnions is cylindrical ; his gun then tapers rapidly to a cone, the chase being conical j while in my model there is no straight line on the exterior at all ; his cylinder being replaced by a double con- vex surface, and his conical chase by a concave surface ; my model being so constructed that, under the formula for the exterior, the chase may be continued to any extent and leave a proper thicknesss of metal ; while in the other the chase being extended the thickness becomes nothing a short distance from the muzzle ; the taper between reinforce and chase being much less rapid in my model than in his. 17. Q. What is the condition of the metal in guns cast upon your system ? A. That depends upon the rate of cooling from the interior. The intention is, when the requirements are carried out, that the metal in the gun shall be under a certain amount of initial strain, the exterior being under a force of extension while the interior is under one of compression. 18. Q. Is this condition arrived at under your method of cooling from the interior? A. Yes. 19. Q. Do you mean to have the tension uniform throughout the wall of the gun? A. No, not while the gun is free from the strain due to powder. When subject to that strain, if the initial strain be of proper tension, it would bring the whole of the thickness of the walls of the gun to the breaking strain at the same instant, and would give us the benefit of the entire thickness of the walls of the gun in resisting the force of the powder ; while any solid-cast gun, cooled entirely from the exterior, is under an initial strain the reverse of that just described, the exterior being under a force of compression while the interior in under one of extension, and the action of the powder joins with the exterior of the gun to break the interior before the exterior is brought into useful action at all. 20. Q. Do you think a 12-inch rifle gun could be made and cast of the same dimensions and weight as a 12-inch Kodmaii rifle, which could endure 1,000 rounds, by cooling it so slowly as to have the metal in a state of initial rest, or without strain ? A. I should think it doubtful whether it would. That state of things would be better than that obtained by casting and cooling from the exterior. 21. Q. Do you think the principle of initial tension necessary to be embodied in a gun, in order to have the metal perform its full share of work in restraining the action of a force from within outwards, having a tendency to burst the gun or injure the bore? A. I do consider it absolutely necessary. 22. Q. Does a gun which is cast solid, and cooled from the exterior, have the same fineness of grain and texture at the surface of the bore as a gun cast hollow ? A. It does not. 23. Q. Is there any difference in texture between the iron in the cen- ter of the block for a solid- cast gun and the exterior? A. Yes, very considerable; that difference increasing with the size of the block. 24. Q. Are there any cavities found in the center of most of the large size blocks f A. Yes; there are what they term draws. I would also remark that the more rapidly the gun is cooled from the exterior the more likely are these draws to appear. Kep. No. 266 5 66 EXPERIMENTS ON HEAVY ORDNANCE. 25. Q. At what part of the casting would they appear, providing the gun is cast to the shape at which it is afterwards to be finished ? A. It would most likely appear near the trunnion, just above where the most rapid taper takes place, the gun being vertical with the muzzle up. 26. Q. Have any cavities ever been found in the hollow-cast gun between the exterior surface and the surface of the bore T A. Yes ; we found small cavities then. One of the guns, cast at Pitts- burg, was found to have small cavities of that kind. 27. Q. Are there any differences of texture between the metal nearer the cooling surface, exteriorly and interiorly, and the middle metal of the wall of the hollow-cast gun I A. There is some difference which may be detected by the practiced eye ; the interior is finest-grained, and the exterior is next the middle is generally the coarsest, though not always so. 28. Q. Would such a cavity, or difference in texture, indicate that there were opposing tensions in the wall of the hollow-cast gun, and that those tensions, which resulted from the abstraction of heat from the exterior, were acting to assist the force of the charge to burst the gun ? A. I do not think that these textures would indicate strain at all $ they result from the difference in length of time the metal has in cooling. 29. Q. If the difference in time of cooling is not all that you depend upon to produce the initial tension which you desire to obtain, what is ? A. The initial strain is due to the difference in time of cooling, and is produced by retarding the cooling of the exterior, so as to keep it at a higher temperature during the process of cooling than that of the interior of the gun. 30. Q. Is the point in the wall of your gun which cools last, the weak- est ? A. It ought to be the weakest. In the cooling of the gun the heat on the exterior is not sufficient to prevent the congelation of the metal it simply retards the cooling of the iron of the exterior after the metal has solidified and to retain it in that condition while the interior is cooling, so that the exterior, as it afterward cools, shrinks upon the interior, a tire upon a wheel. 31. Q. Do you prevent entirely the cooling of the exterior, or is that also a cooling surface ? A. It becomes a cooling surface toward the latter part of the cooling process. It is a cooling surface to the extent permitted by the exterior artificial heat. 32. Q. Then the portion of the gun which cools last is not the exte- rior, that being at some point between that and the interior? A. Yes ; that is the case. 33. Q. Is it in that locality that you have the difference of texture or the cavities that you speak of? A. Yes ; where they occur. They are generally nearer the exterior than the interior ; but they seldom occur. 24. Q. Have you ever noticed any facts which showed that the tension in solid-cast guns, from the bore outwards, assisted the force of the pow- der to enlarge the bore or burst the gun f A. I have noticed cavities (slits like these draws) in guns, and my re- collection is, that one gun, having such cavity or slit, was fired at Alger's foundry, about or previous to the time Colonel Bornford cast his 12-mch gun and showed a very small endurance. 25. Q. Were such tensions irremedial in all large columbiads previ- ous to adopting that hollow mode of casting ? EXPERIMENTS ON HEAVY ORDNANCE. 67 A. My impression is that they were to a greater or less extent, and my system of cooling was intended to correct this defect. 26. Q. We understand, then, that the principle object of the hollow mode of casting is to have the tension reversed, thereby thus to assist the tensile strength of the iron to restrain the force acting against the bore of the gun to enlarge or burst it ? A. The object is, as before stated, to throw the metal in a hollow-cast gun upon an initial strain, the exterior being under a force of extension and the interior Milder 'one of compression, and such, that under the law of diminution of strain from the bore outward, the entire thickness of the walls of the gun should, under the action of the central force, be brought to the breaking strain at the same instant. 27. Q. What is the effect of time upon the tension of the solid-cast gun, or, in other words, would a solid-cast gun be better when new ? A. I do not think that that point is known ; 1 do not know. 28. Q. Theoretically what would be your opinion ? A. I was going to state that I do not know whether a piece of metal brought under a given extension by a tensile force and held there until it should accommodate itself to that extended length, would be weaker than if it had been left at its original position ; my belief is that it would. 29. Q. Would you cool a hollow-cast gun at any different rate, if it was to be fired to extremity when new, from that rate necessary to its having sufficient tension remaining at the end of six years to endure the same amount of firing?* A. I think I should cool a gun intended to be used immediately more rapidly than I would one not to be used in eight or ten years. This is a point in which experiments are now in progress. I have examined the tension in two pieces of metal taken from the same gun, at intervals varying from six months to two years after taking it up, and no appreci- able difference has yet been discovered. 30. Q. Do you think a hollow cast gun improved or deteriorated with age? A. My impression is that a hollow-cast gun must deteriorate after a long time ; I do not know how long before the tension relaxes. I think it must relax until it reaches the tension due to permanent elasticity. 31. Q. And if it be exactly right to bring the whole thickness of the gun to the breaking strain at the same time, this cannot be the case after the initial strain shall have been diminished ? A. No. I do not know the law of diminution of strain by time in cast iron; but we do know that within and even considerably above its limit of permanent elasticity it is a very elastic substance, or one having great longevity of strain. 32. Q. If a bar of cast-iron should be bent nearly to the breaking point and kept there for any length of time, would it recover its original form? A. That would depend upon whether it had been carried beyond the limits of permanent elasticity. If the bar was strained to near its break- ing point it would not return. 33. Q. If a bar should be held in its position for a number of years, would it recover as completely its form as if the strain were immediately removed ? A. It would not. 34. Q. On page 28, first paragraph, Kodman's book, you say: "These results appear to leave no doubt as to the superiority of the hollow over the solid-cast guns while new. What effect time may have upon them can only be ascertained by experience ; but it is difficult to understand 68 EXPERIMENTS ON HEAVY ORDNANCE. how time could ever so far change their relative endurance as to cause the solid-cast guns to surpass those cast hollow in this quality." We understand that the first 12-inch rifle Rodman gun was made about six years before it was completely tested when it burst. Did you cause a solid-cast gun to 'be made at the same time, of the same model, of the same material, and give it the same age for the relaxation of its tension you gave the Fort Monroe 12-inch rifle, so that the question of time upon the endurence of guns could be exactly determined"? A. No; there was no cast-iron guns made at the same time that that one was. 35. Q. Has the question of time upon the endurance of both solid and hollow-cast guns been as yet satisfactorily determined f A. It has not. 36. Q. Do you know of any example of a smooth-bore gun which has exhibited a superior endurance, which endurance was attributed to the length of time which elapses between the time the gun was cast and the date of its being proved ? A. I do not think of any instance of that kind now. 37. Q. Did you ever have a gun cast hollow, made of the same material, with the same tensile strength, density, model, and calibre as the gun cast in 1846 and proved in 1852, mentioned on page 217, Wade's book, and w^hich endured 2,552 rounds, (while one made and proved in 1851, which was about one-sixth stronger, burst at 72 rounds,) for comparison, by subjecting it to proof after the same time had elapsed, for the purpose of getting absolute knowledge on the point mentioned in the sixth para- graph, on page 55, Rodman's book, in which you say you do not knoAv whether a gun is better when new or after it has lain unused for a given length of time ? A. I do not think there was. I have no recollection of any experi- ment of that kind. 38. Q. What time elapsed between the casting and proving of the gnu known as the 12-inch Atwater rifle ? A. I cannot tell you. 39. Q. Do you think that the Atwater system of rifling had a tendency to increase or diminish the strain upon the gun I A. I do not see that it should have the effect to increase it. My impression is that there were three 12-inch rifles cast at the Fort Pitt foundry, and I think by an order from the Navy Department; one was to be rifled on the Atwater principle, one rifled on the plan which the navy was to furnish, and the other on a plan furnished by me. My recollection also is, that these guns were cast on a core-barrel that was too short, and in finishing them with the proper length of bore they bored through the interior hard metal around the core, thus taking away the metal that was intended to be hard and strong to resist the action of the powder on the bottom of the bore. I believe that all of these guns began to break at the bottom of the bore ; I saw one, I know, that was cracked at that point. 40. Q. Were they cooled from the exterior ! A. I do not know in what manner they were cooled ; I understood that they had cooled some guns by dropping water into the bore and letting it evaporate. That was not carrying out my system. Whether these guns were made in that way or not I do not know. 41. Q. Do you thiuk the fault in casting, to which you have referred, satisfactorily accounts for the difference of endurance between the Atwater rifle and the first rifle gun of the same calibre proved at Fort Monroe. EXPERIMENTS ON HEAVY ORDNANCE. 69 A. It is believed that the casting of the bore too short will partly account for it ; the metal may not have been as good, and I believe these guns were fired with quicker powder than that used in the Fort Monroe army 12-pounder guns. 42. Q. Have no guns of large calibre, cast hollow and cooled from the interior, burst at the foundry I A. Yes ; there have been three or four that cracked either in the pit or in the lathe. 43. Q. How do you account for that phenomena? A. On the principle that they cooled them too rapidly from the interior, and kept up the fire in the pit too long and kept it too hot. I was glad to learn that guns could be thus cracked, for I had not, till then, sup- posed it practicable to cool a gun so rapidly from the interior as to cause it to break from the exterior. There was one, I think, cracked on the lathe just as they commenced to turn it. These cracked guns show that my system of cooling covers the entire field of initial strain. 44. Q. Have you noticed any small ruptures or cracks on the outside of a gun previous to firing, cast upon your system ? A. I have noticed such cracks in one or two cases around the opening in the sinking head through which the water passes out after having cir- culated through the cavity left by the core-barrel. 45. Q. Have you ever noticed any ruptures or cracks on the outside of such guns less in extent than the complete bursting of the guns, during proof or after firing in service ? A. No ; I never have. I do not believe that we have received a gun that will begin to break on the outside first, in firing. I may say here, too, that in the manufacture of these guns a ring is taken off the sink- head contiguous to the muzzle, which ring is planed through in a radial direction until the initial strain breaks the part that is left unplaned ; from the amount that this ring opens on the exterior we deduce the extension per inch in length of the metal there. Then knowing the extension which the metal of the gun will safely endure, we can tell before the gun is finished whether or not it is over-strained, and no over- strained gun has been accepted. 46. Q. Which is the most difficult gun to make to withstand the pres- sure of the powder, a 10-inch or a 20-inch gun ? A. I do not think there is any difference. 47. Q. Do you think you could determine how best to make a 40-inch gun upon the basis of your experiments with the 20-inch gun ? A. I do not suppose that it would be possible to determine with cer- tainty, from the fabrication of the 20-inch g\m, the rate of cooling and degree of decarbonization of metal necessary to make the best 40-inch gun at the first trial that could be made by any number of additional experiments. 48. Q. Would the force acting to rupture a large gun, with a proper charge of powder, be more likely to rupture it than a small gun ? A. The larger the gun, other thmgs being equal, the greater the strain or pressure upon the square inch on the surface of the bore. This results from the greater column of metal in front of each square inch of surface pressed by the gas in the large than in the small gun ; but, by making the powder for the 20-inch gun appropriate to that gun, it would have no greater maximum pressure on the bore than the 10-inch with its appro- priate charge and powder. I have no doubt of being able to impress the same velocity upon a 40-inch shot that you do ordinarily upon a 10- inch shot, and with little, if any more, tendency to break the large than the small guns ? 70 EXPERIMENTS ON HEAVY ORDNANCE. 49. Q. Is the initial velocity of the 15-inch gun nearly uniform for like charges and elevations ? A. It is. 50. Q. And the same for other calibres? A. Yes. 51. Q. Is that an indication that the force of powder is nearly uni- form! A. Yes. 52. Q. Is the quantity of gas resulting from the combustion of a given quantity, by bulk, weight, and size of grain, uniform or nearly so ? A. Equal weights of gunpowder, being equally well incorporated, ought to evolve equal volumes of gas, irrespective of the size of grain. 53. Q. How many rifle 12 inch guns have been made upon your sys- tem? A. For the army there have been three made all experimental. 54. Q. How many in the navy? A. I think three, also experimental. 55. Q. Will you give a brief history of the endurance of these guns ? A. The first 12-inch gun, the only one that has been proved to extremity, has been fired, I think, about 480 fires ; the records will show the exact number. That gun burst, as was supposed, by the jamming and wedg- ing of the projectile in the bore; the other two guns, one made by the Knap Fort Pitt Foundry Company, and one at Alger's foundry, have not been fired to exceed four or five rounds each; the one at Fort Delaware only two rounds that I know of. The gun at Fort Delaware was made by C. Alger, and the one at Old Point by the Knap Fort Pitt Foundry Company. 56. Q. What is the present condition of these guns? A. Their present condition cannot possibly be known accurately; the one at Old Point, from the breaking of the projectile in it, has, I think, two lands slightly depressed for a length of, say four inches, at a dis- tance from the muzzle of about four feet. These guns have both been measured by the star gauge, and the enlargement ascertained to be not greater than we have frequently obtained in the proving of the solid-cast smooth-bore guns, I think, from .012 to .017 of an inch. These guns have both been subjected to extraordinary pressures from the jamming and upsetting or breaking of the projectile inside of them. 57. Do ordnance officers all agree that the breaking or bursting of the projectile is the chief cause ? A. No; not that it is the chief cause, for the reason that it ought not to occur ; but that it is a potent cause when it does occur, especially the upsetting of the body of rifle projectiles. 58. Q. Can you give any account of the 12-inch rifles made for the navy? A. I cannot. I know that they did not endure satisfactorily. 59. Q. Do you regard either of the 12-inch guns in the army as safe to be fired now with the ordinary charge I A. I think they are both so. 60. Q. Could you predict with any certainty their endurance ? A. I could not; for the reason that I do not know what effect may have been produced upon them by the extraordinary pressures to which they have been subjected. 61. Q. In many reports of the bursting of guns it is said that the rup- ture was supposed to have occurred from the breaking or jamming of shells in the bore. Why is it there is no certainty of the cause? A. When a gun bursts, and you find the shot fired at that time to in- EXPERIMENTS ON HEAVY ORDNANCE. 71 dicate jamming or wedging, or you see that it is broken, the presumption is, and I think as a rule a fair one, that that was the cause of the burst- ing of the gun at that round. JANUARY 26, 1869. Brevet Brigadier General T. J. EODMAN recalled. By the CHAIRMAN: Q. In developing ordnance power it has been determined in your mind whether it had better be by smooth or rifle bores, if the work to be per- formed is the penetration of iron plates'? A. My impression is that you can penetrate further with a rifle projec- tile than with a smooth-bore. But at moderate distances the racking effect upon the embrasure of a fort or the side of a ship or turret will be greater from the smooth-bore of the calibres now known to be practicable than with the rifle. I would also add that the smooth-bore is much less liable to extraordinary or dangerous pressures than the rifle. It is gen- erally agreed by ordnance officers of this, and I believe other countries, that racking is more destructive of the plating of vessels than penetra- tion ; I understand and believe it to be so. Q. Have you determined in your mind whether it is better to load at the breech or at the muzzle for guns of large calibre ? A. 1 have not definitely determined that question. My belief is that you can make a muzzle-loading gun stronger, that is, to resist a heavier charge, than a breech-loader. The breech-loader would have the advan- tage in embrasure, where it might close the port-hole with the muzzle ; while loading at the breech thus prevents the ingress of small projectiles during that time. Q. Is a breech-loading gun stronger or weaker than a muzzle-loader, leaving out of consideration the strength or weakness of the parts which constitute the breech -loading attachment ? A. All the breech-loading guns that I have seen are weaker necessarily than the muzzle-loaders, for the reason that the breech-loader is deprived of a great part of the stave or transverse resistance of which the muzzle- loader, has the benefit. I would say that this might be to some extent remedied by throwing the seat of the charge forward in the gun. Q. Do you think that the central metal at the rear of the bore, reach- ing through the cascable, adds to or diminishes the strength of the bar- rel of the gun ? A. It adds to the strength of the gun. Q. How in a breech-loader having a breech-pin ? A. It is not as strong as a solid breech. Q. Have you ever seen an example of a cast-iron, unbanded gun, which had ruptured longitudinally through the reinforce, in which the line of fracture was not continued through the breech or cascable ? A. I have seen examples where it was not continued through the cas- cable; the fracture will always pass through the breech, more or less ob- liquely, to a plane containing the axis of the bore. Where the breech has the proper thickness of metal in the rear of the bore the fracture is more likely to break off obliquely to the plane of the axis. Q. Is the direction of fracture, shown in the various diagrams to be found in the books usually entitled "Rodman's" and "Wade's" books, 72 EXPERIMENTS ON HEAVY ORDNANCE. the general direction of such fractures if the guns are made of cast-iron and unhanded I A. They are for the model of the gun there shown. These guns dif- fer in the breech from my present model. Q. Is there any law in relation to the strength of hollow cylinders r closed at each end, subject to a force from within, by which the differ- ence in tendency to burst longitudinally or transversely can be deter- mined ? A. I do not know that such a law has been determined ; but, practi- cally, that point can be determined, and a result will be found in my printed report of experiments. I would state, too, that when the distance or length of bore acted upon by the internal force is such that the tan- gential expansion of the metal at the point of rupture will not admit of the bending of the stave to an extent required to rupture it transversely longitudinal, fracture will take place. If that distance be so short that the length of stave acted upon will break transversely before extending the metal to its breaking point tangentially, then transverse rupture will first take place. Q. Do you think that this explanation fully accounts for the trans- verse ruptures which have sometimes occurred in guns of large calibre I A. I do not know that it does fully. We have transverse ruptures which occur from longitudinal rupture having first taken place ; for instance, rupture at the breech may extend forward until one piece or the other shall break off with a transverse fracture at its front end. Q. If it be the pressure of the powder against the surface of the bore that is the cause of the bursting of guns, how can you account for the breaking through the breech to the rear of the continuation of the bore? A. From the breech being too thin, or from the metal being very soft, thus allowing the bottom of the bore to be pressed back until interior annular rupture takes place. This subject is illustrated by my experi- ments on small cylinders to be found in my printed reports, plate 7 and page 153. . Q. In treating of the transverse strain, on page 47 of your work, have you not shown a form of fracture which never occurs to a gun burst under fire? A. I cannot say whether I have or not. That plate is intended to illus- trate the form of the fracture that ought to occur when transverse frac- ture of a gun occurs before longitudinal fracture. Q. Is not the kind of fracture you have shown by diagram on that page the kind which would result from the action of all the different kinds of strain to which you have alluded, viz : " the tangential strain," the longitudinal strain, and the strain of compression exerted from the axis outward I A. Yes ; when the surface pressed was so short as to cause transverse rupture to first occur. I would also state that this diagram is an almost accurate representation of fractures that occurred in small cylinders, where transverse fracture first occurred, as on plates 4 and 5 of my reports. Q. Yet that is not the usual kind of fracture to be seen in guns which are burst in firing I A. I do not know that I have ever seen one of exactly this form j for the reason, I think, that the length of bore pressed at the instant when rupture begins, is generally greater than that which would first produce transverse rupture. Q. Then you think that the rupture does not occur until the projectile has made a start towards the muzzle ? EXPERIMENTS ON HEAVY ORDNANCE. 73 A. No the projectile will always have made some progress towards the muzzle before the breaking strain is reached. Q. Are not the principal pieces forming the reinforce into which a large gun is usually broken when it is burst in firing most frequently thrown to the rear? Would not that indicate that the rupture began forward of the trunnions and split the gun backwards through the breach I A. They are ; for the reason that the gun has commenced to recoil, and the motion of recoil, combined with their lateral motion, forces the pieces obliquely to the rear. Q. Would not that indicate that the rupture began forward of the trunnions to split the gun backwards through the breech ? A. No. Q. Is not the pressure of the powder reduced by being expanded into the increased space it would have when the shot had moved forward in front of the trunnions ; can there be force enough left to start the rup- ture at that point first, when it is remembered that the time of the action of the force against that part of the bore is so much less than the time of action in the chamber ? A. The pressure of the gas, after it has attained its maximum pressure, diminishes as the shot moves forward, and rupture ought not to take place forward of the trunnions in a properly modelled gun. Q. Does it take place in a model of your own u ? A. I do not think it does, unless from the breaking or jamming of a shot or shell in the chase of the gun. I have not seen one broken that indicated that it had, without this cause. Q. Can you tell at what point the gun would commence to rupture, if you knew at what point in the bore the projectile jammed'? A. It ought to commence at the thinnest part of the gun, behind the projectile, or at its then position. Q. Are not the fractures of the hollow cylinders, shown by shaded drawings following page 144 of your book, principally like the theo- retical fracture shown on page 47 ? A. Some of them are and some are not. Q. Is it not noticeable that but few of the fractures of these cylinders are through the breech part, as we see them in most the large guns which have burst in firing ? A. Yes ; and for the reason that the thickness of metal in the breech of the cylinder was proportionally greater than that in the gun. Q. Do you think a 10-inch gun-block, cast solid and bored, as if for a gun, and before it was turned on the outside, subjected to water pres- sure, could be burst in> such a manner as to have the fracture through the breech the same as the fracture usual in the gun burst by firing ? A. I think it might. Q. Would the longitudinal tension in a similar block, cast hollow, have the tendency to direct the fracture through the breech, or other- wise? A. I think it would have a tendency to extend the fracture through the breech, which would increase the strength of the gun. Q. Opposite page 13 of your work there is a diagram of a 10-inch col- umbiad, number 332, cast solid,* looking at the diagram, would you think the fracture began forward of the trunnions or at the breech end ? A. At the breech, unquestionably. Q. On page 14 you say (referring to the gun last mentioned, and to the hollow cast 10-inch gun, No. 331, which burst also) that it is quite evi- dent that the fracture began at the breech in both cases ; yet the large piece of the reinforce from the hollow-cast gun was thrown to a great 74 EXPEEIMENTS ON HEAVY ORDNANCE. height, and to the rear. Would not that indicate that the rupture began first at the front ? A. No $ for the reason, as I said before, this rear motion conies from recoil. Q. Is that sufficient to project the exploded part to the rear in the manner described ? A. Yes ; I think so. Q. On page 14 you say (referring to the splitting of guns through the breech) this has been the case with every columbiad you have ever seen broken and indicates the breech as the weak point. Has any greater strength been added to guns which have been made since 5 and if so, has the fracture been different in such guns I A. A greater strength has been added to the breech in my model of gun. I cannot say whether the nature of the fracture has been changed or not. Q. If you should find the character of the fracture to be the same, do you think you could remedy it by adding still greater strength to the breech ? A. I have no doubt of it. Q. Are you aware that the first 15-inch hollow-cast guns made for the navy were about three feet shorter than the army 15-inch gun to accommodate them to the diameter of the turrets ? A. I know that they were considerably shorter ; but exactly how much I do not know. They were also thinner at the muzzle. The wall or metal was about three inches thick at the muzzle, while in my model a 15-inch gun which is longer is five inches thick at the muzzle. I do not know what the model of the navy gun was as cast. Q. What is the thickness of wall at the muzzle in the army 15-inch gun? A. The thickness of the finished gun is as before stated five inches, the diameter of the cast gun at the muzzle is, I think, 38 inches. Q. Have you been informed that three of the 15-inch guns of the eight used against Fort Fisher burst at the muzzle ? A. I have understood that some 15-inch guns did ; I do not know what number. Q. Would those guns be stronger if made still thicker than seven inches ! A. Yes ; they undoubtedly would be if under proper initial strain ; those that burst were not seven inches thick, nor anything like it, being as before stated only about three inches thick at the muzzle. Q. Are you aware that the navy reduced the thickness of the muzzle afterward to about three inches, and reported that the gun was not weak- ened thereby ? A. I do not remember that they reduced their guns after the burst- ing of those at Fort Fisher ; I am aware that they did reduce them below the thickness of the army gun in order to get them through their small port-holes. Q. What, in your opinion, has caused the bursting of navy 15-inch guns, and some of the larger Parrott s, at the muzzle ? A. The bursting of the navy 15-inch gun I have no doubt was due, either to the want of metal about the muzzle, or to the bursting of shells within the gun. In the Parrott gun the bursting may have been due to the bursting of the projectile in them ; but I think the most potent cause was the too rapidly increased twist in the chase of the Parrott gun. I have examined the fracture in some, and found it to be very nearly of the same character as fractures produced in hollow cylinders by torsional strain. EXPERIMENTS ON HEAVY ORDNANCE. . 75 Q. If it should be demonstrated that guns with three-inch thickness of wall at the muzzle had more endurance than those with seven-inch thickness of wall, how would you account for it? A. I should account for it on the supposition that there was an adverse initial strain on the metal in the thicker gun, independently of any action of the powder. Q. Is not the strength of the wall of the muzzle to resist a rupturing force from within improved by turning off the outside metal which exerts an opposing tension, as referred to in one of the previous questions? A. Not in the hollow-cast gun, nor in any gun under a proper initial strain. Q. Would a shell exploding prematurely in the muzzle of a gun cause a deep indentation, which would remain as evidence of the force if it should burst the gun? A. The chances are that it would. Q. Have you ever noticed any such indentation in the surface of the bore at the place of rupture, which would enable you to determine that such a force had acted to burst the gun ? A. I have not examined any of the 15-inch guns broken at Fort Fisher. Q. If the. projectile did not make any indentation, crack, or enlarge- ment, which could be seen after a premature explosion, could the gun be injured to an extent which would cause it to give way afterwards with a shell which did not burst, and have the subsequent rupture reasonably attributed to the previous premature explosion? A. That might or might not be with a rifle projectile. I can under- stand that it might wedge so tight as to produce a strain; such as to so- far weaken the gun that it might break at a subsequent fire and not visibly mark the bore. It is a matter of record that in proving solid- cast guns they have stood the proof of double charges and double shot, and burst at the first service charge after. Q. Have there been any experiments that have ascertained positively whether the premature explosion of shells in the bore of a gun will rupture it? A. 1 do not know of any. Q. What is your opinion ? A. My opinion is that the explosion of the shell in the bore of a gun subjects the gun to an undue strain, which may or may not be sufficient to burst it. Q. What is the meaning the term work, referred to in modern essays on artillery, in relation to projectiles, and what is the footpound or foot ton referred to in that connection ? A. The foot pound is one pound avoirdupois, raised one foot vertical lift. Q. Is there not an equivalent of heat for foot pounds or tons, and a mechanical equivalent of foot pounds for a unit of heat, called Joule's equivalent? A. Undoubtedly so. The present theory is that heat and work, or living force, are convertible one into the other, or that heat is due to molecular motion. Q. What is the mechanical equivalent for a unit of heat? A. I do not, with certainty, remember that now. I believe it is stated to be that amount of heat or fire effort necessary to raise one pound of water one degree in temperature, and that its equivalent in work is equal to raising 774 pounds one foot high; I am not positive as to the figures. Q. Would it not be possible to determine the amount of tension in a hollow-cast 15-inch gun, upon the basis of the units of heat, proportioned 76 - EXPERIMENTS ON HEAVY ORDNANCE. to the whole number in the melted iron, communicated to the water flowing through it, and upon the equivalent in foot pounds for that heat? A. I do not now see how you could do it. If you knew just how much of that heat was taken off from the surface of the bore, and how much from the exterior, and the times at which they were taken off, I suppose an approximation to the strain or tension upon the metal could be made ; but I should greatly prefer to rely upon the results obtained from the ring taken from the muzzle of the gun to a calculation made on this basis. Q. If a sufficient number of shots were fired from the 15-inch gun with a sufficient rapidity, and each of them upset or fitted so tightly in the bore as by friction of rubbing against its surface to retard its motion to the extent which would just permit each shot to move .to the muzzle and stop, having expended all the force of the powder, sufficient heat would result to melt the gun to the same state of fluidity from which it was cooled when cast, would it not? A. Undoubtedly sufficient heat would result from a sufficient number of shots fired with a sufficient rapidity; but I know of no means of accom- plishing that feat at this time. Q. Might not the tensions in a hollow-cast gun be so increased by friction, resolved into heat in this manner, as to burst it ? A. Not with our present means of rapidity of firing, and a gun having a proper initial strain. Q. Is it not more probable that the friction which results in heat, communicated so suddenly to the surface of the bore near the muzzle, is the cause of the rupture of guns at that part, than that the bursting of shells in the muzzle is the cause of the bursting of the gun f A. I do not think so. Q. Which would create the most friction against the surface of the bore, a rifle projectile or a spherical projectile f A. A rifle projectile. Q. Do you think that the additional heat communicated by the fric- tion of the projectile upon the bore of rifle guns acts to any great extent as an additional force to aid the powder in rupturing the gun? A. I do not. In a gun free from strain when fired, additional heat communicated to the interior of the metal beyond that of the exterior will increase its resistance ; for, generally, in guns where the initial strain is too small, additional heat at the interior will increase its resistance ; while in those where the initial strain is too great, excess of heat of the interior over the exterior acts to diminish their resistance. Q. Have you ever made any estimate of the number of degrees the surface of the bore would require to be raised suddenly in temperature in order to burst the hollow-cast gun I A. No, I have not. I know this, though, that the expansibility, per inch in length, of good gun metal (cast-iron) is about .003" of an inch, while the expansion of cast-iron from 32 to 212 is put down in the books at a little over .001" of an inch per inch in length. It would, therefore, require a gun to have an initial strain which would produce at least .002" of an inch extension per inch in length, onthe exterior of the gun, in order that a difference of temperature between the interior and exterior of 180 should at all endanger its safety. Q. In speaking of the tensions which result from cooling a gun from the interior, in answer to a previous question, you only referred to the tangential strain. Would there -not also be a longitudinal contraction of the outsifte after the freezing of the interior I A. Certainly there would. EXPERIMENTS ON HEAVY ORDNANCE. 77 Q. What would be the effect of inserting heated shot in the bore of a gun so strained tangentially and longitudinally? A. The tendency would be to unduly increase the initial strain of a gun that was already under a proper initial strain before its insertion. Q. Would the effect of this force generated by the heat be to enlarge the bore of the gun ? A. It would have the effect to enlarge the bore of the gun, and to increase the initial strain if a proper one, and to diminish it if an improper one, before its application. Q. Whatever force tends to enlarge the bore of a gun is a force having a tendency to rupture the gun, is it not ? A. That depends entirely upon the condition of the gun as to initial strain before the application of such force, and upon the nature of the force. If the. force result from excess of heat on the interior of the gun, it would be beneficial where the initial strain is much too small, and hurtful where it is too great. If the force be purely a mechanical one, its tendency will be in all cases to burst the gun. Q. On page 47 of your book a diagram is shown dividing a cross- section of a gun into voissoirs or staves, and you speak of the effect of pressure as having a tendency to bend these staves outward in the mid- dle of their length, as shown by the first diagram on the page. The effect of cooling from the interior edge of the stave is to reverse that curve and give each imaginary stave the strong tendency to burst the other way, is it not ? A. It would. The effect, however, is beneficial in a gun having a proper or too small an initial strain, as it increases the length of the bore, along which the transverse resistance acts beneficially. Q. Then, if any heat should be added to the inner edge of the stave afterwards, when the gun is in use, the tendency to still further bend it would result, would it not? A. It would. And to still further increase the length of bore that would offer transverse resistance, unless the initial strain were already too great. Q. Will not this tendency to bending outward of the staves from after heating the gun cast hollow, from the direct communication of the heat of the powder, gas in motion, or the indirect heat which may result from the friction of the shot, account for the breaking of the gun through the breach ? A. No; not unless the gun be previously under an unduly great initial strain. Q. Is there, ordinarily, much heat communicated to the surface of the bore by contact with the hot gas of the powder? A. There is considerable heat communicated; but the conducting powers of the metal are such as to disseminate the heat communicated to the bore through the mass of the metal, so as to render the difference in temperature between the inner and outer surface of the bore so small as not to be injurious with our present most rapid rate of firing upon a gun, either free from strain or having a proper initial strain. Q. Is the fact that there is not more heat communicated partly because gasses are non-conductors of heat, and after the gas, which is in actual contact, has given off its increment of heat, it becomes comparatively cold and is then interposed as a non-conductor between the hotter gas and the surface? A. I think that may be so. Q. Where a current of hot gas is passing rapidly over the surface, is the condition changed to any degree! 78 EXPERIMENTS ON HEAVY ORDNANCE. A. The condition would undoubtedly be changed, and more heat would be communicated in a given time. Q. Would net the surface of the vent receive more heat on this account than any other equal surface in the bore of the gun? A. Undoubtc dly it would. Q. Do you tLink the heat which is communicated to the metal which surrounds the vent has, by causing a cylinder of metal which has the vent for its axis to expand unduly, any tendency to cause the line of fracture when a gun bursts to intersect the vent ? A. I have no doubt that it has a tendency that way, but it is not so great as invariably to cause the fracture to pass through the vent. Q. Do you not think that the increased amount of heat, which will be communicated from the rapid passage of the hot gas past the windage, over the top of the shot, has the tendency, by heating the top of the bore over the shot more than any other part, a tendency to cause the plane of fracture to take the direction usually observed to be perpendicular? A. I don't know that it would. Q. Within certain limits, and in a gun not having tension enough to resist the pressure of the powder in the best manner, might it not have increased strength to resist the pressure if it were heated from within to the extent, for instance, that would just create the best degree of tension ? A. Yes ; a gun not having sufficient initial strain might be brought to it by heating the interior. Q. Do you think that guns cast solid would be stronger after having become heated by successive fires to a certain extent ? A. I do. My experience is, that in firing solid-cast guns to extremity they are more likely to burst at the first fire in the morning than at any other time ; and that they would have stood a greater number of rounds if the firing had been continued while the gun was warm, I doubt not. Q. Then it is not true that the gun that is so constructed as to embody the degree of initial strain necessary to its restraining the elastic pres- sure which the powder exerts in the most effective manner is put in the worst state of tension as regards its ability to resist the force with which its interior would enlarge as it is heated by the gas or the friction of the powder or projectile upon its interior surface ? A. If no margin had been allowed for the effects of the heat, on the interior, in fixing the initial strain, the interior heat would act injuri- ously. Q. Then you think if the gun had too much or too little tension it would be in a bad condition to resist the expansive forces of heat ? A. If the gun had a too great initial strain, interior heat would act injuriously ; if it had too little initial strain, it would act beneficially. Q. How if it had no initial strain at all ? A. It would act beneficially ; if the initial strain had been adverse it would also be beneficial, and in a still higher degree. Q. Was the firm-name or style Knapp & Wade at any time during your experience with the Fort Pitt foundry ? A. Either Knapp & Wade, or Knapp, Wade & Co., I am not positive which, was the style of the foundry at one time. Q. Do you know whether Major Wade was at any time a partner in the Fort Pitt foundry while he was in service as an officer of the army or a clerk in the Ordnance Office ? A. I have no positive knowledge on the subject ; but my firm belief is that he was never connected with the foundry as partner while in the employ of the government in any capacity. EXPERIMENTS ON HEAVY ORDNANCE. 79 Q. What was the date of the last patent issued to you or to Mr. Knapp for the hollow mode of casting guns ? A. I only had one patent. My recollection is that that was issued in August, 1847, and renewed in August, 1861, for seven more years, and that it expired in August last. Q. Has any patent for the same thing, or for a similar invention, been given to Mr. Knapp or any other parties ? A. No, not to my knowledge. Q. Have you applied for still further extension ? A. No, I have not. JANUARY 27, 1869. Brevet Brigadier General T. J. EODMAN recalled. By the CHAIRMAN : Question. You informed us yesterday that work and heat are con- vertible. Are we to understand you, from that statement, that as one is expended the other is evolved, and vice versa ? Answer. Yes ; or, in other words, the living force of work stored up in a shot in motion, for example, will, on arresting or reducing the veloc- ity of the shot, be converted into heat or molecular motion. The quan- tity of heat developed and the work remaining in the shot at any instant of time being together exactly equal to the quantity of work originally in the shot. Q. Will you state the average rate of extension, per inch, within rup- turing, for gun iron ? A. It will run from .0025" to about .0035" of an inch per inch in length ; the best ought to extend (.0035") 3 thousandths of an inch per inch in length, before breaking. Q. Also the average rate of extension per inch within permanent elas- ticity for gun iron '? A. Good gun iron will run from 8 to 12 thousand pounds per square inch, while its permanent elasticity will not be sensibly or very injuriously impaired inside of 15,000 pounds. I find in this sample, tested here, (referring to the book,) the absolute limit of permanent elasticity is 9,000 pounds per square inch; the specimen extended (.00043") Toinroo^ of an inch, having a permanent set of (.00001") 1 ^ of an inch ; and at 15,000 pounds the same specimen extended (.00080") T Q^O f ari inch, and had a permanent set of (.00007") jo-oWo f an inch- Q. What is the additional temperature, in degrees, which gives expan- sion per inch equal to the extension to the limit of permanent elasticity ? A. That would require some calculation. Q. Could you approximate it ? A. It would take about 80 to expand the metal to an extent equal to the extension for good cast-iron at the limit of elasticity. Q. What increase of temperature, in degrees, will give expansion per inch equal to the average extension to the breaking point? A. It would take about 600, supposing the expansion of the metal to be uniform between the limits of 32 and that point. Q. What was the difference of the rate of cooling employed when a 15-inch gun was cast which ruptured longitudinally in the pit, and the one to which you have alluded, as showing that your mode of cooling- did give the required initial strain i. e., what was the difference of temperature between the exterior and the interior at the instant each froze? 80 EXPERIMENTS ON HEAVY ORDNANCE. A. I do not know what the exact condition of the temperature was. My impression is that the metal was at the same temperature inside as p.ut when it congealed; but I have no doubt that it congealed^rstf on the inside. Q. You have stated that you accelerate the time of cooling a hollow gun to about half the time required to cool it entirely from the exterior. What is the time usually required to cool a hollow cast 15-inch gun, and is the time nearly uniform for that size of gun ? A. It is almost uniform ; it is intended to be uniform, and generally occupies about six days. Q. What difference of temperature between the interior and the exterior, while cooling, have you noticed as giving the best state of strain in a gun cast hollow ! A. We have not been able to determine the temperature of the gun itself upon the exterior ; we have only ascertained the temperature of the pit in which the gun-flasks were, and the change in temperature of the ingoing and outcoming water. My recollection is that the tempera- ture of the water is about 156 as it comes out just after casting ; it would come up to that as the highest point while the water circulated through the core-barrel. After the core-barrel is removed the water circulates through the cavity left, by which the water is raised to a temperature something less than 212, so that it does not make steam ; this temperature gradually recedes. As the gun cools, the temperature of the pit is generally from 500 to 600 during the first two days ; then the pit gradually cools as the gun cools, the water circulating all the while. Q. Heretofore, in speaking of cast-iron, you have called it a good con- ductor, saying that heat was quickly dispersed throughout the mass. Is it a worse conductor while it is being cooled in the foundry pit ; if not, how can there be so great a difference between the interior and exterior while a gun is being cooled ? A. In cooling a gun from the casting temperature we start with a very high temperature, so that the difference in temperature between the interior and exterior cooling surfaces is very great, that of the interior being not above 200, while the exterior is at a red or even a white heat ; and w T e know that the greater the difference in temperature of the heat-receiving surfaces, the greater will be the difference in tem- perature of the heat-imparting surfaces; or the more rapidly a body receives or parts with heat the greater will be the difference in tein- derature at the surface, and at a given distance, within the body, from its surface. In practice, in firing heavy artillery, the heat is so slowly applied that the difference in temperature of the exterior and interior surfaces of the gun isnever great. Q. General, here is a target record of the firing of the 12-inch Rod- man rifle gun, which burst at Fort Monroe at the 472d round. Will you please examine it and inform us if the record shows the cause of the bursting of the gun I A. The only thing that would indicate the cause of the bursting at that round is the indication of the shot having jammed in the bore of the gun, as shown by the impression of the lands of the gun upon the surface of the shot. Q. What is the character of fracture ! A. The fracture is longitudinal, and deviated when it reached within about four feet of the muzzle a little shorter on one side than the other. Q. Would this fracture indicate that the breech was not thick enough ? A. Yes ; that would indicate that the gun would be strengthened if EXPERIMENTS ON HEAVY ORDNANCE. 81 the thickness of the breech was increased; however, though the line of fracture should run through the middle of the gun, leaving the two sides almost equal, it would not necessarily indicate that the breech was too weak. Q. In what part of this gun do you think the rupture began? A. My impression is that it began at the rear part of the gun ; it is possible that it may have commenced at the fore part of it, though the manner in which it broke indicated that the crack was running forward at the point where transverse rupture first occurred. Q. Was the distance any of the parts were thrown great ? A. About 21 yards seems, from the report, to be the greatest distance to which any of the pieces were thrown. Q. What was the direction in which the parts were thrown ? A. About 10 to the rear, I believe. I understand that two fell on the right, about 10 to the rear, from a perpendicular line to the right, across the line of fire. Q. Is it probable that any of the parts were thrown upward to a great height ? A. I think not, from this fracture, (referring to a drawing shown.) Q. Were there any cracks or flaws shown on the surface of the bore previous to the rupture ? A. It is said here, referring to report, that none were discovered. I examined one-half of the gun myself after it was broken, and discovered no indication of previous deterioration. Q. Would this indicate that the gun had the proper degree of tension? A. I cannot tell whether or not ; there was no ring taken from this gun. It was the first gun of that calibre cast, and was cast before I began to take rings for initial strain. Q. Are not all the indications such as would show that the rupture began on the top almost simultaneously for the whole length of the gun? A. I do not know that they are ; the two pieces into which the gun was broken being so nearly equal, the line of fracture might have run forward. I think it is highly probable, however, that nearly the whole length of the longitudinal fracture was made at the same time. If the shot had jammed a little in rear of the first cross fracture, the pressure of gas would have been acting upon the whole length of bore behind that; and if the fracture had commenced at that point it could, and most likely would, have produced just such a fracture as is shown. Q. What pressure per square inch upon the surface of the shot, indented as in the report, would be the least which could cause the in- dentation or marks referred to in the report by Colonel Bagler ? A. I could not tell you that. Q. Do you know the limit of pressure upon the square inch of surface for metals rubbing together at which lubrication ceases to be advantageous ? A. No, I do not. It would be different in different metals ; and it ceases to be advantageous whenever the pressure is so great as to cause the interlocking of the particles of the rubbing surfaces. Q. If the pressure were greater than the limit referred to considerable friction would result as the shot was sliding along the bore ? A. Yes ; a great amount of friction would be the result. Q. Might not this friction account for the reduced velocity of the shot? You will notice round 405 had 40,000 pounds' pressure and 1,208 feet velocity, while the last round, at which the gun burst, No. 472, with the same pressure, gave only 990 feet velocity. A. Yes ; to some extent. Suppose the shot had jammed at say to Eep. No. 266 6 82 EXPERIMENTS ON HEAVY ORDNANCE. of the distance from the bottom of the bore to the muzzle, and the gun burst ; then the shot would leave with the velocity which it had at that point. Whatever friction existed tended to diminish the velocity of the shot. Q. Might not this friction so heat the interior of the gun as to cause increased tension tangentially sufficient to cause the rupture? A. No, I think not 5 it has not time to act before the shot is gone. Q. Would not the increased tension, by bending the staves outward at the ends, have the tendency to cause the fracture through the breech ? A. Yes ; though I think not to any appreciable extent. Where a con- siderable length of bore is acted upon by the gas the whole stave is car- ried out bodily, except at the extremities ; but only so far as the tan- gential resistance or extension of the metal will permit them to go, the stave resistance being of no appreciable value beyond, say, five calibres in length. Q. Has this gun the increased thickness through the breech you have previously referred to in answer to a question, and which you believed would have a tendency to prevent breaking through the breech ? A. My recollection is that the gun had a thickness in the breech of something over a calibre and a half, which experiment has shown, with small cylinders, to be about as much thickness as was valuable, there being very little increased resistance from greater thickness. Q. Do you now, in view of the results of that experiment, propose to still further strengthen the breech of the gun ? A. No, I think not, unless we should find that guns break generally in such a manner as to indicate that the breech is too thin. Q. Will you examine the record of the 12-inch hollow-cast gun, called the Atwater gun, which burst at Fort Monroe on the llth of January, 1866, and inform us if it did not break through the breech 1 A. The data here given is not sufficient to form a correct idea ; from the report I should think it probably did. Q. Did the 8-inch Eodman rifle which burst December 4, 1865, burst through the breech ? A. I do not know. This report does not state whether the gun broke through the breech or not. Q. What was the nature of the rupture of the 8-inch Kodman rifle which burst on the 3d of January, at the 86th round ? A. My recollection is that that gun burst at eighty-odd fires j that gun was made for grooved projectiles exclusively. We found that in firing with equal charges of powder and equal weights of projectile the pressure-gauge indicated, almost invariably, a greater pressure behind the grooved projectile than behind the expanding one. The initial velocity of the grooved projectile was generally a little less than that of the expanding projectile. I do not know the nature of the fracture. Q. Will you examine this record relating to the 13-inch Eodman gun which burst July 27, 1864, and state if the gun did not rupture through the breech? A. That gun broke through the breech, as shown in this report. I have not examined the fragments of the gun. Q. Was not this gun made after the latest improved model? A. I believe it was. Q. What was the thickness of the iron at the breech ? A. I think it was about the same proportion as other guns of my model j that is, about a calibre and a half thick. Q. What was the tensile strength of the iron of which the gun was made ? A. 1 do not remember. EXPERIMENTS ON HEAVY ORDNANCE. 83 Q. To what extent did the tensions due to the rate of cooling from within add to the ability of this gun to restrain a pressure from within ? A. I cannot tell you to what extent ; there was no ring taken from that gun, either. Q. Suppose this gun had been cast parallel with its largest diameter and closed with a similar breech at both ends, what pressure per inch of water should it have borne without breaking, on the supposition that all the parts of the wall were brought to the breaking strain at the same instant ? A. If the pressure should act along the whole length of the gun, you would have none but the tangential resistance to overcome ; and if the entire thickness of the walls should be brought into play, or to their breaking strain at the same instant, the interior pressure required to burst it would be about 64,000 pounds to the square inch. Q. Do you notice that shot No. 735 has the pressure recorded of 180,000 pounds per inch; is that the pressure recorded by the Rodman instrument ? A. I presume it is ; I do not know certainly. Q. Is that instant pressure, or is it momentum I A. It is mainly pressure ; there is a small amount of momentum, not enough, as I believe, to materially affect the indications of pressure; it may vary, in a pressure of that magnitude, as much as 5,000 pounds to the square inch. It is not claimed for this instrument that it gives abso- lutely and accurately the pressure of the gas in the gun, but it is claimed that it is a valuable guide to artillerists and gives indications of pressure sufficiently accurate for practical purposes. Q. Do the indications of pressure given by the Eodman instrument resemble the results got by Colonel Bomford's experiments in firing a steel ball from a hole drilled in the side of the gun ? A. No; that depends upon a different principle. Colonel Bomford inferred the pressure of gas on the gun from the number of thin pieces of pine which a pistol ball thrown by the gas of the gun would penetrate. The ball in that barrel, placed behind the seat of the shot, and where the maximum pressure is always found, was so light that it was thrown out before the full pressure of gas in the gun had been developed, and thus indicated a less pressure than actually existed. Q. Do you think there is any difference in the pressure between that which acts upon the bottom of the bore or the top ? A. In the gun that has windage of considerable magnitude the pres- sure on the top will be a little less than that on the bottom, but not materially so. Q. Is there equal pressure to the square inch against the rear of the projectile and against the bottom of the bore or chamber? A. No; there is a little more against the bottom of the bore, else the gas would not move from it the gas would move towards that point where the least pressure is found. Q. As the shot moves forward towards the muzzle, is the pressure reduced on account of the increased space into which the gases have expanded ? A. Undoubtedly it is. Q. As the pressure is reduced against the rear of the shot, is it also reduced as against the bottom of the bore or chamber f -A. Certainly it is. Q. Are the indications of the internal pressure instrument equal to the indications of an external instrument and inserted in a hole drilled through the side of the gun ? 84 EXPERIMENTS ON HEAVY ORDNANCE. , A. There has always been found, where the two were used together, a slight difference, the outer one being a little greater. The difference is supposed to result from the presence of the internal pressure gauge in the powder, thus retarding the rate of inflammation of the charge ; the momentum of the gas that strikes against the piston in either case is very trifling. Q. Have you ever had indications from the external instrument of higher pressures at two calibres from the bottom than at the bottom of the bore ? A. There is no such case that I now remember. Q. Most of the tables of pressures in your book are means for a num- ber of rounds, are they? A. Yes ; they are generally so. Q. When the external instrument indicates the highest pressures, the shot has begun to move and has left its original position, has it- not i A. Yes ; it must have moved from its original position before the gas has reached its maximum pressure. Q. At that period of time, is the pressure against the piston of the instrument against the rear of the shot and against the bottom of the bore the same ? A. They are nearly the same; there would be in theory a little greater pressure against the bottom of the bore than against either the shot or the instrument ; but not perceptible in practice. Q. Suppose there was another instrument inserted at the bottom at that instant; would it also indicate the same pressure as the other instrument ? A. Yes ; in practice it would. Q. On page 176 of your book is a table of pressures at different points along the bore; at bottom a mean of three fires with coarse powder you have 10,000 pounds; at two calibres from bottom, 26,001 pounds, pressure. Can you account for this incongruity, except upon the theory that the hole in the side of the gun was obstructed by the grains of powder at the bottom and not obstructed at two calibres! A. That may possibly have been the case. I know of no other. Q. How can you account for the other incongruity, that at 14 calibres the pressure was greater than at 12? A. In this way: these are indications that were made on disks of cop- per. It is believed to be due to the vibration of the metal in the gun after the shot has left striking the knife edge into the copper disk. If placed in a thin walled gun, towards the muzzle, it would be found to be almost invariably the case that one could see th emarks of the indent- ing tool in the copper, showing that it had struck quite a number of times, and that it had thus increased the (length of) cut in the copper which indicates the pressure. Q. Were all the holes drilled at right angles to the axis of the bore, or was the hole at 14 calibres inclined forward ? A. My recollection is that they were all right angles to the axis of the bore. Q. Have you ever noticed any indication of the instrument which would lead to the conclusion that projectile force is what you measure instead of pressure? A. No, I have not. Q. Is it not the pressure of the powder which ejects the shot from the gun and gives it its velocity? A. The pressure evolved from the powder does it. Q. How is it that there is so little difference in velocity to the shot, EXPEEIMENTS ON HEAVY OKDNANCE. 85 while the pressures from the same powder, in the same gun, vary from 8,000 pounds pressure to 180,000 pounds? A. The small differences of the pressure are, to my mind, most readily explained on the supposition that the charge is not ignited at each dis- charge in the same manner. A primer that only succeeded in igniting a single grain or so at a single point, will not give such pressure as a stronger primer that darts its volume of flame clear through the charge of powder ; the origin of ignition being a point, in one instance, and a cone running through the entire charge in the other. These extraordi- nary differences that are found, I believe to be due to the irregular action of the projectile, the wedging, or jamming, or breaking, of the shot in the bore, for I do not see how the knife edge can be driven into the cop- per without pressure, nor how pressure can exist in the bore of the gun without forcing the knife edge into the copper. Q. Was the model of the Kodman gun based upon the indications of this instrument ? A. My recollection is that it was so in part. Q. Would the steel ball fired from Colonel Bomford's experimental gun have had higher velocity at two calibres from the bottom if a musket barrel had been inserted in the hole in the side of the gun to increase its length, and the time of action of the pressure ? A. Undoubtedly it would. Q. On page 197 you have a table showing pressures at different points along the bore in guns of three different calibres, 7-inch, 9-inch, and 11-inch, showing the velocity of the shot due to equal columns of powder, behind equal columns of metal. If the pressures had been greater in one of these guns under such circumstances the velocities would have been greater, yet the < velocity is remarkably alike from the three guns for a mean of ten fires, while the mean pressure is three times as great in the 11-inch gun as in the 7-inch, and twice as great in the 9-inch as in the 7-inch. How do you account for that ? A. I do not know that I can account for it. The only explanation that I can see applicable to it is that the powder is more rapidly inflamed in a large than in a small calibre ; this would give increased maximum pressure of gas without materially increasing the velocity of the shot. Q. Has the length of the hole, from the axis outward, in which the pressure instrument is inserted, which is greater in the 11-inch gun because of the greater thickness of wall, nothing to do with it ? A. I do not think it has, not to any appreciable extent. Q. Have any smooth-bores of large calibre burst when fired with solid shot ? A. None except one 13-inch, by experiment, of my model. Q. What is the cause of the bursting of the experimental gun made upon your model, of which you speak? A. It was worn out, having burst at the 738th fire ; the pressures of the last five rounds, with 55 pounds of No. 5 powder, were 152,000 pounds, 170,000, 180,000, 200,000, and 160,000 pounds per square inch. Q. Does solid shot jam in the bore of a gun? A. They may do so if made of very soft iron and fired with very quick powder. Rifle shot are more liable to upset than round shot. Q. What was the character of the fracture in these guns which burst? A. That of the 13-inch gun before referred to. Q. What is the usual character of the fractures of solid cast guns that have burst when fired with solid shot? A. Very much the same, as far as I have observed, as shown in my printed reports. 86 EXPERIMENTS ON HEAVY ORDNANCE. Q. What is your theory to account for the bursting"? A. That they have an adverse initial strain where the metal is good. Q. Where a gun burst from the jamming of a shell in the bore, is the pressure indicated by your instrument largely increased*? A. Certainly if the gun has not been previously injured. Q. I observe that the 12-inch rifle which burst at Fort Monroe endured a pressure of 62,000 pounds without bursting or apparent injury to the gun, while it afterwards burst under a pressure of about 49,000 pounds. A. I can only account for that on the supposition that the large press- ure and previous service to which it had been previously subjected had weakened the gun, so that this pressure of 49,000 pounds being continued by the jamming of the shot for an unusual length of time, burst the gun. Q. Is it your opinion that the explosion of a sfyell just within the muz- zle of a gun would rupture it? A. It would depend entirely upon the circumstances of the bursting of the shell and the strength of the gun at thaj point; the tendency would be to unduly increase the strain upon the gun ; it might or might not break it. Q. Do you think that a gun strained at one fire by a pressure to nearly the breaking point, will burst with a less pressure at a subsequent fire? A. Yes ; continued firing with a less pressure will burst it, and it may be at a very few rounds. Q. Then the fact that a gun may endure great pressure at one fire is no indication that it will endure a subsequent fire ? A. No; and hence it is that we have abandoned the old method of proving with double charges. A gun has so much work or endurance in it; it wears out, like anything else. Q. Why have no experiments been made to ascertain the exact effect of such casualties upon the guns ? A. I cannot give any other reason than that there has -not been time for it as yet. That is owing to obstacles of one nature or another interven- ing to prevent it. There has been much done towards perfecting ord- nance, and there is still much to do. Q. Have you ever estimated the amount of work exerted on the entire bore of a gun, with a tendency to rupture it, for each degree the bore is increased in temperature ? A. No ; I have not. Q. If the force of the powder alone was nearly sufficient to burst the gun, would not the addition of a small amount of expansive force be enough to rupture it ? A. It might do so if the initial strain on the gun was too great, but would not do so where the initial strain is too small ; the expansion of the interior of the gun from heat in firing being advantageous to guns having too little initial strain, and injurious to those having too much ; and the expansion of the interior, due to the heat from firing, should be taken into the account in fixing the initial strain upon the gun, and a margin left for its action that is, the initial strain should be so great as to bring the interior and the exterior to the breaking point simultaneously under the addition of external strain that should be imparted by heating the interior in firing the gun. Q. What is the greatest endurance, by number of rounds, any 8-inch Rodman rifles have endured ? A. But two 8-inch Rodman rifles have been fired to extremity ; the best one endured 1,047 and the other, I believe, 80 rounds the latter being fired with grooved projectiles. Q. Do you know anything about the endurance of the Ames gun, EXPERIMENTS ON HEAVY ORDNANCE. * 87 made of wrought iron, as compared with the 8-inch Rodman, as relates to the average amount of work stored up in projectiles of each from an equal number of the best examples of each kind of gun ? A. A 7-inch wrought-iron gun made by Mr. Ames, was fired, I think, about 700 rounds as a 7-inch gun, and was then reamed out to 8 inches, and fired 24 rounds as an 8-inch gun, when it burst. Q. Was that the best example of the Ames system of guns, as to endurance ? A. Yes ; of 14 other gu,ns (7-inch) offered, two burst in the proof, one at the first and the other at the eighth round. Q. Is that the one fired at Bridgeport? A. Yes ; the one that burst at the 724th fire is. Q. What was the size of the charges ? A. I do not know the size of the charges. I have examined the frac- ture of this gun. I folind two or three quite deep fissures on the interior of the bore; and that on the fractured surface, which was transverse, the breech blowing off, there was a surface, I should say, four inches wide and 12 to 16 inches long, in which the weld was so slight as not to amount to a weld at all. Q. I see by a report that a board of officers have recommended the purchase of 10 20-inch guns, 190 15-inch, 600 13-inch guns, all smooth-bore; 200 12-inch, 610 10-inch guns, rifles, for the armament of the fortifica- tions, which requisition has been approved by the Chief of Ordnance. Do you think that past experience with guns of these calibres, either rifles or smooth-bores, warrants the purchase of them for use in forts or on ship-board without further and more thorough experiments, and without the discovery of some means to make their endurance more reliable ? A. My impression is that the Chief of Ordnance did not approve the requisition as to heavy rifle guns referred to in your question. It is a question of public econcmy as to whether a nation should arm with cast- iron guns, known to be reliable for a certain number of rounds., or go to the expense of building up guns, or making steel guns that might stand a greater number of rounds. My belief is that for the present our cast- iron guns will do a given amount of service for less money than any other gun you can get; for rifle guns, I do not know that cast iron will so com- pare with steel guns or with built-up guns, as made in England, as to justify their adoption without further trial. My belief is that no nation has yet decided definitely upon what is the best material for rifle guns, taking into account their cost as compared with others. Experimental rifle guns have been recommended by the ordnance board and approved by the Chief of Ordnance, and, I believe, by the Secretary of War. It is contemplated that experiments with them shall be made before the pur- chase of any large number of rifle guns for service, and the Chief of Ord- nance so recommended in his annual report of 1867. Q. Do you intend to say that the experiments with Eodman guns, both smooth-bore and rifle, in service and in experimental firing, has demon- strated with any certainty what endurances can be predicted for any given gun ? A. I do. Q. Could you now predict a certain endurance for the 12-inch gun recently fired at Fort Delaware ! A. I could not, for the reason that I know that that gun has been unduly strained, and I do not know to what extent. Q. I mean only, in speaking of predicting a certainty of endurance, that all contingencies to accidents liable to occur shall be taken into consideration I 88 * EXPEEIMENTS ON HEAVY ORDNANCE. A. My belief is that after we shall have procured a projectile that is as certain in its operation in the rifle gun as the round shot is in the smooth-bore, that we can, by firing to extremity one or two 12-inch guns, fix a limit within which the gun may be considered as absolutely safe, but it will require experiment to fix that limit. Q. Why do guns of smaller calibre have so much greater endurance than guns of larger calibre ? A. For the reason that the pressure of gas upon them is less per square inch. , Q. Do you not increase the strength of the gun in proportion to the increase in the pressure of the gas I A. No ; it is not expedient to do so. We adopted a different course to meet this difficulty ; we used a slower burning powder, which should give a less maximum strain upon the gun, and a greater terminal strain than could be obtained with quick burning powder ; and increase the length of the bore of the large guns, so that under the more uniform action of the gas over a longer distance, and during a longer space of time, we impart to the projectile velocities nearly if not equal to those obtained in smaller guns, with powder heretofore used in them; and, in fact, we now secure greater velocities from a 15-inch gun than we for- merly did from 10-inch. Q. If the restraining force in a large gun is increased in proportion to the increase of force to be restrained, as your reply would indicate, then why is the large more liable to break than the small one! A. With the charge and kind of powder that we use in a large gun, I do not think it is more likely to break, other things being equal. It is more difficult to get a perfectly safe projectile for a large gun than for a small one. Q. Could you not so increase the thickness of the walls of the gun, and thus increase its restraining power, as to allow for the jamming or friction of the projectile ? A. I have no doubt that that might be done to a greater or less extent, by the hollow mode of cooling. A 10-inch gun, two calibres thick, cast solid, will not, in my opinion, be as strong as a gun one calibre thick, owing to the adverse initial strain imparted to it from the external cooling. Q. Do you assign any other cause for rupturing of guns besides the premature explosion of shells and the wedging of projectiles ? A. I do not think of any other, except a variation or want of regularity in the quality of the powder used, or the existence of adverse or im- proper initial strain in them. I regard the subject of powder as of equal importance in the endurance of guns with the strength of the gun itself. Q. Please read the following paragraph in the report of the Chief of Ordnance of the navy, as to the knowledge or lack of knowledge pos- sessed by the navy on the subject of ordnance, and say if any more knowledge is in your opinion possessed by the ordnance department of the army ? A. In my judgment, we do know that the main portion of our arma- ment of the forts ought to be smooth-bore guns, rather than rifles; the living force imparted to a shot by our largest smooth-bore guns cannot be with equal safety imparted to a rifle shot. The accuracy of 15-inch and 20-inch guns is, in my judgment, equal to that of any rifle we have at the distance of 2,000 yards, and that of 20-inch guns, especially, at greater distance. I think we do know that more reliable guns can be made of cast-iron than of wrought, intended to be in one piece, in the present state of the art of forging. I would also state, that if I were EXPERIMENTS ON HEAVY ORDNANCE. 89 going to remodel our heavy guns, I should make them heavier than they now are, our present model havdng been fixed in reference to the gun- carriages on hand for 10 inch guns; for 15 and 20-inch I should increase the weight, I think, certainly 25 per cent.; not only for the purpose of giving strength to the gun, but to diminish the injurious effects of the recoil upon the carriage and the platforms. I think experiments on powder, with a view to determine the best form in which to place it, ought to be made, as well as experiments continued on guns, for the pur- pose of determining the safe endurance of those we have on hand, and the proper material, models and forms of guns, for their respective projectiles. Q. In a report made by yourself in 1857, wTien a captain of ordnance, you make a statement in regard to important things connected with gun- making, of which you possess no positive knowledge. Have your subse- quent experiences thrown any light upon this question I A. They have. I have no doubt now that the strongest cast-iron, having the greatest elasticity, hardness, and extensibility, when cast into a gun, cooled from the interior, as they are now cooled, will make the best gun. I have no doubt either, now, as to whether guns should be cast solid or hollow, being satisfied that they should be cast hollow. I also feel satisfied that we know more about the proper model of a gun than we did at the time, that report was written ; we know better how to determine the model of a gun for a given weight of metal and diame- ter of bore. We do know with sufficient accuracy for practical purposes, the statical pressure due to a given wei'ght of powder and shot. We have also acquired knowledge as to the effect in endurance of the rapid appli- cation of charges exerting different degrees of strain upon the gun. We have also acquired knowledge as to the proper constitution of the charge to produce a given velocity of shot, with a minimum strain upon the gun. JANUARY 28, 1869. Bear-Admiral JOHN A. DAHLGREN sworn and examined. By the CHAIRMAN : 1. Question. State when you took charge of the Ordnance Bureau of the Navy Department. Answer. In April, 1861, the command of the navy yard at Washing- ton devolved upon me, all the other officers having deserted it. In July, 1862, I was directed to take command of the Bureau of Ordnance by the Secretary of the Navy. In July, 1863, I was assigned to the command of the South Atlantic blockading squadron. In June, 1865, I returned north, and the war of the rebellion being closed, I was detached from the squadron which I commanded. In December, 1866, 1 took command of the South Pacific squadron. In August, 1868, I was detached from the command of that squadron, and ordered by the department to take charge of the Bureau of Ordnance. 2. Q. Have you given especial attention to the subject of the fabrica- tion of guns ! A. I have; and I believe there are very few officers of our navy who have had as much experience as I have had. 3. Q. Are you the inventor of a system of gun-making, or the designer of a model for guns ? A. I am the inventor of a system of armament for our navy generally, including the guns and carriages to be used in it; also of a system of naval light artillery, including carriages and appliances. The character I 90 EXPERIMENTS ON HEAVY ORDNANCE. and some of the services of this ordnance may be noted from the opinions of distinguished officers immediately at hand, viz : Admiral Dupont says : But, besides this, I am impelled by a feeling of duty to address you. The large ordnance of this squadron has sprung from your inventive genius ; and thankful am I for one for those long years of study, scientific research and deductions which have so materially aided in arming the American navy as I believe no other navy is armed. Do you remember after I came from China my writing you how much I thought of the ^Minnesota's gun deck battery, (9-inches. ) In your reply you modestly seemed to think their days were numbered. I only now wish you could have seen the practice from this ship during the engagement, not alone for its precision and destructive results, but for the rapid- ity with which such large guns could be loaded with their heavy shell. I never get trans- portS, as the French term it, about such things, but I will repeat, to the day of my death, that the second assault of this ship upon the forts for rapidity, continuity, and precision of fire has not been surpassed in naval warfare. Extract from letter of November 24, 1861. Commodore Bodgers says : I saw the terrible effect of the Wabash battery at Port Royal ; it was so rapid in its fire that the rebels on shore reported in their papers that the Wabash was twice on fire ; it was merely the flames coming out from her batteries. I took a powerful spyglass and looked through it, and saw the shells falling at a rate that perfectly astonished me ; so that nothing could live there. The men were driven away from their guns. Testimony before, the Com- mittee on Conduct of the War Heavy Ordnance, p. 80. Assistant Secretary Fox says : The best shell-gun is Admiral Dahlgreii's nine and eleven-inch guns. Testimony before Committee on Conduct of the War Heavy Ordnance, p 170. Commodore Alden says : Question. What number and calibre of guns had you on board the Brooklyn in your expe- dition against Fort Fisher? -Answer. We had twenty 9-inch guns, two 10!J-po under Par- rotts, and two 60-pounder Parrotts all four of the Parrotts rifled. Q. How many times were those guns fired in the two attacks upon the fort? A. I threw into that fort 3,40..; nine-inch shells, over 120 tons. Q. How did the guns bear that shelling? A. As soon as I heard of the 100-pounder bursting, I put mine on the opposite side of the ship from that with which I was fighting, and put in their places the nine-inch guns, so that I had 12 nine-inch guns in battery all the time. Q. Then you did not use those 100-pounder Parrotts ? A. Not after I heard of the acci- dents with them on the other ships. I never fired them again. Q. Were those nine-inch guns made on the Rodman principle? A. They were Dahlgren guns. Q. Were they cast hollow or otherwise ? A. They were the Dahlgren nine-inch guns ; the best gun ever made. Q. What effect had that firing upon them ? A. I never discovered that any of them were injured. Q. Did none of them fail ? A. Not in the slightest degree. The men stand around them and fight with them with as much confidence as they drink their grog. * Testimony before the Committee on Conduct of the War Heavy Ordnance, p. 172. Captain Wise, Chief of Bureau of Ordnance, says : During the recent rebellion the cast-iron, smooth-bore guns of the navy endured all the severe service to which they were subjected, and proved their excellence everywhere and under all conditions of actual war. Not a single gun of the Dahlgren system has burst prematurely. * * * While the practice at the test battery against armor plating shows that even the 1 1-inch at close quarters is capable of piercing any thickness of iron or steel with which the sides of an ordinary cruiser, intended to keep the seas, could be covered with safety, and this without any danger of rupture from the use of increased charges, unless the gun has been very much weakened by previous service. * * * Annual report to Niivy Department, November, 1865. Vice- Admiral Porter says : The gun which I deem best adapted to general use in the navy is the 11-inch gun, which can be carried on board even our smallest vessels, worked in a sea way, if the vessels are properly constructed, and almost as rapidly as a 34-pounder; at all events rapidly enough for all practical purposes. I consider its accuracy much greater than any rifle gun, or any gun of a smaller calibre. That, I believe, has been tested to the satisfaction of most navy officers. EXPERIMENTS ON HEAVY ORDNANCE. 91 I remember once on an occasion having used 30 pounds of powder, when the service charge was only 15. You may remember that I drew the attention of the bureau to this at the time. Some thought that I was giving the gun more powder than it would stand. I recollect on the above occasion I attained great range, and prevented myself from being annoyed by some'rebel gunboats provided with small rifle guns of considemble range. See- ing the great range obtained with my 11-inch gun, they let me alone. I could not follow them, as there was a bar between us. ******** That most important power, ricochet firing, is entirely lost in the rifle guns ; and in a sea way a vessel armed with 11-inch guns is, in my opinion, a match for a vessel with twice the number of rifle guns. ******** I have never to my knowledge known an accident happen to the 9-inch, 10-inch, or 11-inch guns, three of the best guns we ever had in our navy ; and in battle men stand behind these guns in perfect security, knowing that the chances of their bursting are very small. * *** * * * * Against wooden vessels nothing is equal to 11 inch guns, and I believe that a small and fast vessel that could choose her distance, carrying a couple of 1 Much guns, could damage seriously, if not drive off, the largest ship in the British navy armed as they were in 1861. I believe, moreover, that an 11-inch gun, firing a solid steel ball, would smash in the Bides of some of the heaviest English iron clads, and would damage very seriously the turrets of some of our heaviest vessels Extract from letter, January 15, 1SG9. 4. Q. What is the method of the fabrication of a gun of large calibre in your system? A. The largest calibre which I proposed to use in wooden vessels is the 11-inch gun. At that time there were no iron-clads in existence. The casting of the gun was to be solid nearly of equal diameters, and tapering from the breech to the chase, nearly the diameter of the gun at the breech, but very much smaller than the diameters of the finished gun at the chase; the object being to produce as much uniformity in cooling as is desired. This casting was afterwards to be turned down to the dimensions required for the gun, preferring to leave the skin of the cast- ing on the cylinder and the breech of the gun, which, however, was not always done. 5. Q. From your experience, what do you consider to be the relative endurance of guns cast solid, of the model described, as compared with guns cast hollow, on the system of General Eodman 1 ? A. We have the practical results of a large number of guns cast for the navy in the way that 1 have described smooth-bores of 9 and 11- inch calibre; they have withstood all the tests of battle during the war of the rebellion, 1 believe, with hardly an exception. These cannon have done all the service that was required of them; were used in almost all our actions ; in the great battles of Dupont, Farragut, Porter, &c. Many of the 11-inch have been frequently fired with charges very much above those designed for them, viz, 15 pounds, which is all that was really necessary for eifect against the strongest wooden vessel. Being suddenly brought into the war of the rebellion, and being compelled to use these guns against iron plating, heavier charges were frequently resorted to. I may refer to the action at Mobile, where Admiral Far- ragut hauled up alongside the rebel ram Tennessee; he used much heavier than the ordinary charges. I have myself fired 11-inch guns in experimenting at iron plating with solid shot and 30 pounds of powder, which w^as mo?e than double the strain that the gun was intended to stand. One of them was fired in this way about 200 times and did not burst. I think, therefore, that it can be said that the form of my guns and the method of casting them are fully equal to every requirement of the severest service. The history of the past shows no endurance of other cannon equal to that of the 9 and 11-inch guns. Nothing has been more common in the great naval actions of the European naval powers 92 EXPERIMENTS ON HEAVY ORDNANCE. than the bursting of cannon and the loss of life consequent thereon. The records of our own navy are not without such accidents. In the celebrated fight of Paul Jones with the British frigate Serapis, some of his lower deck guns burst, " bio wing up the deck above and killing or wounding a large proportion of the people that were stationed below. This disaster caused all the guns to be instantly deserted, for the men had no longer confidence in their metal. It at once reduced the broadside of the Richard to about a third less than that of her opponent, not to include the disadvantage of the manner in which the force that remained was distributed amon g light guns. In short, the combat was now between a 12-pounder and anl8-pounder frigate." Cooper's Naval History, p. 106. I have no doubt that the same method of casting and fabricating the 9 and ll-inoh guns could be used in making the largest calibres; but to do so it will be necessary to obtain a competent knowledge of the kinds of iron that are to be used in the foundries for this purpose. 6. Q. Have smoothbore guns cast upon your system, with like charges, manifested greater endurance and serviceability than guns of like calibre cast according to the system of General Eodman ? A. I believe that guns of 8 and 10-inch calibres as well as of 15-inch have been cast hollow upon the plan of General Eodman, but they have never been proved to the extent that solid-cast guns of 11-inch calibre have been proved ; therefore, we do not positively know how great their endurance really is. The endurance of a few guns cast with special care under the superintendence of General Eodman is not to my mind complete evidence of the endurance of a large number of guns of the same kind cast at different foundries and taking the chances of the expe- rience or want of experience of different founders and of various kinds of iron. 7. Q. If you were now to re-arm the navy would you do so with guns cast solid or hollow ? A. If the guns were to be 11-inch, or of that weight, say 16,000 to 20,000 pounds, most certainly they should be cast solid, as they have always been ; if above that weight, then I should proceed to experiment with different kinds of iron, in the full belief that I should be as success- ful with these heavy guns as with the 11-inch. The first trials of cast- ing hollow guns of heavy calibre, by General Eodman, took place in 1849 and 1851. Six guns were cast, three hollow and three solid, in pairs. Each hollow-cast gun endured a larger number of rounds than its fellow cast solid. In all cases the solid guns were so bad that the comparison only proves that two of the hollow-cast guns were better than very bad guns that had been cast solid. Considering the hollow- cast guns by themselves, it will be seen that two out of the three were bad almost as bad as they could be, their endurance being so low. Only one of the three proved to be a good gun ; it withstood 1,500 rounds, and was not burst ; but every ordnance officer knows that it is not the excessive endurance of one, or of a few pieces, that gives character and confidence to a lot of guns 5 it is the uniform endurance of the whole, even if that be not very high ; because it is the unforeseen bursting of the gun that does the mischief in action. When General Eodman's hol- low-cast guns did attain a good degree of uniformity it was with an entirely different model ; and that model I claim as my own, and have f so apprised the War Department. With this new model General Eod- man made two 10-inch guns, putting them to an extreme proof, which they endured to the extent of 4,082 rounds without bursting. The solid gun was more indented at the seat of the shot than the hollow gun ; but I think this to be of little consequence, because, in practice, a gun of EXPERIMENTS ON HEAVY ORDNANCE. 93 heavy calibre would be laid aside long before it reached 4,000 rounds. I think the conclusions from these data are : 1st. That when the hollow casting was used with the columbiad of old model it failed to make them uniformly good. 2d. When the columbiad was shaped after my model the guns were as good when cast solid as hollow. I think the whole question of rifled guns is open ; I do not think that anything is known about it, either in wrought or cast iron. I know of nothing in foreign countries in which I believe they have really reached better results than we have here. But a few days since I observed in the newspapers that one of the English guns that they had relied on so much had given way, (the Fraser gun.) 8. Q. Have experiments in this country demonstrated, as yet, that large rifle guns can be made according to the Rodman system with a reasonable certainty of endurance ? A. I think not. 9. Q. How will it compare in rifles with the solid mode of casting? A. The solid casting has given no better results with rifled cannon than the hollow. 10. Q. What is your opinion as to the correctness of the Eodnian theory of gun-making ? A. At first sight it seems to be well founded ; but I think that a full consideration would show that it is quite as open to objection as any other, and even more so. Some of my opinions on this subject will be found more at length in a paper annnexed, marked note A. 11. Q. Has this system ever been adopted in the navy ? A. Only in the casting of 15-inch guns. That was done under very peculiar circumstances. The Navy Department had ordered 15-inch guns to be put into the first monitors. At that time we had no iron-clads, and the rebels had suddenly precipitated one upon our blockading squadron at Hampton roads, destroyed two frigates, threatened to break up the blockade there, and the plan of the campaign which was just about to move under General McClellan down the Chesapeake against Eichmond. The rebels were known to have iron-clads in readiness at other places. There was no time for experimenting with the 15-inch cannon ; it only remained for us to do the best we could. There had been but one gun of the kind made at that time; it had been cast hollow, and had endured a proof of about 500 fires, but with inferior charges; when, therefore, I sent the draught for the navy 15-inch gun to the bureau, I advised the bureau to have those guns made exactly as the first 15-inch gun had been .made, the hollow casting included, until there was time for experi- ments w T ith other methods. 12. Q. With what description of guns is the navy now provided; that is, as to methods of manufacture? A. The heavy guns of the navy are the smooth 9, 10, 11-inch guns, all of my own system, and cast solid; the navy 15-inch, cast hollow, and the Parrott 100-pounder rifle cannon. The 150-pounders have been with- drawn from the naval service. (See note B.) 13. Q. Have you any other rifled guns besides the 100-pounder Parrotts 1 A. No other. Opinion has very much changed in our navy since the beginning of the war of the rebellion as regards the value of rifled guns. Then the demand was incessant. The idea seemed to be prevalent that smooth-bore cannon could not be pitted against rifle cannon under any circumstances. I think that sentiment is very much changed. My own experience, from repeated action, induces me to give preference to heavy smooth-bore guns. I always thought that they hurt our iron-clads more 94 EXPERIMENTS ON HEAVY ORDNANCE. in battle than the rifles did, and I am inclined to believe that the same opinion prevails largely in the navy, independently of the distrust of the rifle guns which we now have. 14. Q. Have not these changes in the views entertained in the navy with respect to rifles been largely owing to their unreliability f A. I think they have ; but independently of this I have seen instances where the power of the 11-inch and the rifled 150-pounder were in direct contrast. A number of officers and men witnessed the practice at long range of both. 1 allude more particularly to a case in battering a work on the Stono river. 15. Q. Were not the Parrott rifles condemned by the board of ordnance officers u ? A. The 150-pounders were recommended to be withdrawn by a board, which was done. The bureau also reduced the charge of the 100-pounder. (See Report of Bureau, 1865.) 16. Q. If the condemnation extended to all guns made by Captain Parrott, why have they been retained in service f A. It did not extend to 100-pounders or to rifled guns of less calibre. 17. Q. Do you think the 100-pounders reliable guns I A. I should be apt to handle them very carefully. 18. Q, Have any Parrott guns burst in the naval service since the conclusion 'of the war ? A. Yes ; a rifled 30 pounder burst recently in the South Pacific squad- ron, which I just left. I do not think the number of rounds had amounted to 200. I reported it to the Secretary of the Navy, and told him we had no rifle guns in the navy that were reliable,* asking leave to pro- ceed to investigate the question and ascertain if reliable rifle guns could be procured. 19 Q. What is your opinion of the utility of guns as large as those of 15 and 20-inch calibre, as compared with smaller calibres ! A. I was not of the opinion that the 15-inch gun was most suitable for the navy. I doubted if sufficient charges could be used to drive a shot of that size with the required velocity, having proper regard, first, to the endurance of the gun, and then to the endurance of the carriage. It is considered advisable to check the recoil by mechanical means ; and it is doubtful if they would long endure the enormous strain of very heavy charges. A lower calibre than 15-inch, with a higher charge, might be sufficiently effective against iron-plating. I was conducting experiments to that end in 1863, when I left to go to sea, and had driven a 10-inch shot through six inches of iron at 200 yards, with a smooth- bore of 10 inch calibre. 20. Q. How does rapidity of fire, other conditions being equal, affect the result of battles, ship against ship, or ship against works on the shore ? A. Of course the more rapidly that successive blows could be struck the sooner will the result be reached ; but the safety of the gun is to be considered, as the bursting of a 15-inch gun on board of a ship would be very fatal. 21. Q. What is the heaviest calibre of gun compatible with rapidity of fire and mounting, in numbers, 011 the broadside of ships I A. In my system of naval armament I take the ground that the heaviest guns should be used which can be worked upon the broadside carriages, and for pivot guns that throw the heaviest shot that can be handled at sea ; the rapidity of fire of such cannon is quite sufficient * This does not include our rifle boat-guns, which are good enough. EXPERIMENTS ON HEAVY ORDNANCE. 95 under the most favorable circumstances, the gun not being trained or pointed, nor the elevation changed. An 11-iucli gun can be fired on a fixed platform once a minute ; but I doubt if this can be done on ship- board in action ; certainly not continued for much time. 22. Q. How rapidly are 15-inch guns in monitor turrets fired ? A. My recollection of that is not very clear ; in action there were always other objects to take off my attention $ but so far as I do remem- ber I think it required between five and six minutes to fire a shot j that, however, included the revolution of the turret from the enemy's battery and back again. Moreover, the person who fired the gun could never see the object, but was directed in his aim by another person at a tube in the side of the turret. Then there was time lost by giving the word to the engineer, who worked the lever for turning the turret ; all this and the swaying of the vessel must be counted in the time of firing. 23. Q. Are rifie or smooth-bore guns most effective against iron plat- ing, if the weight of the gun and projectile are alike, and the initial velocity is the same from both kinds of guns ? A. Supposing shot of equal weight to strike with equal velocity, 'I should prefer the round shot ; but this is open to opinion and further experiments. 24. Q. Have any experiments been made to ascertain the effect uon guns of the premature explosion of shells within their bores f A. I remember trying one such experiment with an 11-inch gun. 1 think it was evident in some cases that the shell was not burst in the bore of the gun, by arrangements that were made for the purpose. In the other cases the shell had burst in the gun. The gun was unhurt, but the number of rounds were small five or six. Still, I have a very strong doubt if the bursting of shells in guns are the cause of the repeated splittings of the chase that are reported. 25. Q. Do you attribute the rupture of guns to that cause if a gun gives way in the rear of the trunnions f A. If a cannon gives way in the rear of the trunnions it must be owing solely to its inability to withstand the charge with which the gun has been fired j but a gun might have such bad metal in front of the trunnions that it would crack from the bounding of the projectile in connection with the bursting of the shell. I have never seen a gun myself that I thought was split in the chase by the bursting of shells. 26. Q. How do you account for the blowing off of the muzzle in the 15-inch gun! A. If a gun had previously been cracked in the chase, the force of the charge and bounding of the projectile might subsequently be sufficient to break the chase and blow the pieces in front. 27. Q. Does increasing the thickness of the wall of the gun beyond a certain limit increase the strength of the gun f A. I think not. I think there is a thickness of metal, taken in con- nection with the process of founding, which will give a greater strength to a gun, within certain limits j of course a gun might be made so extra- ordinarily thick that no charge could burst it. 28. Q. Does the strongest iron always make the strongest gun ? A. There was an idea prevailed, when I first became connected with the ordnance, that the quality of iron for guns was invariably indicated by a certain degree of tensile strength and density, without reference to the different qualities of iron. To this I never agreed j and I am inclined to believe that the advocates of the theory are pretty well satisfied that it was not well founded. I, myself, have always used the tension strain and density as measures of uniformity simply j that is, when a good gun 96 EXPERIMENTS ON HEAVY ORDNANCE. had been obtained from any kind of iron, the tension strain and density of its metal, in connection with other signs, were to be followed in other guns of the same class cast from the same kind of iron. The kinds of iron differ very much, and hitherto we have been able to obtain good guns from all of them by varying the treatment. 29. Q. Are there any means of ascertaining, with approximate accu- racy, the pressure of the gases of gunpowder on the bore of a gun ? A. I do not think there are. General Kodman has a method which he relies on, and which, I believe, is confided in by the War Department. But I confess I never did rely upon it as entirely accurate. There were experiments tried for this purpose by Colonel Bomford, very many years ago, by boring a hole along the line of a gun to measure the force with which the gases issued from these apertures. This idea has often been attributed to myself, and is said to have been the basis of the form which I have used for cannon ; which is eKtirely incorrect. The idea belongs to Colonel Bomford, and the form of my cannon are the results of reasoning entirely. The draught of the first 11-inch gun is the same that is now used. I never altered it in any respect, except to remove the swell of the muzzle from the end of the gun, for more convenient use in the narrow ports of iron dads. 30. Q. Is the range for an 11-inch gun, with light charge, so nearly uniform as to justify the belief that the pressure of the gases of the powder is nearly uniform in the gun $ A. I have no means of answering this question positively. The ranges of the 11-inch guns, with the regulation charge of 15 pounds, are very uniform, and I think more accurate than any other smooth-bore gun of the same description and calibre. 31. Q. Have you ever determined, by experiment, the ratio of increase of the pressure of gasses of powder in a gun, if the weight of the pro- jectile is increased 1 ? A. I never have, nor do I think there are any means by which that could be ascertained. We know, generally, that the pressure upon a gun increases in a much higher ratio than the weight of the charge of the pow- der j that is to to say, if you double the weight of the charge you would very much more than double the strain upon the same gun. 32. Q. Would the pressure of the gas evolved from the powder upon a square inch of the surface in a chamber of the same diameter be less or greater than the pressure per square inch in a large chamber ? A. I do not think that we have any means of determining these results with any accuracy. 33. Q. Have any experiments been made to determine the increase of strain upon the* bore of a gun by not having the shot home against the powder charge ? A. I think, many years ago, that Commodore Stockton made some experiments of that kind. The general impression is that there should be no space between the charge and the shot, as it strains the gun more. 34. Q. Do you know the comparative tensile strength and density of the iron used in the long 68-pounder and the Dahlgren 9-inch gun $ A. 1 do not 5 but believe that the metal of the English 68-pounders has always been inferior to that of our 9 and 11-inch guns. 35. Q. It is stated that the tensile strength of the long 68-pounder is about 18,000 pounds, while that of the 9-inch gun is 30,000. A. The tensile strength of the United States guns varies with different irons. We have had excellent iron where the tenacity was 25,000 pounds, while the West Point and Boston iron was giving good metal at 30,000 to 35,000 pounds; but the English establishment failed so badly with EXPERIMENTS ON HEAVY ORDNANCE. 97 their 68-pounders that it was thought to have been one of the causes that led to the substitution of a scientific civilian like Sir William Armstrong for the officer in charge of the government foundry, a measure which worked badly in all respects, particularly in cost. 36. Q. What is the least tensile strength permitted to be used in the 11-inch Dahlgren guns? A. That would depend entirely upon the tenacity exhibited by a good trial gun. If such a gun were made at Boston, the iron they use would probably exhibit a higher strength, elsewhere a lower. I had some diffi- culty in that respect with some of the 15-inch guns that were made at Pittsburg, and had a correspondence with the founder on that subject he having varied considerably from the density of the trial gun, which I insisted he should adhere to within certain limits in order to preserve uniformity with the trial gun. 37. Q. Do you think the tensile strength of the iron has comparatively little to do with the endurance of the gun ? A. It is necessary to maintain it in that degree, which is ascertained by trial to belong to the kind of iron used. 38. Q. How do you account for the apparent anomaly referred to in Eodinan's book, where he says the strongest iron does not make the strongest gun, and where he states that having too much density resulted in reducing the endurance of the gun? A. The iron of the highest density does not always make the strongest gun. 39. Q. Will the charge now prescribed for the navy gun give the highest attainable velocity to the shots ? A. The regular charges for the 9-inch and 11-inch guns will give all the velocity required to do the work for which these guns were designed; that is, the destruction of wooden vessels. They will bear much higher charges I should say one-half higher ; and there is an order at the bureau authorizing 30 pounds to be used with the 11-inch guns in special cases. 40. Q. Will they bear 50 pounds of powder? A. The carriages would not very long, and it is not necessary that the guns should, for the purposes for which they were made. 41. Q. Will they endure the charges necessary to give the highest velocity to the projectile ? A. The 11-inch can be safely used as high as 25 pounds, and even to 30 pounds, which is double the charge for which the gun was designed. 42. Q. How do the highest charges successfully used in these guns compare with the charges successfully used in the Armstrong guns ? A. I am not sufficiently informed in regard to the Armstrong guns to answer accurately ; but we do know that the Armstrong guns have been laid aside, and that the 9-inch and 11-inch guns are not. 43. Q. You have said that a 100-pounder is the only rifle cannon in the United States naval service ; what is its ability to stand heavy charges, compared with other rifles? A. I am unable to say. 44. Q. What is your opinion of the Ames system of making wrought- iron guns? A. It must be judged by its results; they are before the committee. 45. Q. Do you think the Ames guns are better guns than Parrott's? A. Whatever may be said of the merits or demerits of the Parrott gun, or the necessity for superseding it, no other rifle gun has yet obtained sufficient confidence to take its place. Rep. No. 266 7 98 EXPERIMENTS ON HEAVY ORDNANCE. NOTE A. [Despatch No. 576. ] FLAG STEAMER PHILADELPHIA, Port Royal Harbor, #. (7., November 20, 1864. SIR : I have received but a few days since a communication from the Bureau of Ordnance in relation to the casting of cannon of my design. The nature of the recommendations therein made by the bureau to the department seems to render it proper that I should address the depart- ment directly. The unceasing demands on my time and attention absolutely render it impossible for me to reply to this communication as I would wish, nor have I the documents at hand, if I had the leisure to use them. I am, therefore, obliged to content myself with the following incomplete expression of my views : The 9-inch and 11-inch guns of my design have manifested all the en- durance that has been required through a course of trial on the proving ground, and through a course of service which has seldom, if ever, been applied to any other cannon. The endurance has never been approached previously by such heavy calibres, and it has also been uniform, which is absolutely indispensable to give value to any endurance, for it is the unexpected bursting of can- non that does the mischief. In trials made to test the strength of the 9-inch and 11-inch no gun has ever fallen short of 1,500 rounds when fired with the charges for which the cannon was intended, and I feel no doubt that if the firing had been continued with service charges, the guns tried would have gone to 2,000 or 2,500 rounds. This was never done, because no probable exigency would ever have made such a demand on a single gun 5 extreme charges were therefore substituted. Some of the cannon that have been so tested were at the Washington navy yard, and unless removed are there still. One of them, a 9-inch gun, was fired 1,500 times with service charges, and still looks well 5 another was fired 1,500 times, and then with increas- ing charges, until at the 22d of such fires there were 20 pounds of powder and 90 pounds of shot in the gun when it gave way. Many other cases of severe proof are recorded of the 9-inch guns. The first 11-inch gun was fired more than 1,300 times with shell, and about 650 times with solid shot of 170 pounds ; it burst at the 1,959th round fire. Other 11-inch guns have been submitted to severe tests. One was used for practice against iron plates with solid shot, and charges increasing to 30 pounds, to the extent of 200 fires, and was in good order when I left it. It is to be borne in mind that these guns were not intended to be fired with solid shot, and that previous to their advent 800 rounds were looked on as a fair standard for heavy guns, such as columbiads. In actual service the record of the 9-inch and 11-inch guns is unex- ceptionable. They have constituted the armament of our principal ships of war for 10 years. They have been carried over the whole globe during more peaceable times in those superb ships Wabash, Minnesota, &c., and now that rebellion and disloyalty threaten the Union, they are identified with the greatest glories of the flag. EXPERIMENTS ON HEAVY ORDNANCE. 99 Admiral Stringham, at Hatteras ; DuPont, at Port Royal j Farragut, at New Orleans and Mobile, illustrated their power against forts and batteries, while the Kearsarge vindicated the principles of my system generally against the matured conclusions of British authorities. Hundreds of these guns have been cast and carried by vessels second to none of their class ; in no one instance has a single 9-inch or 11-inch cannon been burst on shipboard or a man hurt. One or two were split at the extreme end near the muzzle, but this could only have arisen from improper loading, and the guns were still capable of being used with effect and safety. No officer hesitates to place confidence in his 9-inch or 11-inch guns, and Admiral Farragut when engaging the Tennessee shotted his 9-inch shell guns with one-third more powder than the usual charges, and he was not mistaken, at least in their endurance. These guns were, in the strictest sense, shell-guns. They were designed 15 years ago, when wooden vessels only wore to be the objects of fire, and it was this extensive application of the shell power that caused resort to iron plating to keep them out. But so great was the strength which 9 inch and 11-inch guns proved to have, that no hesitation existed in loading them with shot and higher charges of powder for battering even iron plating, and the 11-inch guns did good service to the country on more than one such occasion. When the rebel rani Merrimack issued forth and inflicted such griev- ous damage at Hampton Eoads, she was driven back by the Monitor's two 11-inch guns, and never ventured on another trial. There was a deal of wise discussion at the time about penetration and wrought-iron shot, &c. ; but the simple and undisputed fact remained. The Merrimac was obliged to endure the blockade of the Monitor, and never dared to venture to the conflict 5 her commander preferred to sink her, and did so. At Mobile the few brief moments of opportunity were so aptly used by the rapid fire of the 11-inch guns of the Chickasaw that the iron- clad Tennessee yielded to their blows, when neither the tremendous shocks of the steamers nor the sluggish fire of the 15-inch gun had been able to accomplish the desired result. In the end they might have done so, but in battle, time is just as essential to success as in other things. Here it is notorious that the rapid and sustained fire of the 11- inch cannon of the Ironsides was more dreaded by the rebels than the 15-inch guns of the monitors, and while she remained here attracted the chief efforts of the rebels to blow her up. If, then, so many important and undisputed facts have established the endurance of these guns, while their origin, use, and association with events have imparted to them a reputation so entirely naval, why pro- pose any change in their manufacture ? They have faithfully withstood every ordeal, and are now identified with the fame of the navy in this great struggle of the country to main- tain its very existence. What public interest demands it, if all that has been proposed or required in the use of the guns has been accomplished ? Change of itself is not improvement, and it cannot in this instance be made without additional expense to the treasury. One cent per pound is seemingly no great expenditure, but in each gun itself it amounts to one, two, or even four hundred dollars, and when cannon must be made by hundreds the sum becomes important. But the recommendation is not merely to substitute hollow castings for solid, or to exercise a sound discretion at any time upon the subject, for the 15-inch guns of the navy designed by myself are cast hollow, 100 EXPERIMENTS ON HEAVY ORDNANCE. according to Major Eodman's plan of casting; the proposition is to use no other mode of casting but Major Eodman's, and to bind the bureau itself from using any other. Why do this"? Why voluntarily impose a restraint when none is needed? Is there any apprehension that the asserted superiority of the hollow casting might suffer from competition 1 ? No opinion is given in the documents of the bureau from Mr. Chaffee, the manager of the Providence Works; I should have liked to know his opinion ; and the letter of Seyfert and McManus is by no means a testimonial to the merits of the hollow castings. The paper of Mr. Parrott states many facts which are of interest, though they seem to have escaped the pencilled selection of some care- ful hand. I beg the particular attention of the Navy Department to one of these remarks. Mr. Parrot says : I was particularly acquainted with the manufacture and trial of the navy 9 and 11-inch Dahlgren guns, cast solid, and they had given more uniformly satisfactory results than the hollow-cast columbiads of the old model, to which the experiments of Major Rodman were for a long time confined. It did not appear from the foregoing and other trials that the very great theoretical advan- tages which might be hoped for in the hollow castings were particularly realized. (See Rodman on Metals for Casting, &c., 1861, pp. 94, 96, for statements of these advantages.) But a further experiment was made after the model of the 10-inch columbiad had been changed, by rounding off the angular breech and giving increased thickness at the bottom of the bore. In this instance both the solid and hollow-cast guns endured well, reaching 4,250 rounds each without bursting. I think that what Mr. Parrot here states admits of neither question nor qualification. Please to note that the solid-cast 11-inch gun, not with any special care, but with no more than is usual in current manu- facture of a large number, gave "more uniformly satisfactory results than the hollow-cast columbiads of old model to which the experiments of Major Kodman were for a long time confined." Now note what Mr. Parrot says a little further on : But a further experiment was made after the model of the 10-inch columbiad had been changed by rounding off the angular breech, and giving increased thickness at the bottom of the bore. In this instance both solid and hollow-cast guns endured well, reaching 4,250 rounds each without bursting. The plain and direct conclusions from these statements are : 1st. That when Major Eodman's mode of hollow casting was applied to the army columbiad of the old model my solid-cast 11-inch guns gave more uniformly satisfactory results. 2d. And that when the model was changed there was obtained a very striking advantage to Major Eodman's hollow casting. It went to 4,250 rounds. This would have been a stubborn fact to overcome by itself, but it does not stand by itself; for a gun of exactly the same improved model was cast from the same furnace, the same iron, and cast solid, as the \\.-inch guns are cast. That, too, endured just the same amount of firing as the hollow- cast, nearly 4,250 rounds. Well, from all this it follows: 1st. That hollow casting would not save a bad model. 2d. That when the bad model was changed to a better, the solid-cast gun endured just a:u much as the hollow. Now I desire that the department may be fully aware of what is implied by this "rounding off the angular breech and giving increased thickness to the bottom of the bore ; " and to do this I would ask that three models may be made and placed before you, having the diameters at the base ring equal in all three models. No. 1 shall be a 10-inch col- EXPERIMENTS ON HEAVY ORDNANCE. 101 ulnbiad of the old pattern, that even Major Bodman's hollow castings would not save, and which he has abandoned. No. 2 shall be a 10-inch columbiad of the pattern to which it was changed and which is now used, having given so much endurance to the hollow and solid castings. No. 3 shall be that of my 11-inch gun. Let the eye then decide how far the model of the 11-inch gun departs from that of the old columbiad or any previous model, naval or mili- tary; and how marked the coincidence of the new army 10-inch and 15- inch with the model of the 11-inch, the latter being rather longer ; but in the disposition of the metal about the vital parts of the gun, how close the resemblance. The appendage for elevating being a plate in one gun and a cascabel in the other; but neither affects the principle of construction that disposes the mass of metal about the bore. My guns are chambered, and the army guns are not, which has no connection with external model, but concerns the bore alone. The eye cannot be misled by any special arguments developed in lengthy technical formula and symbols entirely incomprehensible save to the initiated few. To it the relative diameters at different parts, the character of the curves that unite them, the absence of projections and rings, produce forms as nearly identical as possible to vary at all. The department has already the statements of Mr. Parrott that the mode of hollow casting did not succeed with the old model, but that it had suc- ceeded with a new model ; and I think it will appear from comparison of the models just suggested that the model of the army 10-inch and 8-inch, as well as the 15-inch, made by Major Rodman, is identical with the models of my 9-inch and 11-inch guns. This I submitted to the War Department some two years ago, and so far all I gained by a plain statement has been some long arguments by Major Eodman, in which he undertakes to show that the models are not alike, as if any statement could possibly negative the plain evidence of one's sight. So that the change to the hollow casting did not succeed until a change of model was resorted to, and this was an adoption, in effect, of the 11-inch model. It is now attempted by the recommendation of the bureau to take from me even the claim to the hard labor of years. Such a wrong as this I feel assured will not be tolerated by the department. It has caused me the greatest astonishment, coming as it does from the naval Bureau of Ordnance, to which I might have looked for at least fair play. My absence and present duties might have plead for postponement at least, no necessity being shown for such urgent action. But if the recom- mendation must be made, why not a few weeks earlier than it was f I was in Washington, and might have said a word in my own behalf. Why defer until some three weeks after I left, a proposition involving so much to myself, and then urge it upon the department, leaving me after- wards in utter ignorance of what was going on, until the department insists on knowing what I have to say I Nothing but the consideration of the Navy Department averted the decision. With a wise and sound discretion it refused to act hastily, and until I had been heard. I cannot admit that we yet know all that is needed to a full decision as to the mode of casting. If hollow casting is better for any size of guns, why cool it with water 1 Will not the old mode of casting hollow, as practiced a century, answer ? Who can speak of trials made with American material, such as now used, and American experience ? Mr. Chaffee had the boldness to cast a 13-inch gun solid, and it endured 172 firings ; this was considered a failure. 102 EXPERIMENTS ON HEAVY ORDNANCE. When the largest of these hollow-cast columbiads gave way with per- haps no better endurance, was that considered a failure ? Mr. Chaffee had never cast so large a gun ; he had never melted and cooled the iron he used in such great masses ; if he reached the result he did at the first trial, what might be expected by further experience f My own impression is that this result was, under the circumstances, highly favorable. In conclusion, I hope that I have been able to satisfy the department that there is every propriety in my submitting an earnest protest against the recommendations of the Bureau of Ordnance : 1. It is needless, because the 9-inch and 11-inch guns have done all that has or should be required of them without failing in any one instance. 2. It is an additional expense to the government without any advantage. 3. It is unjust to the hard and constant labor which I have given to the subject, and to the benefit which the navy has derived from these labors. 4. It is forbidden by professional regard for ordnance naval in its origin, naval in its use, and naval in its association with great results. I will only add my earnest request that the department will give an order to the Bureau of Ordnance that no change whatever shall be made in the model or details of my 9-inch and 11-inch guns, and that they shall continue to be cast and finished just as they have been that is, solid ; and that no change shall be made in the model or details of my new 130-pounder (10-inch) and 13-inch guns. I believe it is supposed by some that considerable pecuniary advantage results to me from these guns. I have only to say that I never derived a cent from them, nor asked for it. I have the honor to be, very respectfully, your obedient servant. J. A. DAHLGREN, Rear-Admiral, Contfdg South Atlantic Blockading Squadron. Hon. GIDEON WELLES, Secretary of the Navy. NOTE B. [From the " Ordnance Instructions," United States navy, 1866, page 102, part /.] Owing to the recent accidents which have taken place with these guns the ISO-pounder has been withdrawn from service, and the charge of the 100-pounders provisionally reduced to 8 pounds of rifle powder, and the short shell of 80 pounds only is to be used. JANUARY 29, 1869. NORMAN WIARD recalled. By the CHAIRMAN : 1. Question. What are the most important qualities of the metals fitting them to be the material from which guns are to be made ? Answer. Tensile strength, i. e., ability to resist ultimate pressure or ability to resist breaking apart against the extending strain. Permanent elasticity is next in importance, which is, in fact, the ability to recover the original form and dimensions after the distorting force has ceased to act. Incompressibility is another important quality, involving hardness to resist penetration or abrasion. Ductility is a quality not desired in gun metals, as it is seldom accompanied by elasticity. The qualities of metals as conductors or non-conductors of heat should be considered, as EXPERIMENTS ON HEAVY ORDNANCE. 103 the metal for large guns which will conduct the heat slowest from the surface of the bore outward when being fired would be most unequally heated, other conditions being equal. 2. Q. What direct forces act upon the bore of the gun, having the tend- ency to deteriorate it or destroy it ? A. The elastic force resulting from the combustion of gunpowder should be divided and considered in both of its forms, namely : pressure that is inert without motion, but which is exerted in all directions equally, requiring a definite strength to resist its performance of work, and projectile force, or vis viva, a quality of force resulting from the ele- ments of pressure and velocity, pressure and distance, or pressure and time of action while in motion. 3. Q. When a chamber is filled with gunpowder and the powder is ignited, which of these forces act upon its surface ? A. If a chamber be filled with grains of powder, and each grain be ignited simultaneously, the gas resulting from combustion would flow radially in all directions from each grain as a centre ; the currents meet- ing half way between contiguous grains would expend nearly all their pro- jectile force and motion upon each other, resulting in a pressure against the walls of the chamber, but slightly greater upon each square inch of the sur- face, than would result in the same chamber if the grains had been inserted one at a time in succession and ignited, with the gas confined until the same quantity of powder had been burned. If the chamber were spherical and only half filled with powder grains, upon the ignition as before, part of the powder and gases would be projected across the vacant space in such various directions that a large part of the projectile force would be expended by the diverging, converging, and reverberating currents, upon each other. The effect upon the walls of the chamber on the unfilled side would be, however, greater than in the previous case referred to with the chamber full, though depending principally upon the rapidity of com- bustion. If the chamber contained the proper quantity of water to be evaporated into steam, and which created the same ultimate pressure in the chamber, to be generated by slowly heating the water, it is obvious the rate of its projectile force against the walls of the chamber would but slightly exceed the forces of ultimate pressure. If the Kodman instrument. Plates VIII and IX, relied upon by the ordnance corps for the determination of the pressure of powder in guns, should be inserted in the side of the chamber while the pressure of the steam was gradually evolved, the cut in the copper specimen would have the same depth as any other cut in any other specimen made by the application of a weight equal to the pressure, in pounds, of the steam against the piston of the instrument. But if the Eodman instrument should be applied to the chamber upon the outer end of a tube seven inches in length, having a stop-valve closed while the steam was being generated to the pressure of 5,000 pounds to the square inch, when the valve was opened the steam would flow along the tube with such velocity as to strike the piston of the instrument with a projectile force, which would cause a penetration of the copper specimen so deep as to represent a force of 15,850 pounds. If the length of the tube should be increased from seven inches to nine inches, the projectile force would be equal to a pressure on the piston of 21,100 pounds, and with 11-inch length of tube, the pressure would be equal to 27,800 pounds upon the square inch. These statements and figures are founded upon the experiments of Eodman, as shown on page 197 of his book, (see Appendix D, miscellaneous extracts,) the result of the firing guns, each having a different thickness of wall, namely, a 7 inch gun with a wall about seven inches thick at the front of the cartridge ; a 104 EXPERIMENTS ON HEAVY ORDNANCE. 9-inch gun with a 9-inch wall, and an 11-inch gun with an 11-inch wall. If it was pressure of the powder in this case which caused the velocity to be given to the projectile, it is most remarkable that the velocity of the shots for a mean of 10 fires from the 7-inch gun, in which the powder exerted a mean pressure, according to the indications of the instrument, of 12,675 pounds to the inch, should be so nearly the same as the velocity of the projectile from the 11-inch gun, in which the instrument shows the mean pressure to have been 36,224 pounds to the square inch, or nearly three times to force "behind an equal column of metal.'*' (The table of the results referred to is shown, Appendix D.) 4. Q. Then you have the opinion that the Rodman instrument only shows the projectile force of the powder, and not its pressure ? A. The deductions drawn by Rodman in relation to the pressure exerted by the powder upon the surface of the bore of the guns are very lame conclusions, yet they have been taken as indicating a proper model for guns to give "the required strength at the different points of their length, and as confirming the fallacious conclusions of the ordnance corps, founded upon the experiments of Colonel Bomford many years ago, having for their object the determination of the pressure at the different parts of the length of the bore. Colonel Benton says of these experi- ments: "About 1845, Colonel Bomford devised a plan for determining the pressure at various points of the bore by conducting experiments that essentially consisted in boring a series of small holes through the side of the guns at right angles to its axis, the first hole being placed at the seat of the charges, and the others at intervals of one calibre ; a steel ball was projected from each hole in succession by the force of the charge acting through it, and the pressure at the various points was deduced from the velocities communicated to the balls.'" This, and the common use of the Rodman instrument in all late experiments by the ordnance corps, shows that it is only the projectile forces of the powder which has been considered by them from 1845 to the present time, and upon these falla- cious theories the models of our guns have been determined and their strength fixed. 5. Q. What is the difference between the projectile force and the pressure of the powder, and has one a fixed and continuous proportion to the other ? A. The projectile force of the powder is the force equal to that which would be developed or exhibited in stopping the projectile. The pressure is that force which gives it motion in the gun, and it can be seen that if such a force as that acting upon the projectile should act against the sur- face of the bore in the gun, no material could be found from which guns could be made which would not either enlarge the bore or burst as a gun, unless it were from material which, if formed into a plate and fixed upon the side of a ship as armor, would resist the impact of a shot from a gun without any indentation whatever. When a wrought-iron shot is fired from a gun at a plate which it does not penetrate to any considerable depth, the shot is flattened by the impact. If the pressure of the powder were not less than the projectile force, the shot would be invariably flat- tened to the same extent in the gun, which, however, is not the case. I have frequently experimented with an air-gun of one-fourth of an inch in diameter of bore. With a pressure of 750 pounds of air to the square inch in the receiver, the bullet is projected with force enough to pass through one inch thickness of hard wood. After charging the gun with that pressure, I have discharged a bullet from it and penetrated that thickness of wood ; then after inserting another bullet, have restrained it from being ejected from the barrel by inserting a steel ramrod down EXPERIMENTS ON HEAVY ORDNANCE. 105 against the bullet by the pressure which I could exert with my hand, grasping the ramrod where it protruded from the muzzle of the gun ; upon removing the ramrod the same bullet previously held in the gun was discharged and passed through the wood target. It is obvious that I could not have forced the ramrod through one inch of hard wood by any pressure that I exert by my hand under such circumstances. In fact, I found that I could scarcely make a perceptible indentation in the wood by a pressure on the ramrod equal to that which I had exerted while restraining the bullet in the gun. 6. Q. Are the indicated pressures shown by the Eodman instrument uniform under like circumstances 9 A. They are not ; on many occasions, with equal charge of powder and equal weight of projectile in the same gun, the results have been widely different they are quite as incongruous as would be the penetra- tion of a shot from the same gun projected against iron armor, if the shot should sometimes strike fair, and at various other times ricochet once, or ofteiier, from intervening ground between the gun and target or meet obstructions to its flight previous to hitting the plate. 7. Q. What is the cause of the uncertainty of the instrument? A. The currents of gas projected against the piston of the instrument are obstructed sometimes by the intervening grains of the unburnt pow- der. They may be reflected or diverted from the straight line of direction, thus expending their projectile force, or part of it, against other surfaces, in which case of course the instrument could not record the full projectile force. 8. Q. Is it only the projectile force of the gases of powder which causes the penetration of the specimen with the Eodman instrument ? A. No ; there is also the projectile force of the piston and moving parts of the instrument itself, (see figure 2, plate IX,) which adds greatly to the force as it is recorded, so that under no circumstances whatever could the instrument fail to show a force much greater than the direct pressure of the powder as exerted to enlarge the bore or burst the gun. So called pressures have been indicated by the instrument on the 15-inch gun with 55 pounds of powder, as low as 10,000 pounds to the square inch, and indications from 11,000 to 13,000 pounds are quite common in the reports ; it is quite impossible, considering the momentum of the piston and moving parts of the instrument, but that these lowest pressures are greater than the real pressure exerted by the gases of the powder on the gun under any circumstances. In one report I find a pressure as recorded of 13,000 pounds giving an initial velocity to the shot of 1,441 feet per second, and on another page of the same report another pressure of 98,000 pounds, in the same gun, giving only a velocity of 1,240 feet per second with an equal charge. 9. Q. Is it possible to avoid having the projectile force of the gases of the powder act upon the surface of the bore in the gun ? A. It is only necessary, in order to prevent the projectile force acting to an injurious extent, that the chamber should be full, whether the powder be coarse or fine, or whether it burns quick or slow ; the ultimate pressure would be nearly the same, if the powder is composed of the same elements equally incorporated. The projectile force with which the gases of the powder expand, if unrestrained even for a short length of time, is much greater for quick than for slow-burning powder. If the projectile should not be down against the cartridge, although the impact of the projectile force of the gases against the rear end of the shot would be greater than the pressure of the powder, the shot would not have so high a velocity communicated to it, because the time of the action of the 106 EXPERIMENTS ON HEAVY OKDNANCE. force against the shot would be less. Therefore if a shot should be placed just at the muzzle of the gun, the force of the impact of the gases against the rear end of the shot would be maximum, and the velocity communicated to the shot would be a minimum. 10. Q. And, therefore, the highest velocity is attained from a gun by having the shot down against the cartridge, is it ? A. When the charge is rammed or forced down against the powder cartridge in such a manner as to close up all the grains of powder into close contact with each other, and with the surface of the bore or chamber of the gun, the velocity of the projectile is greatest, and the strain upon the gun least possible from a like charge in a like gun. 11. Q. Did a gun ever burst from the premature bursting of a shell in the bore ? A. If a shell should be burst in the muzzle of a 15-inch gun containing a charge such as would nearly burst the gun in that part, but not quite, the force with which the fragments of the shell would be projected against the surface of the bore would cause numerous and deep indentations in the metal of the gun ; the cause of such indentations could not be easily misunderstood or overlooked, especially if we should be informed or believed a loaded shell lying in that part of the bore had been exploded while at rest. The part of the shell forming its largest diameter would be projected against the surface of the bore violently, and it would surely leave its mark if the force of the explosion reached nearly to the force necessary to rupture the gun. Yet I have examined 23 large guns which have burst at the muzzle : three of them were Dahlgren 11-inch guns ; one Dahlgren 8-inch gun ; two 10-inch; six 15-inch; two army 42 pound- ers, rifled ; one 32-pounder, rifled ; and eight large Parrott guns. I was informed, either by the persons who were present at the time of the accident, or by the ordnance department, that many of the accidents were attributed to the premature explosion of the shells in the bore; I therefore examined them carefully, and found not a single case exhibiting any enlargement of the bore whatever, and not the slightest indentation. It is quite impossible that so many cases of rupture could have occurred, or even that one could have happened from the premature discharge or explosion of the shells in the bore, without permanent enlargement of the bore or indentation, which would be apparent to the practiced eye even without the aid of instruments. 12. Q. If it is not the bursting of the shells in the bore, how do you account for the bursting of the guns at the muzzle I A. There is a correlation and conservation of heat and force. Heat and ability to perform work are exact equivalents. Force, while being resolved into motion, if restrained, is changed into heat ; if unrestrained, into work performed. So, if a man of the weight of 150 pounds climb a ladder to the interior of the dome of the Capitol, 100 feet high, his body becomes charged during his ascent with the ability to perform a definite amount of foot-pounds of work in descending again exactly 15,000. If he should grasp a rope which passed freely over a pulley and was fixed at its opposite end to a weight of 149 pounds down at the floor, by the descent of his body the weight might be raised to the same height from which he descended. To raise such a weight of 149 pounds to such a height 14,900 foot-pounds of work would be performed, 100 foot-pounds less than the descending weight would be capable of performing. The difference of 100 foot-pounds being expended in friction would be simultaneously resolved into heat. Suppose the rope were fixed so as not to flow over the pulley, but was grasped in the hands with such compara- tive tightness as to permit slipping slowly downwards ; so much heat EXPERIMENTS ON HEAVY ORDNANCE. 107 would be evolved by the friction as to burn the flesh off the bones of the hand. Thus, if the projectile is restrained in the gun by rubbing too tightly along the bore, the friction might create heat enough to weld the projectile to the gun. If one-half its projectile force should be restrained, one-half of its ability to perform work would be expended in heating the surface of the bore almost instantaneously ; this heat, of course, would be communicated to the interior in advance of heating the outside of the tube ; the force of the longitudinal and radial expansion would be sufficient to burst the gun. 13. Q. By the conservation of force cannot you account for the burst- ing of guns elsewhere than at the muzzle ! A. In a report made by Captain Thomas Edson on (the bursting of) the 13-inch Rodman gun at Fort Monroe arsenal during the firing from it, July 23 and 27, 1864, three rounds were fired on the 27th with 55 pounds of Dupont's ]STo. 5 powder and a solid shot of 283 pounds; the Eodman instrument gave a pressure for the three rounds of 152,000, 170,000, and 180,000 pounds, respectively: for the first two rounds 1,505 feet initial velocity; for the third round 1,800 feet. On the 23d two rounds were fired with the same kind of charge. At the first round the so-called pressure was 200,000 pounds to the square inch ; at the second round 160,000 pounds, and the initial velocity was only 1,188 feet per second. The rate of the velocity of these rounds, and the others, with the pressures shown, should have been 1,600 feet per second ; about one-fourth of the force of the charge was expended therefore in some other manner than in giving velocity to the shot. Let us suppose it to have been expended in friction along the bore ; resolve it into foot-pounds, according to this new light, " the conservation of force," and see what the result is in plain figures. The shot 13 inches in diameter has 132 square inches area, against which the expansive force of the powder acts in ejecting it from the gun. This area multiplied by the pressure in pounds to the square inch, 132x160,000 = 21,120,000 pounds of instant pressure against the shot. In order to simplify the calculation I will assume that this full pressure acts against the shot while it is moving along the bore, a distance of five feet. Then 21,120,000x5 = 105,600,000 foot-pounds. One quarter of these foot-pounds would be equal to raising 26,400,000 pounds one foot high, one pound 26,400,000 feet high, or 2,534,400,000 pounds one- eighth of a foot high; all these amounts of work being equivalents. All this intense force might be exerted in as practical a manner to burst a gun by unequal expansion, which would result from heating the surface of the bore in advance of heating the outside, as the same force could be directed by the best intelligence in any other manner; therefore it becomes necessary to devise guns and projectiles, if possible, which shall not in any contingency have any friction between the projectile and the surface of the bore. 14. Q. Is the pressure upon the square inch of surface for a small charge less upon the square inch of surface of the chamber than for a large charge"? A. There cannot be any materially greater force to act upon the chamber of a gun, resulting from a large charge of powder, than from a small one. A cubic inch of powder fired in a chamber which it fills will exert the same pressure upon the square inch of surface of the chamber as would be exerted upon a square inch of surface of a chamber with a cubic foot of capacity if also filled with powder. 15. Q. Has the friction of the gases or the grains of powder the effect to heat the interior of a gun! A. The friction of unburnt grains of powder sliding along the surface 108 EXPERIMENTS ON HEAVY ORDNANCE. of the bore would of course have a tendency to heat the interior of the gun more rapidly than the exterior ; but there is a greater force than this, which I discovered in the following manner also resulting from friction: In firing a 12-pounder rifled gun in 1861, I found that 1 pound of powder gave a higher velocity than any larger charge of pow- der. After proving the fact by firing the gun for range, a few shots were projected into a sand butt with three-pound charges, and upon recovering the projectile I found that part of the powder charge adhered to the rear of the shot, pressed into a cake, apparently as hard as soap- stone, which it resembled. Upon this I concluded that the loss of velocity was due to the fact that not more than one and a-half pounds of powder could be burned in a gun of that calibre, but did not notice at this time that the velocity was much less with three pounds than with a pound and a-half. At a later time I had occasion to fire a breech-loading gun of 12 pounds calibre, in which the chamber was larger than the bore, and having inserted the cartridge, accidentally, previous to the insertion of the projectile, I endeavored to force the cartridge through towards the muzzle, and finding it did not move easily, I applied increased force, using a block of wood with the blows of the sledge to drive it through, but in vain. I then endeavored to drive it back by the same means, but could not move it en masse either way. Upon digging out the pow- der with a pointed instrument of wood it was found in a hard cake resembling that which adhered to the shot in the previous experiment mentioned. From this I drew the conclusion that the retardation of the projectile resulted from excessive friction which attended the slip- ping of the unburned powder along the bore jammed behind the shot as it would be when the cartridge of an excessive charge was ignited at the rear end of the chamber. 16. Q. How can this be prevented ? A. When large charges are used it may be almost entirely prevented by igniting the cartridge at the front end ; so the projectile only will have to be moved along the bore while the unburnt powder is forced back- into the chamber. 17. Q. Do you know any other injurious forces which are exerted to burst guns which may be so controlled as not to have injurious effect ? A. I do. Guns are usually mounted so as to recoil backwards in a plane different from the plane of the bore when the gun is elevated. An improvement in the manner of mounting in this respect is needed: I exhibit on Plate XIV a plan which I have designed for this purpose. A gun should recoil backwards while the shot is being ejected exactly in the opposite direction to that in which the shot is moving; then there would be no greater pressure upon the bottom of the bore from the projectile than that due to the weight of the shot when at rest. The effect of the gun in recoiling in any other direction is to divert the shot from its aim, and results in greatly increased friction along the bottom of the bore detracting from the range of the projectile and exert- ing forces which have a tendency to break off the muzzle of the gun or burst it at the muzzle. When a gun is burst at the muzzle by any of these forces in combination or alone, no mark is left on the bore to indicate the cause of the accident, which is therefore, as I have saidbefore, erroneously attributed to the premature bursting of the shells in the bore. If it happen that the gun bursts when a solid shot is fired from it, or at a round when a shell is fired, which does not prematurely burst, the bursting is attributed all the same, and the premature bursting of some shell previously fired is referred to as the cause of the accident. Thus the whole subject is shrouded in impenetrable mystery and another a incongruous result" added to the already too long list. EXPERIMENTS ON HEAVY ORDNANCE. 109 18. Q. What is the cause of the enlargment of the bore of a gun at the seat of the shot so frequently referred to in the reports of the ord- nance department. A. When the pressure of the powder acts upon the rear of the pro- jectile in a gun, and before its front has motion imparted to it, the rear has moved forward; thus the axis which coincides with the longest axis of the bore of the gun is reduced in length and the diameter of the projectile is increased in all radial directions. While this occurs, the projectile being only in contact with the bottom of the bore, it must either penetrate the metal of the gun at the place of contact or the pro- jectile must be lifted up bodily. Usually the result is a little of both ; as the projectile receives its forward impetus along the bore, it therefore re- bounds; from its elasticity and the elasticity of the metal of the gun, it jumps upward and strikes the top of the bore a little forward of its first position ; glancing then downwards, it rebounds again from the bottom, and so goes on balloting from top to bottom until it escapes from the muzzle. This balloting has injurious effects upon the bore of the gun; it results in increased friction and consequently in increased temper- ature, which retards the velocity of the shot and destroys the paral- lelism of the bore and of the gun, inasmuch as it penetrates it or injures it irregularly ; of course guns are sometimes enlarged by the direct pres- sure of the powder arrested by tension. 19. Q. Cannot this be prevented? A. It can be when due to ballotting or upsetting of the projectile by supporting the projectile centrally in the gun with equidistant windage all around, previous to igniting the charge. 20. Q. Is there any direct communication of heat from the gases of the powder to the surface of the bore ? A. The heat of the gases of powder except by friction, or by the aid of currents, is communicated slightly or slowly. The heat of steam is communicated rapidly to any colder surface with which it is in contact ; because, as the heat is expended below 180, a vacuum, or partial vacuum, is formed. The current is thereby forced to flow with inconceivable rap- idity to the surface, receiving the heat, whereby the heat of the other steam, previously at a distance from the cooling surface, is communicated. In this steam is quite different from other gases containing heat, such as air, or the gases resulting from the combustion of the gunpowder, all of them being non-conductors, and all of them having an extremely low specific heat. Only the gas which is in contact with the surface of the bore of a gun imparts its temperature to it ; thus it is thereafter inter- posed as a non-conductor between the surface and the hotter gas at a distance ; which is thus prevented from giving its heat to the surface. With that part of the gas which is flowing through the vent or passing by the windage of the shot itself it is different. The large quantity pre- sented to the surface in quick succession in such a case communicates its heat, and immediately it passes away, giving place to other quantities. In this manner a larger proportion of heat is communicated to the vent than to another equal surface to which the gas is exposed in a gun : first, because the fire is lighted at the vent, and the hot gas flows longer over that part ; and second, because the vent passage is least liable to obstruc- tion. In the case of the rifle projectile the windage is usually entirely obstructed, and in smooth-bore guns unburnt powder grains, or the cart- ridge bag may be forced forward to stop the windage, and the passage of the heated gas past the shot. After the bore becomes worn at the seat of the shot, and the vent is injured, more heat is communicated than while the gun is new. More heat would always be communicated to the 110 EXPERIMENTS ON HEAVY ORDNANCE vent and the bore of the gun, by the passage of the hot gas, after they had become worn and rough from the slipping of the gases over the rough surface, causing increased friction and as a tendency to restrain the expansion of the gas in motion, as well as the motion of the projectile, causes force to be changed into heat, by friction which may act injuriously upon the gun, by unequally heating it and straining it through unequal expansion. 21. Q. Has no way been devised to prevent the heating of the gun metal about the vent ? A. A variety of the plans may be adopted to close the vent against the escape of the gas ; or the charge may be ignited without any vent, and thus a serious cause of injury to guns of large calibre may be obviated. 22. Q. Then is there any manner which may be adopted to prevent the communication of heat along the surface of the bore? A. The unequal expansion which results from the direct communication of the heat of the gases of powder, or the heat evolved from friction of the gas or of unburnt grains of powder, or powder jammed against the projectile, or rubbing or balloting of the projectile against the surface of the bore, is the principal cause of bursting of guns. The injurious effects may be prevented by making the gun elastic between the inner metal and the reinforce, according to a plan which I have devised, Plates XIII and XLV, and present herewith. 23. Q. What advantages does this gun possess over the Parrott gun of the same calibre, cast hollow, in your estimation ? A. It can be made to have a finer texture or molecular construction of the metal (see Plate VII) without injurious tensions, greatly increased strength to resist the forces acting upon it as a gun, from the increased rate of decarbonization admissible in its metal, which will increase its tenacity ; it will also increase the permanent elasticity of the metal, per 5e, and in addition to that, from its form or model it will have a wide range of elasticity to permit the radial and longitudinal expansion which results from heating the gun from the interior in any or all of the various ways I have alluded to. (See Plates XIII and XIV.) It can be made from the iron of old guns ; and it has been heretofore deemed impossible to re-cast the iron of old guns into new ones, as the strength and density are increased thereby, as can be learned by refer- ring to Rodman's book, (Appendix D,) which shows the strongest metal does not make the strongest gun, although the reason for that seeming paradox is not very plainly shown. It is undoubtedly because of the increased rate of decarbonization which results from remelting cast iron, keeping it longer in the melted state, or in fusion, giving greater tensile strength and the increased density which accompanies higher tensile strength, resulting from further decarbonization of cast iron. The higher the density, the greater the force with which the ex- pansion of the metal will be accompanied when heated ; and the greater the force of unequal expansion when unequally heated, as well as the greater tensions which will result from unequal cooling, is an effect of remelting or longer time in fusion. This gun (Plate XIV) can be made cheaper than the Parrott gun because no wrought iron is used in its con- struction, and no iron is wasted by turning off the gun along the chase; it will not be weakened or unequally heated by the waste of gas through the vent, because it has no vent, the charge being ignited at the front end of the cartridge by a revolving pin inserted through the cascable within a copper tube. Many of these details are not shown in the draw- ings. The friction of unburned or jammed powder along the bore is EXPERIMENTS ON HEAVY ORDNANCE. Ill also avoided by lighting the cartridge at the front end ; and the friction of the projectile against the surface of the bore is to be avoided by hav- ing no contact, except in the two rifled grooves, which are to be kept smooth and polished ; and the projectile is to be supported centrally in the gun, bearing only upon two gibs of brass, to slide in the grooves as freely as the cross head on a steam-engine piston-rod slides upon the guides, which will result favorably in giving increased velocity to the shot. The gun having but two grooves, (see details, Plate XIII,) neither of which cross the bottom or top of the bore, it remains essentially a smooth-bore gun for spherical projectiles, and is also available as a rifle. When spherical shot or shell are to be used the projectile is to be sup- ported centrally in the bore by three pins of brass projecting from its bottom, to rest on the bottom of the bore like the legs of a stool, thus preventing rubbing contact. 24. Q. Why could not the round projectile have the rifle motion im- parted to it ? A. It could. I forgot to mention that instead of the pins to support the projectile centrally in the bore it might be provided with the gibs to slide in the grooves. No more windage should then be given to the shot than experience taught would be equal to the radial enlargement under the pressure of the gases of powder ; improved accuracy and range would result. The rotary motion given to the round projectile would not render its ricochet uncertain 5 and the gibs might be so adjusted as to fly off after the projectile had left the gun. Sporting rifles are extensively used in the west with round bullets. 25. Q. Would not the unequal heating you have described, resulting from the friction or direct heat of the gas, affect the interior tube of this gun injuriously, or burs tit? A. Oh, no, sir ! because a tube having no more than four inches of thickness may be melted by heat communicated entirely to the interior surface without bursting it. Field and siege guns do not burst, however rapidly they are fired, if the wall of metal surrounding the bore is no more than four inches thick ; it is only the metal of the reinforce, which surrounds that thickness in larger guns, which is ruptured by unequal expansion. 26. Q. Then why make any gun of greater thickness? A. Simply because if the calibre is large it requires the strength of a thicker Avail to resist the direct pressure of the powder. There is no trouble attends making small guns ; and it is to be noticed that all gun- makers have achieved their reputation on small guns. Sir William. Armstrong made a small gun first, and it exhibited remarkable qualities of accuracy and range. His field guns afterwards were highly approved. He only met serious difficulties when large calibres, involving more than four inches thickness of wall, were attempted. So also with the guns produced by Mr. Parrott ; first 10-pounders, then 20-pounders, and 30- pounders, all of which were successful guns. One of the 30-pounders endured 4,600 rounds, on Morris island ; and although the 100-pounder endured the proof of slow firing, at the foundry, showing that the strength was sufficient to withstand the pressure of the powder, the first one fired rapidly, in service, viz., the one on the steamer Naugatuck, in the attack on Fort Darling, was burst ; and afterwards all of that class of guns of large calibre, and the necessary thick walls, whenever sub- jected to conditions which heated them unequally, burst likewise. 27. Q. Then why will not the direct pressure of the powder burst the gun you propose, which has a thin tube of iron about the bore ? A. Because a pressure nearly equal to the strength of the reinforce 112 EXPERIMENTS ON HEAVY ORDNANCE. is exerted on the outside of the tube, by contracting the band upon the edge of the webs which surrounds the tube; each web being a beam to support the tube forward and behind the band, and if this pressure exerted by the band equals the pressure the powder would exert from the inside of the tube, there is no tendency to break it or enlarge it. The pressure of the reinforce is exerted upon this thin tube as if springs were inter- posed between it and the band. (See cross- section, Plate XIV.) The pressure of the powder is not sufficient to bend the springs further, although the greater force, resulting from heating the interior to expand the tube, may be sufficient to bend them to a slightly greater extent than they would be bent by the tension of the reinforce. There is such a wide difference or margin between the " instant pressure 77 of the force which results from the pressure of the powder, and that of the force which results from expansion of the metal by heat, that it is quite prac- ticable to interpose these springs between the interior and exterior of the gun, and thereby restrain the pressure of the powder, and permit the expansion by heat, which cannot be restrained. (See cross-section of details, Plate XIII. ^ 27. Q. But the tube will expand lengthwise, also ; how can you pro- vide for that? A. By the peculiar form of the springs, or webs ; they are made to have elasticity for the lengthwise as well as the radial expansion. (See ele- vation, 200-pounder rifle, Plates XIII and XIV.) 28. Q. Could this gun be made of wrought iron? A. It could very well ; but the ductility of wrought iron is a very objectionable quality for guns. Wrought iron will stretch permanently under a force which, if exerted upon equal ultimate strength of cast iron, would only enlarge it within its permanent elasticity, and it would recover after the force was removed, and wrought iron would not. Wrought iron is also softer, and would be more easily abraded and scratched in the bore ; it is more rapidly wasted by rusting and more subject to the action of acids of powder than cast iron or steel ; the carbon protects the latter from the rapid action of oxygen or acids ; carbon having a stronger affinity for oxygen than iron has, the oxygen unites with the carbon first. We owe it to this fact that we can make wrought iron from cast iron, to do which only requires the extraction of the carbon from the cast iron or steel. Wrought iron has the other objectionable quality as a material for guns, viz: that it cannot be made homogeneous. It is not practicable to melt and flow it in the liquid state into the required form of uniform structure as we can with cast iron ; it must be welded, and the welds are places of weakness. The cost of a wrought-iron gun is about four times as great as the cost of a cast-iron gun. 29. Q. I see in Holley's book (Fig. 160) an account of fissures which occurred in a large mass of wrought iron, which were attributed to some other cause than bad welding. Is it common to find defects in that kind of iron? A. Fissures of that kind (Plate X) only happen when the mass is large, and are caused by " the contraction from the centre towards the circum- ference as the mass cools." They are, in fact, an effect of unequal con- traction resulting from unequal cooling, and resemble the cavities found in the centre of large masses of cast iron half-way between the cooling surfaces, if exposed to an equal rate of cooling from all the surfaces. I have here a piece of iron, broken from the centre of a large mass, which you will notice is of a very coarse structure, (Fig. 4, Plate VII;) the faces of the crystals are one-fourth of an inch across; and another piece cast EXPERIMENTS ON HEAVY ORDNANCE. 113 at the same time from the same lot of melted iron of a smaller diam- eter. The molecular structure of the iron of the thin part (Fig. 1, Plate VII) is entirely different 5 it is as fine grained as cast steel. These peculiarities of structure pf iron, (Plate VII,) due, it is supposed, entirely to the different rate of cooling or freezing from the liquid to the solid state, are not sufficiently attended to by metal workers. The finer the molecular structure, the stronger and better the fabrication made from the iron. In wrought iron the same differences of size of grain can be seen. With this knowledge I designed the guns shown on Plates XIII and XIV. 30. Q. It has been represented to us that fibrous wrought iron is much stronger than crystallized iron ; is that so f A. Undoubtedly j even to a greater degree than the fine-grained cast iron excels in tenacity, elasticity, and density the coarse-grained iron. The difference of structure is shown in Figs. 5 and 6, Plate XI. In a mass as large as is required for a gun there is no such thing as fibre ; the structure is entirely changed by cooling from or heating to the weld- ing temperature, as slowly as a large mass must be heated or cooled ; the molecular structure is entirely changed by once heating to the weld- ing temperature, if the mass is large. 31. Q. Among the forces which you have mentioned as resulting from the combustion of gunpowder, you have referred to the expansive force ; is not that a principal force to be restrained, and can it be restrained ? A. It can ; the whole of the expansive force of gunpowder under com- bustion has been frequently restrained when fired in a chamber which it filled. I have conducted such experiments myself, and have heard of the experiments of others, in which the force was restrained completely. However, if I were about to design or make a gun of any calibre which had been made previously by any other person of the same material and which had endured one or two heavy charges equal in weight of and rapidity of combustion of the charge I wished to use, I would depend upon the data relating to strength by thickness of wall in that gun, and adopt equal or greater area of cross and longitudinal sections ; then, by increased tenacity, density, and elasticity in the metal used, get a margin of strength to restrain the direct pressure. I would then take care to have 110 injurious tensions from the rate of cooling, and with the elasticity which my improved model would give to provide for the une- qual expansion, I would expect to get a gun which would absolutely restrain the direct pressure, and permit the unequal expansion resulting from firing, which need not be restrained. 32. Q. What is initial tension, so frequently referred to, and how does it affect the endurance of guns I A. Initial tension is an inert force or strain, inaugurated in a gun or any other piece of metal, induced usually by unequal cooling, causing one part of the mass to endeavor to pull away from or towards another part, or both. The part which cools first in any mass is subjected to a strain of compression, and the part which cools last to a strain of exten- sion. The castings, Plate XV, which I have prepared and exhibited to the committee, lately placed in the hall of the old House of Bepresentatives, were intended to represent the excess of this tension from unequal cool- ing. These castings were referred to in a late report of the Chief of Ordnance, General Dyer, as having been prepared by u ignorant or designing persons," and the maker was credited with having hindered the furnishing by the department of 1,915 large guns. I hope you will credit me with having prevented the perpetration of a gigantic swindle upon the treasury thereby. Eep. No. 266 8 114 EXPERIMENTS ON HEAVY ORDNANCE. Metals expand while being heated with a force which exactly equals the measure of their ability to resist compression at each different tem- perature if their expansion be resisted sufficiently, and contract in cool- ing with a force which equals the resistance to extension of the same metal. These experimental castings, it may be seen, have broken in their strongest part, where the area of cross-section ruptured is twelve square inches. If we assume the tensile strength of the iron to be only 20,000 pounds to the inch, the tension necessary to break it amounted to 240,000 pounds, the outside bars having a larger amount of cooling surface, while the quantity of metal to be cooled is less, became frozen while the iron of the middle bar was in the liquid state. The later con- traction of the part cooled last (the contraction being restrained by the rigidity of the part cooled first) was the cause of the rupture. If the length of the casting had been less it might have happened that the extent of the contraction of the middle bar would have been within the " permanent elasticity," and the measure of ductility of the iron ; it would not in that case have been broken, although the tension might have been nearly great enough to break it ; it would then be in the state of initial tension. It can be seen that a casting might be made and strained so nearly to the point of rupture, that the heat of the hand, (if warmer than the iron,) laid upon the compressed part, would be suf- ficient to complete the rupture or burst it. Those Rodman guns which have burst in the foundry previous to hav- ing been subjected to the powder proof, were burst by the excess of the initial tension, caused by cooling the gun, or the cast block from which the gun was to be made, from the interior"? 33. Q. Are the views contained in your evidence in relation to metals, force of powder, and endurance of guns, confirmed by the opinions of experts, by the reports, and by recorded authorities? A. They are my conclusions, based upon a careful reading of reports and authorities, upon my own practical experience as a metal worker, my own experiments and observations as a gun maker, and a long and earnest study of the natural philosophy involved in the subject. If you will permit me, I will revise my evidence and interpolate references to the reports, authorities, and experiments' upon which my statements are founded. 34. Q. You can do so. How will the cost of testing guns upon the plan you have proposed compare with the system now practiced by the army and navy ordnance departments ? A. The cost would be immeasurably less, as the extreme proof would determine at once the quality of the gun and of all other guns made of the same calibre, form, or model, material, and manipulation of material ; while it can be seen that the old extreme proof determined nothing except that the particular gun tried either burst or did not burst, enlarged or did not enlarge; that the vent either did or did not wear, and that the interior either cracked or did not crack. The uncertainties attending the proof of guns are referred to frequently in the reports a's u incon- gruous results, 77 while the question relating to the endurance of guns remains involved in mystery. General Dyer, in his last report, dated October 19, 1868, says: In the last annual report from this office the unanimous opinion of the board on the aruia^ ment of the fortifications ****** was quoted, showing the necessity of a large number of smooth-bore and rifle cannon for such armament. In pursuance of this opinion, approved by the War Department, and at the request of the Chief of Engineers, a few of these cannon have been ordered, and are now nearly finished and ready for trials to test their power and endurance. In the report of the same officer for the preceding year, the endurance EXPERIMENTS ON HEAVY ORDNANCE. 115 of a 12-inch Eodraan rifle gun was referred to as establishing that guns of that class exhibited endurance superior to any gun of the calibre in the world, without referring to the important fact that four only of that kind of gun had ever been made, and that three of them had burst pre- viously to the date of that report. Since that time the fourth one has burst, and it is now rumored that two or three others referred to in the report of October 19, 1868, as of the few which have been ordered, have been disabled during the experiments on iron defences by the engineers. The extraordinary part of this business is that while the ordnance depart- ment of the army is engaged apparently in efforts to bolster up the character of guns which fail so suddenly that it is difficult to make the report and print it before the guns are disabled, the Chief of Ordnance of the navy says, in his corresponding annual report: Opinions differ quite as widely (referring apparently to almost every question involved in designing, constructing, mounting, and using ordnance) in regard to the preferable mode of developing ordnance power ; whether it shall be by smooth or rifle bores ; by loading at breech or muzzle ; made of iron, cast or wrought, or from steel; solid, or in connected parts. The relation of mass to velocity is also unsettled. It seems to me that it is plainly the duty of Admiral Dahlgren to report his own conclusions in relation to these important points, while it seems also quite as plain that he prefers to continue expending public money in repeating old worn-out kinds of experiments, and recording the most minute and inconsequential facts in relation to such experi- 'ments, instead of wrenching himself in the public service, to the extent he would if he should advance an original idea*>r give an opinion with a reason. Who is there so ignorant about ordnance in these days as not to know, for instance, whether it is practicable or better to load guns of the larger calibres at the breech, after the exhaustive experiments con- ducted in England with the Whitworth and Armstrong guns, if the guns did not fail ; and that the return to muzzle-loaders in that country for large calibres was on account of the failure of the guns, and not other- wise ! Who does not know the relation of mass to velocity ? Mass or weight is one element of ability in a projectile to perform work, and velo- city the other. Could not all the experience of Admiral Dahlgren enable him to state as a fact, that a projectile, however heavy or large it might be, could not penetrate air, water, wood, earth, stone, or iron, if it had no motion or velocity, and that it could not do so either, even with velocity or motion, if it had no mass or weight? Has Admiral Dahlgren never seen the calculations of Captain Noble, of the royal artillery of England, of the foot tons of work per inch of circumference, stored up in projectiles having different weights and velocities, or the simple rule upon which the calculation is made? If he has not, what is the use of continuing expenditures of public money for experiments under such obtuse direction ? No valuable conclusion can ever be arrived at in so indirect a manner. On the 22d of November, 1862, this same officer, in his report as Chief of Ordnance, referring to " the construction and armament of our ships of war," said: "And yet no definite conclusion has been reached in regard to either of these important problems;" and, although a war was then raging, referred on the same page to the part of the question relating to the guns, with the refreshing complacency exhibited in the following quotation: "so that we have the leisure to consider and devise any other species of ordnance that may be better adapted to the purpose, and are not precipitated inlo hasty or questionable measures." Obtuseness and complacency of the navy ordnance bureau is, however, no more effectually opposed to progress in the art of pro- ducing guns, than the politic shrewdness or smartness of the army 116 EXPERIMENTS ON HEAVY ORDNANCE. ordnance corps, and their selfishness in precluding from the sacred precincts of the inner sanctuary of the department all inventors of guns. 35. Q. After a gun has burst could you determine whether it was pressure of the powder, toa great tension, or too little, or the unequal heating from the interior which was the principal cause of the rupture from the nature of or direction of the fracture ? A. I think we can determine that almost with certainty. It is to be noticed that all unbanded guns burst with such uniform direction of fracture as to lead to the conclusion that the bursting is according to law ; at the same time this direction is not that one which could possibly result from pressure of the powder alone. About twenty years since Gen- eral Rodman proceeded to consider the forces acting to burst a gun, and assumed the gun to be made up of staves shown by diagrams in his re- ports, (see Plate Y, Fig. 1 and Fig. 3,) and assumed correctly enough that the effect of this pressure would be to bend these imaginary staves out- ward, as shown in Fig. 1, Plate Y. He then erected a diagram to show the kind of fracture which would result from pressure; in this he was also singularly correct. This kind of fracture is shown by Fig. 1, Plate Y. Its correctness is shown by the fracture of a cylinder actually burst by water pressure during one of his experiments, (see Fig. 7, Plate Y.) Now I believe myself to be the only person who ever asked attention to the fact that this kind of fracture is a kind that never occurred to a gun burst by firing. I was surprised to find that General Rodman, however, had not yet seen the point which I have urged in this connection for the past six years, for in giving his testimony before this committee a few days since, he referred to the staves and the strength of the breech as If no other force but the pressure of the gas measured by his instrument had anything to do with the bursting of guns behind the bottom of the bore, where the pressure don't act at all. and expressed the opinion that the gun shown in Fig. 2, Plate II, began to rupture at the breech and split forward, and he treated the subject very tenderly when describing the bursting of guns on improved models, Plates II and III, which broke through the breech in the same manner, although they have a greater thickness at that part. Plates II and III exhibit the general direction of fracture in all unbanded guns; and Fig. 4, Fig. 5, and Fig. 6, Plate Y, are intended to show why guns burst through the breech and refuse to follow the direction of fracture due to pressure alone, according to the diagram, Fig. 2, Plate Y, Fig. 4, same plate, shows the curved form which the two outside plates of three iron ones would assume if heat should be communicated to their inside surfaces only by heating the middle plate red hot and adjusting it between the other two, when cold and straight. By imagining three such plates placed upon the diagram of a burst gun, as in Fig. 6, Plate Y, the cause of the invariable bursting through the breech in guns of this kind can be understood. The heat added to the interior of the gun causes the extension lengthwise of the interior iron, and forces the reinforce into the curved form shown in Fig. 4, Plate IY. This is also illustrated in Fig. 1, Plate Y. The reinforce extended by the expansion of the interior and the refusal of the exterior to extend with it is the principal cause of the rupture undoubtedly. The Parrott banded gun, Fig. 1, Plate I, has the same character of fracture from the same cause. If a narrow band had been placed on the columbiad, Fig. 1, Plate YI, just over the seat of the shot, although it might have prevented the rupture under the band, it would have had no tendency to have prevented that part of the rupture reaching from forward of the trunnions back to the band; and this explains that kind of rupture shown in the Parrott gun, Fig. 4, Plate I, Fig 5, Plate I, EXPERIMENTS ON HEAVY ORDNANCE. 117 which, however, only cracked on the outside. Ruptures along the chase and at the muzzle have been sufficiently explained in answer to previous questions. It is important to consider the cause of the blowing out of the breech. Plate X, Fig. 1, shows a Whitworth gun, which was one of two disabled in the naval battery on Morris island; the inner tube extended and protruded one inch, as shown. This inner tube would not have extended so far out at the breech if it had been allowed to ex- pand when heated by firing in all other directions. The bands prevented it from expanding radially. If the band had been shrunk on with screw threads fitting upon the inner tube so as to prevent extension lengthwise as well as radially, the gun would have burst with the same direction of fracture as is shown in columbiad, Fig. 2, Plate V, or else it would have broken transversley in the same manner the 300-pounder Armstrong, Figs. 3 and 4, Plate X, broke, i. e. s transversely; so also the heating the Parrott, Fig. 2, Plate X, only half way through the wall of cast iron under the band had the tendency to expand the interior radially and longitudinally, but its expansion (rememember only heated half the thickness of the cast iron from the inside) was restrained radially by the band. The result was, the breech was pushed out just the same as the 300-pounder Armstrong, Fig. 4, Plate X. Thus it can be seen that unequal expansion of the metal of the gun from the interior, resulting from the direct heat of the gas of the powder undergoing combustion, or the heat coming from friction, is the principal cause of all the different kinds of ruptures of guns. APPENDIX B. Correspondence. WASHINGTON, D. 0., December 24, 1868. SIB : I have the honor to request that you will furnish as soon as prac- ticable answers to the following questions, for the information of the Joint Select Committee on Ordnance: 1. What different calibres and kinds of guns larger than 32-pounder smooth-bores and 30-pounder rifles are now mounted on or prepared for the fortifications? 2. What is the nature of the proof or experiments to which the different kinds and calibres before mentioned have been subjected to respectively to enable the department to determine upon the propriety of accepting the guns for service? 3. How many rifled guns of 8-inch calibre or larger, cast hollow, have been made either for the army or the navy, and subjected to proof or ex- periment! What has been the endurance of each of the guns? What is the present state of each, and what was the nature or extent of the proof on experiments in each case I 4. What guns cast hollow for the army have exhibited cracks or rup- tures on the outside previous to being subjected to the powder proof, together with the nature and extent of the rupture? Very respectfully, your obedient servant, J. M. HOWARD, Chairman Joint Select Committee on Ordnance. Lieutenant Colonel T. J. TREADWELL, Acting Chief of Ordnance, Washington, D. C. 118 EXPERIMENTS ON HEAVY ORDNANCE. ORDNANCE OFFICE, WAR DEPARTMENT, Washington, January 23, 1869. SIR: I have the honor to report as follows in reply to your communi- cation of the 24th ultimo : Question 1. What different calibres and kinds of guns, larger than 32-pounder smooth-bores and 30-pounder rifles are now mounted on or prepared for the fortifications ? There are mounted or ready to be mounted at the forts as follows: SMOOTH-BORES. 1 20-inch Eodman gun. 294 15-inch Eodman guns. 1 13-inch Eodman gun. 1, 233 10-inch Eodman guns. 147 10-inch columbiads. 155 8-inch Eodman guns. 339 8-inch columbiads. 30 8-inch sea-coast howitzers. 33 8-inch siege howitzers. 143 42-pounder guns. 2 16-inch mortars. 17 13-inch mortars, sea-coast. 2 12-inch mortars, sea-coast. 34 10-inch mortars, sea-coast. 59 10-inch mortars, siege. 26 8-inch mortars, siege. 2, 516 total smooth-bores. RIFLED GUNS. 2 12-inch Eodman guns. 28 300-pounder Parrott guns. 48 200-pounder Parrott guns. 133 100-pounder Parrott guns. 34 4J-inch siege guns. 245 total rifled guns. Besides the foregoing there are at the arsenals, available for mounting SMOOTH-BORES. 2 15-inch Eodman guns. 24 10-inch Eodman guns. 8 10-inch columbiads. 46 8-inch Eodman guns. 63 8-inch columbiads. 15 9-inch Dahlgren guns. 2 10-inch sea-coast howitzers. 6 8-inch navy guns. 58 8-inch sea-coast howitzers. 184 8-inch siege howitzers. EXPERIMENTS ON HEAVY ORDNANCE. 119 31 42-pounder guns. 1 16-inch mortar. 41 13-inch mortars, sea-coast. 70 10-inch mortars, sea-coast. 30 8-inch mortars, sea-coast. 124 10-inch mortars, siege. 154 8-inch mortars, siege. 859 total smooth-bores. RIFLED GUNS. 1 8-inch Eodman gun. 11 300-pounder Parrott guns. 33 200-pounder Parrott guns. 55 100-pounder Parrott guns. 12 7-inch wrought-iron guns. 73 42-pounders, banded. 75 4J-inch guns. 107 32-pounders, banded. 367 total rifled guns. RECAPITULATION. Smooth-bores. Rifled. At forts 2, 516 245 At arsenals 859 367 Total 3, 375 612 Question 2. What is the nature of the proof or experiments to which the different kinds and calibres before mentioned have been subjected respectively to enable the department to determine upon the propriety of accepting the guns for service f Prior to 1861 the proof of iron guns was three rounds two with a charge of powder equal to one-half of the weight of the shot, two shot and one wad ; the third a charge of powder one-third the weight of the shot, one shot and one wad. For columbiads the proof was two rounds 10-inch, first round, 20 pounds of powder, one shot, and one wad; second round, 24 pounds of powder, one shot, and one wad. For the 8-inch first round, 12 pounds of powder, one shot, and one wad ; and for the second round, 15 pounds of poAvder and one shell. The proof of howitzers and mortars was a corresponding scale. In 1861 the proof for all guns was fixed as follows : (Ordnance Manual, 1861, page 30:) 15-inch columbiad, 3 rounds, 50 pounds powder, and 1 shell. 10-inch columbiad, 3 rounds, 18 pounds powder, and 1 shot. 8-inch columbiad, 3 rounds, 12 pounds powder, and 1 shot. 32-pounder gun, 3 rounds, 9 pounds powder, and 1 shot. 24-poundor gun, 3 rounds, 8 pounds powder, and 1 shot. 18-pounder gun, 3 rounds, 6 pounds powder, and 1 shot. 12-pounder gun, 3 rounds, 4 pounds powder, and 1 shot. 120 EXPEKIMENTS ON HEAVY OKDNANCE. 8-inch siege howitzer, 3 rounds, 4 pounds powder, and 1 shot. 24-pounder howitzer, iron, 3 rounds, 3 pounds powder, and 1 shot, strapped. Field guns, bronze, 3 rounds, $ weight of shot, and 1 shot, strapped. 32-pounder howitzer, bronze, 3 rounds, 3 pounds powder, and 1 shot, strapped. 24-pounder howitzer, bronze, 3 rounds, 2- pounds powder, and 1 shot, strapped. 12-pounder howitzer, bronze, 3 rounds, 1 pounds powder, and 1 shot, strapped. 12-pounder mountain howitzer, bronze, 3 rounds, pound powder, and 1 shot, strapped. Coehorn mortar, 3 rounds, pound powder, and 1 shell. 13-inch sea-coast mortar, 3 rounds, 20 pounds powder, and 1 shell. 10-inch sea-coast mortar, 3 rounds, 10 pounds powder, and 1 shell. 10-inch light mortar, 3 rounds, 5 pounds powder, and 1 shell. 8-inch light mortar, 3 rounds, 2 pounds powder, and 1 shell. 4^-inch rifled siege guns, 3 rounds, 4 pounds powder, and 1 shot. 3-inch rifled siege guns, 3 rounds, 1^ pounds powder, and 1 shot. In January, 1862, when it was determined that guns should be cast hollow and cooled from the interior, the following requirements were prescribed : That one trial gun should be made by each founder receiv- ing orders ~or accepting a contract; the gun should be made of warm or cold blast charcoal iron, to have a tenacity of not less than 30,000 pounds per square inch, to be determined by specimens taken from the sinking head of the gun and from a cylinder cast from the same heat and from the same metal ; the trial guns to be fired 1,000 rounds with service charges of powder, 200 with solid shot and 800 with shells, and if the gun stood the test the order to be filled with guns made of the same metal treated in the same manner, and to be received upon endur- ing the proof established in 1861. The 7-inch wrought-iron rifles were proved by firing 10 rounds with 20 pounds of powder and one shot weighing 125 pounds. The rifled guns heretofore procured having been considered entirely as experimental, a provisional proof was fixed for such guns. The Parrott rifle guns were procured as a necessity during the war, but before putting them in service one 100-pounder was subjected to a test of 1,000 rounds with charges of 10 pounds of powder and one shell, which it endured ; subsequently the 200-pounders and 300-pounders were subjected, one of each to a test of 100 rounds the 200-pounder with charges of powder of 15 and 16 pounds, and one shell of 150 pounds, and the 300-pounder with charges of 25 pounds of powder and one shell weighing 252 pounds, which test they endured. All guns of these three calibres subsequently procured were proved with 10 rounds of similar charges. In the fall of 1864 the department appointed an officer to superintend the construction of cannon, with authority to dictate to founders the kinds of metal they shall use, the manner in which it shall be treated, and the properties it shall possess after being cast into guns, such as tenacity, specific gravity, initial strain, and texture of fracture. These being satis- factory, the responsibility of the powder-proof was assumed by the depart- ment. All guns cast hollow and cooled from the interior, since that period, have been received on these conditions, but are, nevertheless, subjected to proof according to the regulations of 1861. The ordnance board, at its meeting of January, 1868, fixed the proof of 15 and 13-inch guns at two rounds of 100 pounds of powder and one solid shot for the former, and the same number of rounds of 80 pounds of powder and one solid shot for the latter, and further recommended that all 15-inch guns heretofore procured, whether proved or not, should be proved with this charge of 100 pounds of powder and one shot. This will be done as fast as the guns are mounted, or other suitable facilities afforded for the purpose. Question 3. How many rifled guns of 8-inch calibre, or larger, cast EXPERIMEMTS ON HEAVY ORDNANCE. 121 hollow, have been made either for the army or the navy and subjected to proof or experiment I What has been the endurance of each of the guns ? What is the present state of each, and what was the nature or extent of the proof or experiments in each case ? The number of rifled cannon of 8-inch calibre and larger, cast hollow, which have been procured by this department, is as follows : Three 12-inch Eodman guns; three 8-inch Rodman guns; forty-one 200-pounder Parrott guns ; forty 300-pounder Parrott guns. The first 8-inch rifle, which was made at Fort Pitt foundry, was sub- mitted to a test of 1,047 rounds with charges ranging from 9 to 16 pounds of powder and one projectile, and burst at the last round. Two 8-inch rifles were subsequently made at the South Boston foundry, and were tested, one with flanged and the other with expanding projec- tiles, and with charges of powder ranging from 14 to 16 pounds. The one fired with flanged projectiles burst at the 80th round ; the one fired with expanding projectiles has endured 808 rounds and is still ser- viceable. The first 12-inch Eodman rifle was fired 472 times, with charges ranging from 35 to 70 pounds of powder, principally 50 pounds, and one projectile, and burst at the last round. A 12-inch gun, cast hollow and rifled on the Atwater principle, was turned over to the ordnance department by the navy, and was tested at Fort Monroe. The history of this gun, prior to its transfer, is not known. It was fired at Fort Monroe, 30 rounds with from 50 to 55 pounds of powder and one expanding shot or shell, and burst at the last round. Two 12-inch Eodman rifles were recently procured and have been fired, one at Fort Monroe and the other at Fort Delaware. Detailed reports of the firing made with rifled guns have heretofore been furnished to the committee, except the firing of 8-inch South Boston rifle, No. 2, subsequent to the 771st fire, the 12-inch No. 1 from the 428th to the 472d fire, and the firing with the last two 12-inch rifles ; and copies of these reports are appended hereto. Copies of the preliminary experiments made with the Parrott 200- pounders and 300-pounders have also been heretofore furnished to the committee, and are respectfully referred to. Two of these 300-pounders and eleven 200-pounders have failed in service; but it cannot be stated what portions of these were cast hollow or solid. Question 4. What guns cast hollow for the army have exhibited cracks or ruptures on the outside previous to being subjected to the powder proof, together with, the nature and extent of the rupture I No gun cast hollow for the army which exhibited cracks or ruptures on the outside previous to being subjected to powder proof has been offered by the founder, or received by the United States. Several such guns, to the number of 98, exhibiting defects, were made for the army, but were either withdrawn by the founders or rejected by the inspectors. The nature and extent of the defects, as described in the manufac- turers' reports, are as follows : 15-inch guns 6 10-inch guns 82 8-inch guns 1 300-pounder Parrott 1 8-inch siege mortars 8 Of the first, two were for dra wholes, one for being too large in bore, one for too low tenacity, one cracked in lathe, and one condemned in pit. Of the second, sixteen were for drawholes, twelve for holes in bore, 122 EXPERIMENTS ON HEAVY ORDNANCE. thirty-one for low tenacity, one for high density, one for metal too soft, seven failed in casting, and nine failed in mechanical tests, one for too much initial strain, one condemned in mill, two cracked, and one burst in lathe. The 300-pounder condemned in mill. The 8-inch gun for holes in muzzle, and the 8-inch siege mortars con- demned by the founder. Very respectfully, your obedient servant, T. J. TBEADWELL, Bvt. Lieut. Col. and Major of Ordnance, in charge. Hon. J. M. HOWARD, Chairman Joint Select Committee on Ordnance, U. S. Senate. WASHINGTON, D. 0., December 24, 1868. SIR : I have the honor to request that you will furnish, for the infor- mation of the Joint Select Committee on Ordnance, answers to the following questions: 1. What is the total number, kinds, calibres, and weights, respectively, of guns now or at any time mounted on iron-clad ships of the United States, from the time of the arming of the first monitor to the present time? 2. How many trial guns were originally or at any time procured or fired to extreme proof as the basis of the acceptance of the different kinds and calibres of guns mounted on such iron-clad ships ? 3. What was the character of the extreme proof, ^ordinary proof, and experiments, to which each system, kind, and calibre, was severally sub- jected'? 4. How far has the navy Ordnance Bureau accepted the tests, proofs, and experiments made by the army ordnance department towards enabling the bureau to determine what kind of guns should be adopted for service, and how far, within the knowledge of the bureau, has the army ordnance department accepted the tests, proofs, and experiments of the navy as conclusive towards enabling it to determine the proper system to be adopted in arming the fortifications with heavy guns? 5. What fissures, cracks, and ruptures, (together with the locality and extent of the same,) have at any time been noticed or reported to the bureau as having occurred on the outside of guns larger than 32-pounders, previous to the guns having been subjected to the powder proof; also, what cracks, fissures, and ruptures have been noticed or reported on the inside of guns previous to firing; together with the kind of gun, and whether the notice or report was official or otherwise? 6. What fissures or cracks have been reported to the bureau as having occurred upon the outside or inside of guns larger than 32 pounders, during proof or experiments with powder, together with the nature or extent of the accident, where the gun was not completely burst? 7. What was the nature of the extreme proof and the ordinary proof prescribed for guns of large calibre by the bureau in the years 1850, 1855, 1860, and 1865, and also at the present time; also, so far as is known to the bureau, what was the extreme proof and ordinary proof for like guns prescribed by the army ordnance department at the same dates? 8. On what occasion was the 15-inch gun subjected by the navy to the most rapid firing for as many as fifteen consecutive rounds, with shot or shell, and with nearly uniform intervals of time between the shots ; EXPERIMENTS ON HEAVY ORDNANCE. 123 what interval of time elapsed between the respective rounds, and fur- ther, whether the gun was fired in service or during experiments ; also, what official knowledge, if any, is possessed by the bureau of 15-inch guns having been fired by the army in a similar manner in service or during experiments ? 9. Give like information with regard to the 8 and 10-inch Parrott rifles. 10. What has been the most rapid firing for any number of consecu- tive rounds with the 15-inch gun, the larger Parrott rifles, or the hollow cast rifles, with nearly uniform intervals between the shots? 11. What 15-inch guns or rifles of large calibre were injured, disabled, or burst while in service during the late war, or while undergoing proof or experiment, together with the nature of the gun and the character of the injury? 12. What system of rifled guns of 150 pounds calibre or larger have been subjected to proof or experiment by the navy? What guns of that calibre, or larger, have been adopted or accepted for experiment by the navy? 13. To what proof on experiments has each system and calibre which has-been accepted been subjected? Which system exhibited the greatest endurance? Which the least? What has been the average endurance of each system and calibre for all the guns made, tested and experimented with ? What system of rifled guns of large calibre is now approved by the Ordnance Bureau of the navy ? The committee respectfully request that answers to these questions be given as early as practicable. Very respectfully, your obedient servant, J. M. HOWAED, Chairman Joint Select Committee on Ordnance. Bear- Admiral JOHN A. DAHLGREN, Chief of Ordnance, Navy Department, Washington, J). C. BUREAU OF ORDNANCE, NAVY DEPARTMENT, Washington City, February 11, 1869. SIR : I have the honor to transmit herewith replies to the questions of your honorable committee, which, I regret to say, are more or less incom- plete. I have done, however, as much as the time has permitted since receiv- ing the wishes of the committee on the 25th of December last. I am, sir, with great respect, your obedient servant, J. A. DAHLGEE^, Rear-Admiral and Chief of Bureau. Hon. JAMES M. HOWARD, Chairman Joint Select Committee on Ordnance, U. S. Senate. Reply to query 1. There have been three calibres of cannon mounted on sea-going iron- clads of the navy, viz : Pounds. 11-inch, of my design, smooth bore 16,000 Short 15-inch, of my design, smooth bore 42,000 Long 15-inch, not of my design 42,800 Eifled 8-inch (150-pouuder) Parrott 16,500 124 EXPERIMENTS ON HEAVY ORDNANCE. The first monitor carried two 15-inch guns. The vessels of the class next built were larger, and most of them carried in the turret one 15-inch (short) gun and one 11-inch, such as the Passaic, Moiitauk, Katskill, Weehawken, Nantucket, Nahant, and Sangamon. Two of them carried a 15-inch (short gun) and a Parrott 8-inch rifle, viz : Patapsco and Lehigh. The Mont-auk's short 15-inch was replaced by a long 15-inch, and that subsequently by another long 15-inch. The next class of monitors carried in the turrets two short 15-inch guns, viz: Tecuinseh, Manhattan, Canonicus, Saugus, Camanche. Some had two long 15-inch, such as the Maiiayuiik, Tippecanoe, Catawba, and Oneota, which were built in the western inland waters, but were capable of ocean service. The double- turret monitors had four 15-inch, viz : the Monadnock, Miantonoinah, Tonawanda, Agaruenticus. The large ocean monitor Dictator carried two 15-inch in the turret. The Roanoke, with three turrets, had a 15-inch and an 11-inch in one turret, a 15-inch and 150-pouuder in the second turret, and an 11-inch and 150-pounder in the third turret. The river monitors of one and two turrets had only 11-inch in each turret, viz: Marietta, Saudusky, Osage, Ozark, Neosho, Unipqua, Win- nebago, Milwaukee, Chickasaw, and Kickapoo. The Keokuk fixed turrets had one 11-inch in each. The Onondaga had two short 15-inch and two 150-pounder Parrotts. The New Ironsides had a covered battery of 14 11-inch and two 150- pounder Parrotts. The Dunderberg was pierced for 16 guns, but never carried more than two 15-inch (long) and four 11-inch in battery. CHANGES IN THE BATTERY. The query includes guns that have been carried, as well as those which are now carried. I have to state that two of the Monadnock's 15-inch Nos. 24 and 27 (both short) were surveyed, condemned, and sold, (December, 1865,) and replaced by two long 15-inch Nos. 82 and 86. One 15-inch in the Miantonomah has been ascertained, after her return to the United States, to be bored four inches too deep, and is, therefore, condemnable, and must be replaced. The Saugus's short 15-inch (No. 29) was split, and replaced by another, (No. 57 long.) The Patapsco's rifled 150-pounder Parrott, No 6, was cracked in action and replaced by No. 40. The second gun, No. 40, was also cracked, and replaced by a third, No. 35, which was on board when the vessel was sunk by a torpedo at the entrance of Charleston harbor. The Lehigh's 15-inch, (short,) No. 13, was cracked and sold, being replaced by No. 16, (short.) The Passaic's 11-inch was replaced in 1863, at New York, by an 8-inch rifle no defect in the 11-inch. The Montauk's short 15-inch, No. 4, and 11-inch, were replaced by 15- inch, Nos. 56, and 80, (both long guns.) It does not appear that these guns were displaced on account of defects, but only to make way for two long 15-inch. The length of the first 15-inch, designed by myself, was much reduced in order to accommodate it to Mr. Ericsson's method of firing with the muzzle inside the turret 5 which was intended to avoid cutting the large EXPERIMENTS ON HEAVY ORDNANCE. 125 apertures in the turret that would be necessary for the muzzle of the 15-inch, if they passed through the wall of the turret so as to be outside when fired. The firing inside made it necessary to box the muzzle so as to exclude the smoke, and it was found that these boxes were liable to be disabled frequently in action by the excessive shock of the discharge. 15-inch guns were, therefore, cast of greater length, so as to pass out- side the turret, and were reduced at the muzzle so as to have the aper- ture as small as possible. In doing so the gun was made too thin at the extremity of the chase. I drafted the original navy 15-inch gun; the responsibility of the modified draft has been assigned to the Chief of the Bureau of Ordnance. (See memorandum Report of Committee on Ordnance, p. 131.) The total number of guns now or at "any time mounted in iron-clad ships of this navy," as given in the preceding statement, may be summed thus: Short 15-inch, 27; long 15-inch, 33; 11-inch, 98; 150-pounders, 16. Reply to query 2. THE 15-INCH GUN. The circumstances under which this class of gun was brought into our naval service were so urgent and abnormal as to impose on the bureau the necessity of some deviation from the formula usually prescribed in respect to a trial gun as a basis of reception from the founders. The extraordinary efforts of the rebel government had enabled it to precipitate an iron-clad ram upon our blockading force in Hampton Roads in March, 1862, which, being composed of wooden vessels, suf- fered severe loss from the attack, and would have been entirely destroyed the next day if the Ericsson monitor had not providentially arrived in season to frustrate the further progress of the ram. The moment was critical, for just then our army was on the eve of /moving upon Rich- mond, and the transports assembled in the Chesapeake for that purpose were endangered. The Navy Department satisfied, as it might well be, with the signal success of the monitor, immediately took measures to build a number of like model, but larger, so as to carry heavier ordnance ; the choice of which the Navy Department itself assumed, and directed the Bureau of Ordnance to have cannon of 15-inch calibre made for the purpose. The bureau and myself represented to the department that there were strong reasons against this selection at the time, viz : A 15-inch gun must weigh between 40,000 and 50,000 pounds. Only one of the kind had been made, and its endurance tested, but with inferior charges. Our most experienced founders were therefore not practiced in the fabrication of such heavy cannon, nor, indeed; of cannon larger than the 11-inch, about one-third as heavy as the 15-inch. The accidental rupture of a 15-inch on board a monitor when in action would disable and might be fatal to the vessel. There was no time for deliberate experiment, the exigency of the coun- try demanding immediate decision. A gun of smaller calibre, say 13-inch, would be more reliable, and its shot of 280 pounds, driven with greater charges, would exercise destructive eifect on any plates which the rebels could oppose to our fire. In addition to which the lesser dimensions of the 13-inch would admit of its being fired outside of the turret. * * I can say now, after repeated experience in battle with these guns, and the various results derived from them, in other ways, that myjopinions, already stated as submitted to the Navy Department, have undergone no change ; the complications inseparable from firing inside or outside would alone have constituted sufficient objection to the J 5-inch if they had been as well understood as they are now ; and I believe that the question of a suitable cannon for monitors is still open for decision at some future day. 126 EXPERIMENTS ON HEAVY ORDNANCE. The department adhered to its selection, and it became the duty of the bureau to carry its directions into execution j the responsibility of drafting the gun was devolved on ine. The engagement between the monitor and the rebel ram took place on the 9th of March, 1862. On the 17th the department ordered the bureau to provide 20 15-inch guns and 10 20-inch, for the monitors to be built. On the 20th the bureau telegraphed an order to the Fort Pitt foundry for the casting of 15-inch guns, and on the 6th of April I had completed the draft of the navy 15-inch gun. There was only one foundry in the country prepared to enter immedi- ately upon the fabrication of cannon of such weight. The bureau had, therefore, no choice of terms, first in order and importance of which was the trial of a gun to extreme proof ; but the founders were not willing to submit to other proof than that ordinarily required by the army ordnance for each gun, viz : the firing of three rounds with 50 pounds and a shell, and intimated that they would suspend the fabrication until these views were assented to. An appeal was made by the bureau to other foundries, with the follow- ing result : Date. July 11,1862. Aug. 20, 18 . Aug. 20, 186-2. Aug. 20, 1^62. Aug. 20, 18'" 2 Aug. 20,18 2 Aug. 20, isr.2. Names. Foundry. R. P. Parrott | West Point . Z. Chafee j Providence - . Juo. Sparrow Portland Co. Mathews & Moore . . . . j Philadelphia ' Hinkley & Williams.. j Boston...' Seyfert & McManus..| Reading A er ^ Co . . Boston . . Reply. July 18, 1862. Declined for the present. August 28,1852. Will accept conditionally. * August 26, 1862. Declined. August 30, 1862. Indefinite ; de- pends upon how many are wanted. August 23, 1862. Not prepared. August 21, 1862. Accepted. September 19,1862. Insufficient facilities, &c. The Reading foundry alone accepted; but as no immediate deliveries could be expected from it for the use of the monitors, (none did take place until April, 1865,) the bureau had no alternative but to submit to the terms of the Pittsbtirg foundry, and these, as already stated, there- fore constituted the " basis of acceptance" for the 15 -inch guns then under contract, which the bureau was obliged under the circumstances to consent to. But to guard the public interests against the calamity of accident in a monitor, the first 15-inch gun was ordered to be fired 50 more rounds at the proving ground, and then sent to Washington for extreme test. With all the despatch that the founders could use the first naval 15-inch was not ready when the first monitor (Passaic) had been launched and required her armament, (30th September.) When the second 15-inch had been completed and mounted in the Passaic (October 20,) the proof of the first gun had advanced to 220 fires. It now became evident that two 15-inch guns could not be supplied to any of the monitors then being finished, and hence an 11-inch was asso- ciated with a '15-inch in each turret. With this armament the first squadron of monitors went through the active service of the co-operative campaign against the defences of Charleston, in 1863. EXPERIMENTS ON HEAVY ORDNANCE. 127 When all the circumstances are considered under which the naval bureau of ordnance accomplished this task, the extreme and immediate necessities of the Union cause for iron-clads, the unprecedented size of the 15-inch guns, the absence of all the customary data and experiments whereby the bureau could guide its action, the fatal injury to the Union cause if even a single gun of those placed in the monitors should give way in any battle I say when all these are considered, it will be con- ceded that no ordnance authority had ever been submitted to a like respon- sibility, nor received less credit for the judicious and successful manner in which it acquitted itself of that duty to the country in those years of sore need, 1861, 1862. THE 15-INCH G-UN. The basis of acceptance for this gun for use in turrets was its estab- lished character in the service, and the tests to which it had been submit- ted to that end, viz: One trial gun burst in July, 1855, and another April 18, 1856. RIFLE 150-POUNDER. I This gun was brought into the navy under circumstances as exigent and extraordinary as the 15-inch, with even less substantial data to pro- ceed on. So far as such heavy rifled calibres were concerned, the bureau had scarcely a well-assured fact for its guidance at a time when the towering strides of the rebellion were tasking the utmost efforts of the Union gov- ernment, and demands beset it on all hands for these very cannon. Just before 1 took charge of the naval bureau of ordnance, in July, 1862, my predecessor apprised the Navy Department (July 10, 1862) that The investigations on the subject for rifled cannon had hardly commenced at the breaking out of the rebellion. The imperative call for rifled guns from all the officers commanding vessels in the block- ading squadrons, and the rapid increase of the navy, obliged the bureau, as the department is well aware, to make use of every reliable expedient to meet the demand. It has not been possible, under the circumstances, to conduct experiments with the view to improvement in the deliberate manner which has characterized every important change in our naval ordnance. It may be proper to state, in this connection, that the ordnance author- ities of other countries were then in no better plight than ourselves in this respect. The Parrott 100-pounder may be said to date from the 28th of October, 1861, as it was then brought to the consideration of the Bureau of Ord- nance, as the tiles show that the first gun of that class had been taken to Sandy Hook for trial, and that another would be deliverable in a week. In March, 1862, the first 8-inch rifle (which is the piece used in tur- rets) was in condition for experimental test when it was fired 50 times. Under the necessity of a pressure more inexorable than any Ordnance Bureau had ever before to sustain, Captain Harwood, then chief of bureau, ordered two guns of this class for service, (April 12, 1862.) There was no time to await the course of deliberate and full experi- ment, and the bureau was compelled to commit the rifled 8-inch to the tests of service with such desultory and imperfect trials as the exigency permitted, and these must be considered to constitute the only basin of acceptance for the 8-inch rifle that was possible. 128 EXPERIMENTS ON HEAVY ORDNANCE. Reply to query 3. The extreme proof to which the test naval 15-inch gun was put may be given as follows, viz : Mammoth powder Cannon powder. 80 rounds of 30-pound shell of 330 pounds. 20 rounds of 35-pound shell of 330 pounds . 70 rounds of 40-pound shell of 330 pounds. 22 rounds of 45-pound shell of 330 pounds. 1 round of 50-pound cored shot of 400 pounds 49 rounds of 50-pound shell of 330 pounds. 242 20 rounds of 30-pound shell of 330 pounds. 377 rounds of 35-pound shell of 330 pounds. 4 rounds of 35-pound cored shot 400 pounds. 20 rounds of 40 -pound shell of 330 pounds. 1 round of 49-pound cored shot 400 pounds. 27 rounds of 45-pound shell of 330 pounds. 1 round of 45-pound shot of 427 pounds. 101 rounds of 50-pound shell ot 339 pounds. 1 round of 50-pound canister of 208 pounds. 20 rounds of 55-pound shell of 330 pounds. 21 rounds of 60-pound shell of 330 pounds. 2(5 rounds of 60-pound cored shot 400 pounds. 3 rounds of 60-pound solid shot 430 pounds. 2 rounds of 65-pound cored shot 400 pounds. 2 rounds of 70-pound cored shot 400 pounds. 626 242 Total 868 I . The above is the report rendered January, 1869, upon a call from the bureau to correct discrepancies in former reports. It is to be observed that the mammoth powder is inferior in strength to the cannon powder used by the navy in all heavy guns. The exact relation of strength cannot be given now for want of pre- cise data. I directed some practice for range in order to obtain an approxima- tion for the information of the committee $ it resulted that the mammoth powder gave only 960 (average) yards from a 9-inch gun at an elevation of 3 27', whereas the range with the standard powder gave 1,325 yards. Besides this greatly decreased power, the ranges were very irregular ; extreme difference 209 yards, showing irregularity of action in the pow- der. It is to be remarked, however, that the powder had undergone . some handling, and perhaps exposure. Other powder, of undoubted quality, will be obtained and tried. The practice for range was resorted to, as the ballistic pendulum hap- pened at the time to be temporarily out of adjustment. The ordinary proof of the first 34 15-inch cannon, to make them receivable from the founder, was the army-proof required by Mr. Knap, viz : three charges of 50 pounds of powder (mammoth) and one shell of 315 pounds. In addition, before mounting in service, the bureau ordered 25 rounds of service charges, viz: 30 pounds powder (ordinary) and one shell of 330 pounds to be fired. The ordinary proof fixed for the last 66 15-inch guns was three fires with 35 pounds and shell ; three with 45 pounds and shell ; and three with 55 pounds and cored shot of 400 pounds. EXPERIMENTS ON HEAVY ORDNANCE. 129 THE 11-INCH GUN. The first 11-inch gun was fired 1,959 times, when it burst, viz 506 times with shell of 132 pounds. 655 times with shot of 170 pounds. 798 times with shell of 132 pounds. 1,959 The charge was in all cases the service charge of 15 pounds, except in nine instances with 10 pounds, and seven times with 5 pounds. This gun manifested an extraordinary quality of metal ; it began to exhibit cracks about the chamber early in the proof; these extended gradually from the chamber into the bore, and at the 1,958th fire the crack extended from the inside to the outside, showing a length of 24 inches on the outer surface, from the vicinity of the vent forward along the cylinder ; but the gun remained whole, and I deferred the last charge until Mr. Alger, who cast the gun, could witness this singular instance of tenacity. The gun was then loaded again and burst into three pieces; the line of fracture separating the body of the gun lengthwise, and the chase breaking off outside the trunnions. THE 8-INCH 150-POUNDER. The proof gun of this class was fired 420 times, when it burst, viz : Sehenkl, (shot,) 50 rounds, 194 J pounds, ") Parrott, (shot,) 21 rounds, 172 pounds, ! charges, 15 pounds navy Schenkl, (shot,) 263 rounds, 194J pounds, [ powder. Hotchkiss, (shot,) . 86 rounds, 199 J pounds, J 420 It is due to Mr. Parrott to say that he complained of the use of other shot in his gun than those for which he designed it, and that he had protested against the use of any other, (November 14, 1862 ;) also that his term for the gun was " 8-inch rifle, 77 and that in speaking of it as a 200-pounder, he only conformed to the nomenclature of the ordnance department. (See article 390, page 102.) On the other hand, the bureau considered that the use of different shot might be compulsory or desirable ; and it was therefore its policy to know the capacity of the gun to endure such as were in common use. However, taking into consideration the points presented by Mr. Par- rott, it was plain that the gun would have endured longer with 150 -pound shot than with shot of 200-pounds ; it might be also that the Parrott shot would strain the gun less than other shot. The endurance, therefore, of the 8-inch rifle was to be accepted at a higher rate than 420 fires, and conformably to the preference of Mr. Par- rott the weight of shot was fixed at 150 pounds, and the gun was (by general order) named an 8-inch 150-pounder rifle. The ordinary proof of each 8-inch rifle of this class has been 10 rounds with 16 pounds of powder and a shell of 139 pounds. Reply to query 4. I am not aware that any calibre used by the navy has been adopted from the tests, proofs, or experiments of the army ordnance by the naval Rep. No. 266 9 130 EXPERIMENTS ON HEAVY OEDNANCE. bureau of ordnance, excepting that of the 15-inch, and then in that case the responsibility, model, and design of the gun were placed upon myself and were made to conform to those of the 9-inch and 11-inch guns of the navy, except in length, which was reduced so as to suit the limited space of the monitor turrets where they were to be placed. The only essential particular in which the army experience was con- sulted was the mode of casting the 15-inch 5 and it is easy to see that under the circumstances this was unavoidable. 15-inch guns had been ordered by the Navy Department for the monitors then building ; the foundry where the first 15-inch had been cast-, being the only one capable of such work at the time, had received the order to cast the navy 15 inch, and the proprietors of the foundry were also proprietors in part of the patent for hollow casting; there was no time to ascertain by trial what treatment of iron was proper for such unusual masses of metal if cast solid, and the only gun of the kind that had been made was cast hollow. I believed that the public interests required me to use the same means that had been adopted for the trial 15-inch gun for the army even at the cost of some strain on my own convictions. I did not hesitate, there- fore, at the seeming sacrifice of these convictions, with the express res- ervation, however, that the hollow casting should be used no longer than the occurrence of the opportunity to investigate the other method fully by experiment. On the other hand, in reply to the second branch of the question, the army ordnance is infinitely more indebted to the navy for the principle of the present model, on which its heavy cannon are now constructed. This is contested I know; it is denied by General Rodman that the models of the army cannon are similar to those of mine, and in this he is supported by other officers of the army, as the committee may observe from the opinions already in testimony before them. (See report of heavy ordnance, February 13, 1365; testimony of Generals Ramsey, page 9, and Barry, page 51 ; Captain Mordecai, page 56 ; and Mr. Knap, page 85.) But there are other officers of the army who do not agree that the models are different, viz: Captain Benet of the army ordnance says, page 37: The outline of both guns is pretty much the same. Colonel Benton of the army ordnance says, page 69 : I do not think there is any essential difference, however, in the two forms. (Another part of his testimony is not entirely consistent with this.) Besides, Mr. Parrott says, page 144: I believe Captain Dahlgren thinks the army have taken the models of his guns, as the columbiads are made essentially as the Dahlgrens were. I am not alone, therefore, in my opinion as expressed above, and am convinced that the plainest judgment will recognize the entire similarity of model by placing draughts of the army guns alongside of mine ; and if to these be added the draughts of the old models those which the hollow casting failed to make reliable I think the judgment will be assisted by the comparison. No other instance of importance occurs to me just now where either bureau has been indebted to the other in the way referred to by the query of the committee ; nor would such be likely to arise often, in view of the very different applications of ordnance which are made by the army and navy, and the great dissimilarity of conditions to which each is subject. The requirements of sea and land service differ too widely to admit of there being much in common in the choice of artillery and its appliances. EXPERIMENTS ON HEAVY ORDNANCE. 131 The business of both bureaus makes cannon their specialty; but while light artillery is an essential constituent of a military organization, it is a mere incident to naval operations, employed only in boats or where small bodies of seamen are landed, and has no part whatever in the legitimate purposes of a navy that is, ship against ship. On the other hand the heavy cannon is the true almost the exclu- sive weapon of a ship of war employed in her proper business, singly or in fleets, while the campaign of a long war may be carried on with- out firing a shot of heavy calibre. During the war of the rebellion I am not aware that the army ever fired a shot in action from a 15-inch gun ; and even 10-inch guns and 8-inch rifles were sparingly used, while the heavy cannon of the navy resounded along the Mississippi and the Atlantic shores from the batteries of Far- ragut and Porter, Foote and Dupont, and were echoed back from the British channel by the 11-inch guns of the Kearsarge. I have no idea of saying that the army have no use for heavy cannon, but that as a general rule such use will not be frequent. Again, the conditions under which heavy cannon are to be used ashore or afloat, very widely and essentially influence their weight, dimensions, and appliances. The gun which is to be used in a fort may be as heavy and as long as may be deemed best for its efficacy. Not so in a ship ; the weight of cannon is regulated by the capacity of the vessel to carry, or of its decks to bear ; and the length by the space that is available ; (particu- larly was this experienced in the 15-inch guns for the monitors.) Some- times these conditions may conflict ; there may not be space for all the guns a ship can carry, nor capacity to carry where there is abundant space. Then there is the problem of armament in pivot or in broadside. Who can decide such questions, or discuss them, but men experienced as seamen and as ordnance officers? It could hardly be the province of a soldier. Quite as much special nautical aptitude is needed to determine the carriages for sea artillery. Ashore the handling and pointing of a heavy gun where the platform is fixed and space abundant, is comparatively a small matter to the accomplishment of a like purpose on shipboard, where every kind of motion is to be provided against. A great difference of construction at the breech also occurs between heavy cannon for forts and for ships, occasioned by the use of breech- ings for the guns of the latter, which are never used in the cannon mounted on fortifications. And who, if not a sea officer, shall decide on the kind of gun carriage to be used in boats, or for landing from boats, and subsequently ashore? On the other hand, how shall a naval officer possess himself of the information and experience to fit and equip the peculiar appliances of field artillery, the carriages, caissons, horses, harness, all the multifari- ous details of that splendid arm ? It would not be possible to unite in any corps of men from the army or from the navy the knowledge and experience necessary to conduct the ordnance business of both, from the design and fabrication of cannon and its accessories through all the details for service. The results obtained in England and France from a consolidated organization offer us nothing that should tempt us to an imitation of their example. The British organization, unable to keep pace with the feverish appre- hension of the public, was subjected to an entire change. The direction was taken from the regular authorities and handed over almost in fee 132 EXPEEIMENTS ON HEAVY ORDNANCE. simple to the autocratic control of a scientific civilian, one of the most accomplished engineers in England ; he was rewarded in advance with knighthood and a princely gift. What was the result? After several years of untrammelled effort and the expenditure of $15,000,000, (in gold,) all the heavy Armstrongs were altered or dismissed from service, ashore and afloat, the inventor's plans exploded and himself unseated. Eng- land cannot to this day feel sure that she is in possession of a heavy rifled cannon that is to be relied on. France is believed to be no happier in the results of her ordnance department and I think I have seen in service the most recent of them. Reply to query 5. I am at a loss to reply to this query as the committee may intend that I should. To do so completely, in the broadest sense, would require the examination of a large quantity of reports and correspondence accumu- lated from the commencement of the rebellion, which will include by far the greatest number of 9-inch and 11- inch cannon now in the navy, all of the 15-inch cannon, all of the rifle cannon of heavy calibre, and all wrought-iron guns submitted to inspection or received. This has been commenced, but at this date I have accomplished but a small part of the task. With the permission of the committee, I will therefore reply in a briefer manner, which may perhaps meet the purposes of the committee. As regards cast-iron guns, the least crack, external or internal, would cause immediate rejection at sight ; therefore no founder would knowingly ever offer such a gun for inspection. Cavities occurring in the bore or cham- bers of cannon will cause their rejection on sight, and on the outside also if they exceed certain dimensions. As a sample of the exact adher- ence to terms required of founders who have contracted to make cast- iron cannon for the navy, and of their ready compliance therewith, I give the following extract from the record, viz : 11-inch, Reading foundry, November 10, 1862. Not proved. After bor- ing and while turning an indentation or defect discovered having the appearance of a slight scratch. On probing it, the unsound part extended to the depth of T 3 ^ inch less than the prescribed dimensions. Caused by the inferior quality of the sand, having a tendency to swell under the heat. Gun rejected. Location of defect, upper part of chase forward of lock lugs. Two guns, 11-inch, Reading foundry, November 16, 1862. Not proved; same defect from same cause as above. Guns thrown aside by contractors. It is due to the contractors to say that they have rarely complained of the exact nature of the inspection and the losses to which it subjected them. No appeal from their bargain has ever been made or thought of by them. Besides cracks of this kind, the hollow-cast guns seem to be liable to others peculiar to themselves, though I am not able to say whether these casualties are of frequent occurrence. The record notes the following: 15-inch, No. 404, Reading foundry, army gun. Burst open nearly the entire length of the gun, while in the heading lathe, with a loud explo- sion equal to the report of a 6-pounder. 15-inch, No. 419, Reading foundry, army gun. Burst in the pit after removal of core barrel, and while cooling the bore with water conducted through it at the rate of 18 gallons per minute. 15-inch, (no number,.* Fort Pitt foundry, navy gun. The inspector in his weekly report states that one 15-inch gun cast on the 6th instant has been condemned by the founders, the gun having burst while cooling. EXPERIMENTS ON HEAVY ORDNANCE. 133 Reply to query 6. To answer this would require sufficient time to collect the facts from a record largely accumulated during the rebellion, which the conveniences of the committee does not permit. It would include every cast-iron gun which was proved or fired so far as to exhibit cracks or signs of rupture, and was then permitted to remain in that condition without being burst. I will therefore reply as well as I can to this query in a general way. All fissures or cracks which appear inside or outside after firing will cause the rejection of any cast-iron cannon. Interior cracks may appear in cast-iron cannon, and will often continue to extend for a large number of rounds before bursting, provided the metal is of the least respectable endurance ; the line of rupture will also in such cases take the same general direction, at least in the present models. But when the metal of the gun has been very bad originally, or has been rendered so by im- proper treatment, or by bad model, and has no endurance, the gun will break up in fragments after very little firing. The experience with heavy wrought-iron cannon is not sufficient to define the law of fractures occurring in such material ; it may be that cavities, cracks, or even fissures, do not imply a liability to rupture as imminent or dangerous as in cast iron. But it requires much experiment to determine to what extent these defects may extend without rendering the gun unserviceable. Wrought-iron cannon, like that on the Princeton, for example, have burst as suddenly and as fatally as guns of cast iron, and others have endured severe tests after the appearance and extension of cracks in the bore. The same may be said of some cast-iron guns. The first 11-inch gun withstood 1,000 rounds after it began to crack inside; and the crack pene- trated entirely to the outer surface for a length of two feet in the rear of the trunnions without breaking the gun open; the next fire however, did so. I have noted in replies to other questions of the committee some information which might be repeated here, and to which I beg leave to refer. This reply is very incomplete, owing to the want of time to scruti- nize the reports of firing and inspection of wrought and cast guns. Reply to query 7. 1827. The regulations of this year for naval ordnance, " adopted by the board of navy commissioners," Commodore Bainbridge, president, prescribe the following for proof of the heaviest cannon by powder: Weight of gun. Proof charges. 42-pounder heavy Cwt. 7U Pounds. 21 ) Equal to one-half 32-pounder heavy 60 16 > the weight of 24-pounder heavy 49 12 N solid shot. Each gun was to be fired twice with these charges, and two shot with three wads, one being placed over the powder, another over the first shot, and another over the second shot. If, after this proof, any defect appears which occasions doubt of safety for general service, this proof is to be repeated. 134 EXPERIMENTS ON HEAVY ORDNANCE. 1845. The next instructions concerning proof of "cannon are found in the ordnance regulations of 1845, when an entire reorganization of ordnance was adopted, adopting one calibre for all shot guns that of 32 and fixing three classes of shell guns, a notice of which will be found in my work on " Shells and Shell Guns." In these the Bureau of Ordnance received discretion to have a 9- pounder cast as a model gun, which was to be proved as follows : No of rounds 20 j powder 3 pounds ; shot, 1, &c., &c., &c., until the gun breaks. The proof charges of the heaviest guns were : Powder. Shot. 10-inch 10 000 pounds Pounds. 18 1 8-inch 10,000 pounds 18 2 8-inch of 63 hundred -wei ght . . ... . 18 1 8-inch of 53 hundred- wei ght . ... t 14 1 32-pounder of 61 hundred-weight 16 2 32-pounder of 57 hundred- weight . 15 2 Each gun to be fired twice. If one gun in every ten failed to sustain this proof, the remainder were to be fired again with the same charge and one shot, if two had been used before, and with three-fourths the charge if only one shot had been used before. If one gun in nine failed to stand this proof, all that had been proved were to be rejected. The board included Morris, Warrington, Crane, Wadsworth, and Shubrick. It is presumed that this was the usage is 1850. In 1852 a more elaborate series of ordnance instructions was promul- gated by the bureau. In these the chief of bureau "may, if lie thinks proper, have a trial gun cast therefrom* which shall be subjected to such proof as he may direct and specify in the contract." The proofs were to be : Powder. Shot. 10-inch of 10 000 pounds Pounds. 18 1 8-inch of 63 hundred-weight 16 ] 8-inch of 55 hundred- weight . . 14 1 64- pounder of 106 hundred- weight .. ... 20 2 32-pounder of 6J hundred-weight 16 2 32-pounder of 57 hundred-weight 15 2 Each gun to be fired twice. First. It will be observed that it still remained discretionary with the chief of bureau to order a trial gun or not. Second. That he was restricted in kind or size as before. Third. That the proof of the 8-inch of 6,300 pounds was reduced from 18 pounds to 16 pounds 5 that the 8-inch of 10,000 pounds disappeared and was replaced by the heavy 64-pounder, (an 8-inch cannon,) of 10,600. *Iron offered by contractors. EXPERIMENTS ON HEAVY ORDNANCE. 135 It is to be supposed that this continued to be the proof in 1855. The officers of the board were, Farragut, Dornin, Barren, Harwood, Fairfax Commodore Morris, chief of bureau. In 1860 the ordnance instructions were revised. No directions are given in regard to the inspection and proof of cannon. The 9-inch, 10-inch, and 11-inch of my design are there announced as part of the regular armament. The officers of the board were, Goldsborough, Harwood, Lee, and Fair- fax Captain In graham, chief of bureau. 1864. First. The instructions of this date give discretion to the bureau before contract, to order a trial gun for extreme proof with service charge. This gun was to serve as a standard for metal to be used. Second. "But whether a trial gun was made or not," the chief of bureau might select "for extreme proof with service charges," one out of any lot of guns offered under contract. Third. Proof charges : Fifteen-inch, No. 1, 50 pounds, cored shot ; No. 10, 35 pounds, shell. Eleven-inch, No. 1, 25 pounds, shot ; No. 10, 15 pounds, shell. Ten-inch, No. 1, 18 pounds, shot ; No. 10, 12 pounds, shell. Nine-inch, No. 1, 15 pounds, shot ; No. 10, 10 pounds, shell. Eight-inch, 6,300 pounds, No. 1, 12 pounds, shot j No. 10, 10 pounds, shell. One-hundred-and-thirty-pounder of 16,000 pounds, No. 10, 30 pounds, one shot. Sixty-four-pounder of 10,600 pounds, No. 10, 20 pounds, one shot. Thirty- two-pounder of 5,700 pounds, No. 10, 15 pounds, one shot. If five per cent, out of any lot offered for ordinary proof under a con- tract shall fail to sustain it, the whole may be rejected, as may be stipu- lated in the contract. These, it is presumed, were the rules in 1865. 1866. The instructions of this year fix the proof charges as follows : Fifteen-inch, No. 3, 35 pounds, shell ; No. 3, 45 pounds, shell ; No. 3, 55 pounds, cored shot. As in 1864, the failure of five per cent, in a lot gave discretion to reject all. The instructions of each date are to be accepted as a recognition of the operations and practice then adopted. The practice of proving cannon by increased charges of powder and shot prevailed prior to 1827, and continued to 1845, with the addition, at the latter date, of a trial gun of 9 pounds calibre, proved previously by specified charges 5 and this was the only improvement on the previous system $ and this was not enjoined, but was discretionary. 1852. In 1852 the trial gun was still retained as discretionary with the bureau, and no calibre being assigned, that too thus became discretion- ary also, so that he was empowered to have the trial gun of any calibre, and to prove it in any way he thought proper. I860. In the instructions of 1860 all mention of proof or inspection is omitted. Important changes had taken place. Our new screw frigates and sloops were armed, according to my own system, with Dahlgren 9-inch, 10-inch, and 11-inch guns, and these guns are given in the instruc- tions as of regulation. In fact, with these, other views of proof had come. I had always been opposed to the principle of proving any gun with more than a service charge. The proof gun was always to be one of the kind to be proved, and its proof was to be service charges till burst. The ordinary proof for each gun might be a small number of service charges, 10 or 20, but the bureau still retained a large number of guns of the old system in service, and hesitated to apply my views to it ; so nothing was said, which may be the explanation. 136 EXPERIMENTS ON HEAVY ORDNANCE. 1864. This year my own views are accepted. The bureau was author- ized to use a trial gun to fix the standard, and also to select a gun from a lot for extreme proof, with service charges. In addition, as the question of hammering plating was presented, and the guns were to use higher charges, therefore the ordinary proof added one service charge of that description. 1866. The same is retained, except with 15-inch guns. The proof to extreme, being at the discretion of the bureau, has been fixed at 1,000 rounds (service) in the contracts. Reply to query 8. It would be impossible for me to answer this question fully and cor- rectly within the very limited time which the convenience of the com- mittee permits, as it would necessitate the close examination of a large number of log-books, besides the numerous records of this bureau. I will only be able to submit a few desultory and disconnected facts, premising that they are insufficient to form a proper opinion. When the first 15-inch gun was being put through a course of proof- firing I was absent, or too closely occupied with other duties to be present. The record is very general, noting only the principal facts. While in command of the South Atlantic squadron I was frequently on board the monitors in action, and therefore witnessed the general character of the firing, but my attention was always too closely taken up by passing events to time the rate of fire. The impressions on my mem- ory are that it required five to six minutes for each shot from a 15-inch gun, and this is all that I can say with reference to the rapidity of fire that was attained in action by 15 inch guns of monitors, mounted on the carriages in their turrets, the machinery of which was worked by hand. In the spring of 1868 a 15-inch gun was tried upon a carriage worked by steam, after the design of Mr. Eads. The most rapid fire was the discharge of 12 shot in 16 minutes, making an average interval of one minute and 20 seconds between the fires, which is certainly an excellent result ; one interval was as small as 58 seconds. Still it cannot be com- pared with the result of ordinary fire in action cited previously, because there was a very essential difference in the circumstances. When fired ^irom the monitor turret the 15-inch gun was not only loaded, but the turret was revolved from the object, then back upon the object, to which it had to be adjusted by one person who did not see the object, but received direction from another who did see it, yet very imper- fectly, through a tube at the side, and was also delayed by the swaying of the vessel, whether at anchor or under way ; all of which, under the most favorable circumstances, would occupy at least half of the five or six minutes. On the other hand, the interval of one minute and 20 seconds, accom- plished by the steam apparatus and carriage, only denoted the time required to load and fire ; the carriage was placed on a scow ; the gun horizontal, and not pointed. The difference between firing in service and in experiment is also con- siderable, even where circumstances are otherwise similar. On one occa- sion a 9-inch gun was fired from the experimental battery four times, with an average interval of 53 seconds ; least, 45 seconds. On another a 9 : inch gun of the experimental battery was fired six times ; average interval, 38J seconds ; the least, 32 seconds. In another instance in exper- iment, an 11-inch gun was worked by eight men and fired twice, the interval being 61 seconds. But this rate of fire with such cannon would not be possible in action. EXPERIMENTS ON HEAVY ORDNANCE. 137 On the whole, I have no doubt the 15-inch gun can be fired more rapidly on the steam carriage than on one worked by hand, but what that difference is, how far to be relied on with certainty, and at what cost in other advantages, experiment alone will show, and should be made to show. Reply to query 9. The navy has never used a Parrott 10-inch rifle. I have no informa- tion as to the rapidity of fire with Parrott 8-inch rifles. In general, more time is required to load a rifle-cannon of large calibre than a smooth-bore, the weights of shot and charge being alike. Reply to query 10. All the information upon this subject that can be reached within the time admissible to prepare this paper has been given in the reply to query 8. Reply to query 11. THE NAVY 15-INCH GUN. There being two classes of the navy 15-inch gun the short and the long and a large proportion of the original cannon made after my draught having been altered, the question of the committee will be best answered perhaps in the following way: The navy 15-inch guns may be classed thus : 1. The original 15-inch designed by myself. 2. Guns of the same class, subsequently altered by order of the bureau. 3. The new model 15-inch, got up by direction of the bureau. The original navy 15-inch was designed by myself, and, conformably to the wishes of Captain Ericsson, was restricted to such length as would permit it to be fired inside the turret. Thirty-four guns were made in accordance with this design, one-half of which were subsequently increased in the chamber and decreased outside at the chase by order of the bureau. Of the 16 15-inch which were not altered but remained as designed by me, the service of two is only known to have been very good, one having been lost in the Weehawken, and the other sold from the Lehigh. The remaining 14, with the proof gun, endured 3,152 fires, averaging 210 rounds, the greatest being (No. 1) 622, and the next 529. Of the 17 15-inch guns, made after my design and not altered therefrom, the proof gun was burst by 868 charges, and three were injured prema- turely by service firing, viz : ORIGINAL 15-INCH, (SHORT.) No. Rounds fired. On board. 'Condition . 19 132 Onondasra - ...... .... Cracks at vent. 13 Unknown Lehigrh . Muzzle cracked, (sold.) 14 96 Onondaga Cracks at vent. Seventeen other 15-inch guns of my model were altered by the bureau by reaming out the chamber and reducing the chase. They have been fired in all 2,266 times, averaging 135 fires, the greatest being (No. 34) 363 fires, and the next (No. 23) 358 ; both are reported to be in doubtful condition. 138 EXPERIMENTS ON HEAVY ORDNANCE. Of the whole number, eight have been more or less injured by firing, as follows, viz : No. No. of fires. On board. Condition. 19 351 Reports contradictory. 0^ 358 Cauonicus Reports contradictory. *M 168 Monadnock Excessive wear (sold ) 05 9 Sold at auction Cracks at vent k >6 9 Sold at auction ................. .... Cavities in chamber. 07 161 Monadnock . ..... . ... Condemned, (sold.) oq 243 Sauo*us Burst at chase Fort Fisher. 31 363 Doubtful As a memorandum before your committee has given the reasons for altering my design of the navy 15-inch gun, I presume it is admissible for me to examine how far these reasons are sustained by the evidence given. The memorandum says, (Heavy Ordnance, page 129,) that It was found necessary to reduce the opening of the ports in the turrets as much as possi- ble, and to permit the muz/le of the gun to protrude through them, thus doing 1 away with the troublesome smoke-box hitherto used, and which was indispensable with the shortened 15-inch gun originally designed. During this dilemma it also became apparent, from repeated results with the " teat cham- ber," that it was not only most inconvenient in service, but it really hastened the rupture of the gun instead of preventing it. It thus became necessary to act, and promptly too. Therefore the present Chief of the Ordnance Bureau ad interim directed the first 15-inch cast for the navy, and which was then undergoing a series of experimental firing at the ord- nance yard, in this city, to be placed upon the lathe, the teat chamber reamed out, so as to leave a chamber nearly parabolic in form, and to reduce the diameter of the chase and muz- zle to correspond with that of the model of the 13-inch gun. The result was most satisfactory; the gun enduring heavy charges of 50, 60, and two of 70 pounds of ordinary cannon powder, with shells and shot, the latter weighing 440 pounds, and did not give way until it had reached nearly 900 rounds. The order was immediately given to rechamber and turn down in the same way all the original 15-ineh guns, and to cast, as soon as possible, a lot of these guns on the new pat- tern. Now the facts of the case may be summed thus : 1st. The first 15-inch gun, as I designed it, was fired 622 times, with charges varying from 30 pounds of mammoth powder to 50 pounds of cannon powder. 2d. After this the teat chamber and vent were reported to show only the usual wear. 3d. The teat chamber was then reamed out to a parabolic form by order of the bureau, and the extremity of the chase reduced in diameter to that of a 13-inch gun. 4th. The firing was resumed and carried to 246 rounds, with charges varying from 45 pounds of mammoth to 70 pounds of cannon. At the 246th fire the gun burst. (See reply to query 3.) The Ordnance Bureau deemed this result so satisfactory that it ordered all the 15-inch guns at hand to be reamed out and reduced as the proof gun had been. Was this action of the bureau in altering the 15-inch warranted by the facts of the case f The bureau makes its reasons for altering the model to rest on the premise that the teat chamber hastened the rupture of the gun. Now does this appear to have been justified when the teat chamber was perfectly sound after 622 fires, and no sign was then perceived indi- cating rupture, or even weakness ? EXPERIMENTS ON HEAVY ORDNANCE. 139 If either chamber is chargeable with the hastening the rupture of the gun it must have been the parabolic, for with that the gun gave way after 246 rounds. The true conclusion after 622 fires was that a gun which endured so well ought not to have been altered at all, but should have been tested to the end in its original construction, and no "change was warranted even in the other guns that had been cast, unless the extreme proof of another gun of the class had shown better endurance, and there was sufficient reason to believe this to be due to the alteration that had been adopted, whether in chamber or elsewhere. Is not this view fully sustained by the subsequent results with these 15-inch guns, altered and unaltered I Of the 17 on the original model only three were unserviceable after firing 3,152 rounds. Of the 17 that were altered, eight were unserviceable after firing 2,296 rounds. To my mind there is but one conclusion possible : my original design was not improved by the alteration made by order of the bureau, in the guns that were cast, but was injured thereby. Let us now consider the other question which forced itself upon the consideration of the authorities. The memorandum says : It was found necessary to reduce the opening of the m ports in the turrets as much as possible, and to permit the muzzle of the gun to protrude through them, &c. The reading of this does not seem to express what it really intends, which I understand to be, the firing from the inside of the turret was found to be so troublesome in service by reason of the smoke box, which was indispensable to the practice, as to make it necessary to pass the gun through the turret 5 but as the chase-diameter of the 15-inch would require too large an aperture for this purpose, it was reduced, and the original model was altered, increasing the length of the gun, and reducing the diameter of the chase to that of a 13-inch gun, by which improvement the thickness at muzzle was reduced from the original five and three-quarter inches to three inches ; very little more than one-half of what I considered necessary for the incidents of service. There were 66 15-inch guns cast upon this pattern. The first gun was chosen for proof; it endured 131 fires, after which Commander Breese reported it to be doubtful. Of the remaining 65, 42 have been fired only the proof rounds, now fixed at nine. Twenty-five have been mounted in iron- clads, and been subjected to such firing as the course of service required, amounting to a total of 1,333 fires ; making an average of 53 fires for each gun ; greatest number (No. 43) 236 fires j (No. 37) 206 fires. Of these 25, four have been injured, viz : No. No. of rounds. Where fired. Condition. 35 131 Proof . . Doubtful 44 85 Mahopac . ...... ....... Ohase split 67 102 Puritan. - Cracks about vent, (sold.) 68 59 Trial of carriage Cracks about vent (sold. ) So that the original model lost only one-fifth of its number after its 17 guns had been fired 3,152 times. An equal number of original guns, after being altered, lost nearly one- half their number, though fired but three-fourths as often as the same number of original guns. The new model (long 15 -inch) lost one-fourth of its number, or nearly an equal proportion as the original model, though only subjected to two- fifths the firing, (less than one-half.) 140 EXPERIMENTS ON HEAVY ORDNANCE. The foregoing statements show that the substitution of a new cham- ber, and a reduction of the chase, in the original guns were detrimental to the strength of the guns ; they also show that the new model was not to be trusted in service. All the difficulties noted in the foregoing arose from pursuing a wrong- direction in the first instance. The department was advised that under existing circumstances a smaller calibre than that of 15-inch was prefer able, and that of 13-inch was suggested. The 15-inch was, however, adhered to, and the first consequence was to be met at the threshold; the chase diameters of the 15-inch were so great that it was found inadmissable to open a point in the side of the turret sufficiently large to admit of the muzzle passing outside. To obviate this it was necessary to abut the muzzle on the inner sur- face of the turret, and to .make an aperture in the turret only large enough for the passage of the ball. The first firing showed that the smoke would not be endurable when the gun was fired in this way ; the muzzle was therefore boxed, which proved effective ; but it was soon found that the box was liable to give way continually before the great concussion of firing, even with the very moderates charge used. The inside firing had therefore to be abandoned, and a port opened, but to make this possible the chase diameter must be reduced ; and so, instead of falling back on a proper calibre, the size of which would not require too large a port for firing outside, it was determined to reduce the chase of the 15-inch. This resulted in altering the guns of original model, and in the casting of others upon a new model ; the consequences of which have been shown to be highly injurious to the endurance of these 15-inch guns, if not absolutely destructive of their reliability. The memorandum argues against the adoption of the 13-inch gun, (page 131,) from the failure of those tried, the want of time for experi- ment, the necessity of firing outside, &c. 1st. Whatever were the defects of the inside firing, it was well estab- lished by the long-continued service off Charleston that it could be con- tinued in any further service for which the monitors might be required. If therefore the 15-inch was to be adhered to, it was better to fire inside and to take the chances of the smoke-box than to reduce the chase to an untrustworthy diameter. 2d. There was quite as much time to correct errors in the founding of 13-inch as there was to experiment with the 15-inch, which the altera- ' tions really amounted to. These errors were obvious, and needed only correcting, not experiment. It has been a primary principle in making cast-iron cannon that the larger the cannon the less was the probability (I might say the certainty) of its endurance. Therefore if a 15-inch gun could be made strong enough for service, a smaller gun like the 13-inch would be much more so, and a contrary result proved errors in the fabrication, the models being alike. The data cited by the memorandum point to this, and even with an error that exists in these data they should be conclusive ; for instance, the memorandum states that one of these 13-inch " did not give way at 500 rounds." Kow the entire actual service of the 15-inch shows that only one gun of this kind was fired more than 360 times, and that one gun went as far as 529 fires ; perhaps in no case did the charges exceed 35 pounds of powder, while the 13-inch was fired with charges of 50 pounds. It is EXPERIMENTS ON HEAVY ORDNANCE. 141 further to be remarked that these 13-inch guns were made at a foundry which for the first time essayed the process of hollow casting, and could hardly be expected to attain entire success at the outset. It seems to me that there was every assurance in this single result to show that 13-inch guns cast with as much care and experience as the 15-inch, would have more endurance than the 15-inch, while the size of the chase would need no greater size of port than was actually given to the reduced 15-inch. This course risked far less than that pursued by the bureau, which was an experiment against probabilities. The memorandum also goes beyond the question of calibres with its incidents, and enters upon the question of solid and hollow casting, taking for its premises certain data, which, even correctly given, would not, I think, lead to the conclusions of the memorandum, because the foundry at Providence was entirely without experience in casting cannon of any size, and its results were, therefore, not to be compared with those of another foundry, where the experience of years had been accumulated under special directions. On the contrary, I will affirm, from my own long experience, that the result at Providence was eminently successful. To make a solid casting of a 13-inch gun so well the first time that it stood 178 fires, is to me an assurance of entire success with more experience ; but an important error is made by the memorandum in stating that the 13-inch gun cast at Pittsburg was cast solid. It was cast hollow, and with all the lights of a long experience, yet it gave way at 108 fires. Shall we infer from these facts that a 13-inch gun could not be made as endurable as a 15-inch, the processes and the models being alike ? Shall we infer that the experienced founders at Pittsburg could only make a hollow-cast 13-inch to stand 108 fires, when foundries inexpe- rienced in hollow casting could make a 13-inch, also hollow-cast, that would not burst at 500 fires ? Shall we infer that the Pittsburg gun, cast after the hollow method so highly extolled,* (page 88, Heavy Ordnance,) would only endure 108 fires, when another of like model cast solid, by a founder who had never done such work before, would only burst at 178 fires ? Certainly not ; yet these would be the inferences, from the premises given and corrected, of the memorandum. On the whole I am unable to perceive that it was advisable first, to select the 15-inch for the monitors ; secondj to alter it, as was done, when it had been chosen ; and I think first, that the 13-inch gun was prefer- able because it could have been made more enduring than the 15-inch was, not too large to permit its being fired outside, and had sufficient power (50 pounds and shot of 280 pounds) to penetrate any plating opposed to us by the rebel rams ; second, that when the probable incon- venience of the 15-inch had been realized in service, the reasons for sub- stituting the 13-inch became imperative, instead of retaining the 15-inch and lessening such usefulness as it may have possessed by alteration. * Mr. Knap said: I would say, as my opinion as a manufacturer, and from my examination of these guns, that there is not known any method of procuring the same efficiency at the same cost and the same risk to life of your own men, as the heavy ordnance cabt upon the Rodman principle. You may take a cast-iron gun or wrought-iron gun, or anything else of very heavy calibre, and I will be willing to haug my gun alongside of it and let them, be fired, aud if mine fails before the others do I will give up. 142 EXPEEIMENTS ON HEAVY ORDNANCE. PARROTT RIFLE GUNS DISABLED. Calibre. Register number. Vessel. Remarks. 100-pound er 2 Hunchback Burst 23 inches from muzzle June 19, Do 4 Westfield 4864. Burst at breech and opened band in Do 6 Mahaska several places, October 31, 1862. Thirty-six inches of muzzle burst off; Do 11 Commodore Barney... date unknown. Muzzle burst off; shell exploded in Do 18 Genesee gun, April JO, 1862. Cracked in rear of bouching May, 1864. Do 21 Cimarron Burst 2"<i-J inches from muzzle Feb- Do. 24 Paul Jones ...... ruary 15, 1864. Burst, fracture from trunnion, to rear Do 05 Sassacus of band, July 18, 1863. Cracked ; two cracks at vent Janu- Do 29 Juniata ..... ary, 1865. Burst ; rear part flew out, December Do 44 Commodore Perry 25, 1864. Burst at breech June 17 1864 Do 135 Fort Jackson Cracked at vent January 14, 1865. Do 137 Quaker City Burst two and a half feet of muzzle off, Do 141 Mackinaw ....... December 24, 18(54. Burst ; breech blown out, December Do 149 Commodore Read 26, 1864. Cracked in top of bore and around Do 150 Commodore Read. breech, November 14, 1864. Cracked at bouching, November 14, Naugatuck . 1864. Burst. Do 162 Ticonderoga. ..... Burst at muzzle, November 14, 1864. Do 166 Yautic . Burst ; breech blown out, December Do 194 Maumee 24, 1864. Cracked through vent January 1865. Do 213 Kansas ... Cracked at vent, December 24, 1864. Do 233 Osceola Cracked ; two cracks from band to Do 238 Mendota ..... . trunnion, January 15, 1865. Cracked from trunnion to band, July Do 262 Tallapoosa 24, 1864. Muzzle blown off by premature explo- Do 288 Mohican sion of shell, April 5, 1865. Burst, December, 1864. Do 311 Ticonderoga Burst into 10 pieces December 24 Do 325 Lenape 1864. Cracked through vent Februarv 1865 Do 330 Lenape .... Cracked through vent, February, 1865. 150-pounder 6 Patapsco Slight crack at muzzle July 22, 1863 Do 28 Shenandoah Crack in rear of vent extending around Do... 46 Onondaga breech, February, 1865. Two cracks in bore. Do 59 Pequot Burst three feet ten inches from muzzle Do 60 Colorado September 12, 1864. Seam from trunnion to band Decent- Do 61 Onondaga ber25, 1864. Cracked at vent, April, 1865 Do 82 Susouehanna Burst ; piece of muzzle blew out June 15, 1865. TRIAL GUN AT CASTLE ISLAND, NOVEMBER, 1862. Four hundred and twenty rounds; charges 15 pounds of powder. Shot: Schenkl, 194 J pounds ; Parrott, 17?| pounds ; Hotchkiss, 199 J pounds. EXPERIMENTS ON HEAVY ORDNANCE. 143 WIARD'S 15-iNCH SMOOTH-BORE, (CAST IRON.) The first and only gun fired of this description burst June 4, 1864, at the first proof-fire ; charge 80 pounds of powder, and shot of 880 pounds. ERICSSON 12-INCH SMOTH-BORE (WROUGHT IRON.) The Ericsson (13-inch smooth-bore of wrought iron) was fired Octo- ber, 1864, 40 times, viz : Two charges of 30 pounds of powder, shot 280 pounds ; five charges of 35 pounds of powder, shot 280 pounds ; five charges of 40 pounds of powder, shot 280 pounds ; five charges of 35 pounds of powder, shot 280 pounds ; five charges of 50 pounds of powder, shot 280 pounds ; five charges of 55 pounds of powder, shot 280 pounds ; five charges of 60 pounds of powder, shot 280 pounds ; two charges of 65 pounds of pow- der, shot 280 pounds ; three charges of 70 pounds powder, shot 280 pounds ; three charges of 75 pounds powder, shot 280 pounds. Gun unserviceable. 12-INCH RIFLES. These were castings on the exterior form of 15-inch guns ; bored to 12-inch and rifled. The order was given August 31, 1863, by Captain Wise, then chief of bureau. One of these was rifled on Mr. Parrottfs plan, 'one on Atwater's, and one on Rodman's. The 12-inch rifled on Mr. Parrott's method burst at the 27th fire, viz : Five charges of 35 pounds of mammoth powder ; five charges of 40 pounds of mammoth powder ; five charges of 45 pounds of mammoth powder ; five charges of 50 pounds of mammoth powder ; five charges of 35 pounds of No. 7 cannon powder ; one charge of 40 pounds of No. 7 cannon powder ; three charges of 45 pounds of No. 7 cannon powder. The 12-irich gun, rifled on General Rodman's method, was badly cracked by 16 fires, viz : Three charges of mammoth powder, 35 pounds; three charges of mammoth powder, 40 pounds; four charges of mammoth powder, 45 pounds; four charges of mammoth powder, 50 pounds; one charge of mammoth powder, 35 pounds; one charge of mammoth powder, 40 pounds. Shot, 618 to 619 pounds. Gun cracked ; firing stopped. The third 12-inch rifled, on Atwater's plan, burst at the 30th fire ; generally 55-pound charges ; and shot varying from 416 to 535 pounds. The practice was conducted at Fort Monroe by the army ordnance, (1867.) DAHLGREN 150-POUNDERS. Only three of these were tested, and their accuracy was excellent, but the iron was not of sufficient endurance, therefore never put into service. One was burst in proof at the 27th fire ; one was fired 20 rounds ; one was fired 75 rounds ; one was fired 60 rounds. They remained unbroken ; but as I was not satisfied with the iron, they were never put into service, and the pressing events of the war cut short my connection with the subject. 144 EXPERIMENTS ON HEAVY ORDNANCE. Reply to query 12. The following 150-pounder cannon, and larger smooth-bore and rifled guns, have been the subject of proof or experiment in the navy: 1. The 150-pounder Parrott ; the Dahlgren 150-pounder; the Bureau 600-pounder, (42-inch bore;) the Mann breech-loader, 8-inch; the Erics- son 13-inch ; the Wiard 15-inch. 2. Of these the Parrott 150-pounder was adopted for the naval ser- vice, but was subsequently laid aside on the recommendation of a board. The proofs to which each has been subjected will be found in the replies to previous queries. The mode of proceeding in proof or experiment with these guns has not been such, owing to the pressure of circumstances, as to furnish the means of replying accurately in regard to the endurance of these rifled cannon. Some of the guns of different systems have exhibited endurance under fire that would satisfy any requirement of naval service; and others of the same kind have proved so inferior as to destroy confidence. It must be kept in view that a uniform endurance with service charges is the chief desideratum, even though it be moderate. This cannot be supplied by the excessive endurance of some pieces if others fall very low. To the last paragraph of this interrogatory, I would say, that this bureau is not cognizant of any rifled cannon of heavy calibre whose admitted character would warrant its being adopted for the ordnance of our navy. A glance at the accounts from abroad do not show that in this respect we are worse off than other naval powers. England has been credited more than once with being on the eve of solving the problem. But Armstrong and his coadjutors have passed off the stage to make place for others who in the end may prove as unlucky as himself. But a few days since we learnt that one of the present favorite guns gave way, prematurely, to the great detriment of the rep- utation of its class, as will be seen by the following extract from the Army and Navy Journal of the 23d of January, 1869 : Our London military contemporary informs us that the admiralty are alarmed at the explo- sion of a Fraser gun at Woolwich. It says they have been in communication with the war office, expressing their apprehensions on the subject of the large forgings in vogue at the royal gun factories, though they have not gone as far as to repudiate the Fraser gun alto- gether. Indeed, eight 10-inch guns have just been put on board the Hercules. ######* We can only regret (adds the Gazette) that the idea of a good gun seems as far off as ever, meaning by a ' good," one which can be relied on with perfect security. Of course we will some day have a rifle cannon equal to any require- ment, but much time may elapse and more money will be spent before that will happen. GUN-BLOCKS. At the commencement of the year 1868, a reply was forwarded to a call of the committee for information in regard to iron castings for rifle cannon that were to be finished at the Washington navy yard, which will not be fully understood without further explanation, and I therefore ask permission to supply this now very briefly. The whole of this operation is to be considered as part of an effort by the Bureau of Ordnance to meet the deficiencies of the navy in rifle can- EXPERIMENTS ON HEAVY ORDNANCE. 145 non, under circumstances too urgent to permit of the least delay. It cannot therefore be tried by any of the ordinary conditions of peaceable times. When the rebellion broke out, in April, 1861, by the attack on Fort Sumter, the navy was the least prepared to exert the power which the extreme need of the country demanded. Among other deficiencies it was without a single rifle cannon of heavy calibre. The Bureau of Ordnance had for several years previous retarded the investigation of this question, which I desired ; and, with the exception of some rifle howitzers, to complete the boat armament, and a few iron cannon for experiment, we had no rifle pieces for the naval service. In view of the great emergency, it became the imperative duty of the Bureau of Ordnance to resort to every expedient that held out the least prospect of meeting the immediate necessity, and reluctant as I might be to venture upon results with the scanty data at hand, particularly as the great difficulty of the problem had staggered the ablest ordnance men in other countries, yet I felt it incumbent on me to spare no effort that would contribute to the common good, even if in so doing some damage might be incurred to my professional reputation. All the foundries and workshops of the north were being filled rapidly with orders for the building of steam engines and the fabrication of can- non for the army and navy ; so that it became expedient to call into action the mechanical resources of the navy yard here, and in this way the castings intended for rifled cannon, which could not be then finished chiefly at the Pittsburg foundry, were brought to Washington for that purpose. It is not to be supposed that there was the same leisure for careful scrutiny when the rebel flag was flaunted in sight of the capital that there had been in the recent periods of peace. The founders proceeded to make the castings rapidly, and as fast as room occurred on the lathes of the navy yard, these were put under process. With all the haste that could be used, the first of these were not com- pleted until the latter end of the year 1861, when the examination of the iron and the test of firing were had. I then became aware that the tensile strength and density were by no means satisfactory, and drew the attention of the bureau to the proba- bility of accident if this was not rectified. A little later I was led to doubt if these castings were of cold-blast iron, and I recommended the chief of bureau to withdraw all of them from service that were not cold- blast, and to receive none that were warm-blast. I may here remark that some difference of opinion exists in regard to the necessity of cold-blast iron for cannon. It would consume too much of the time of the committee for me to state the questions in detail, but with a single exception I believe it may be said that experienced ord- nance officers have insisted on cold-blast iron, while the founders con- sider warm-blast good enough. It is certainly easier and cheaper, at first cost, to make iron by warm-blast in smelting. My own opinion, derived from no little experience in iron, always has been in favor of cold-blast, even for smooth-bores. As the examination proceeded, the lack in quality appeared in greater degree. In two 50-pounders the density fell as low as 7.121 and 7.160. In stating this to the bureau (26th April, 1862,) I remarked: It would be hazardous to send into service guns of such low density. All the difficulties which have been experienced with the 80-pounders and 150-pounders are entirely owing to this and to other disqualifying causes, and I have already asked that blocks affording a more suitable density might be sent here, but have not yet been furnished with them. Rep. No. 266 10 146 EXPERIMENTS ON HEAVY ORDNANCE. In this stage of the matter, the House of Bepresentatives asked for information, and was answered by myself July 8, 1862; and by Captain Harwood, the chief of bureau, July 10, 1862. From my own reply, I extract the following : The fabrication of rifled cannon may be said to have only begun in this yard with the present struggle for the Union. Little or nothing more was done between this and the period when Fort Sumter was attacked. Then the work of armament really began, and this department, so limited in its means, and so little calculated to render any great assistance in the fabrication of cannon, was called upon to contribute its quota, which has, I believe, been faithfully rendered. The work has been conducted day and night, even while the flag of rebellion was flying within sight, not omitting Sunday, for which I did not escape censure. To this the bureau added, July 10, 1862 : The investigations on the subject of rifle cannon had hardly commenced at the breaking out of the rebellion, &c., &c. See page under head of (" Rifle 150-/Hwnrfer.") The origin of the whole trouble lay entirely in the postponement of the question by former chiefs of bureau. In 1856 Captain Ingraham, then chief of bureau, would take no action on my proposition to make a heavy rifled cannon, nor in 1857, when I renewed it. In 1859 I was allowed to make some experiments on a small scale, but even this was arrested in January, 1860. Permission to continue was yielded in October, 1860, when rebellion stared us in the face. But it was too late; all the millions since spent by the country would not buy back the years that had gone by unim- proved, and we went into the conflict like a man picking up the first weapon at hand. The report of progress which I made in December, 1860, (already given,) should have been possible four years previously, w^hen one cast- ing after another, in due succession, would have afforded the means of correction economically, instead of the wholesale trials of 1861, when success was worth any cost, and which cannot therefore be tried by the standard of peaceable times, but only by the desperate necessities of the Union striving for existence. In view of which it became not the Bureau of Ordnance nor myself to hesitate because some personal sacrifice was demanded. In conclusion, the material then procured is by no means useless, even if it be unfit for rifled cannon ; the best of the castings may be made into smooth-bores, and the balance used for other purposes. CONCLUSION. The queries of the committee were received by me on the 25th Decem- ber, and it was my desire to reply to them in the fullest manner; the brief period that remained of the session would not permit me, however, to do more than is presented in the foregoing. I trust it will have the consideration of the committee that my direct connection with the Bureau of Ordnance ceased some five years ago, and was only resumed a few months since ; that I was absent from the United States during the greater part of this period, in command, successively, of two of our squadrons. My knowledge, therefore, of much of the matter that forms the subject of the committee's inquiry was unavoidably to be derived or renewed from a scrutiny of the records of this office accumu- lating since 1861, amounting (as reported to me) to more than 700 file- books of letters, correspondence, reports, inspections, &c. The committee may conceive that it was impossible for me to do this myself or to have it done with entire exactness in the time at niy dis- EXPERIMENTS ON HEAVY ORDNANCE. 147 posal. I hope, however, that the purposes of the committee may be suffi- ciently met by further explanation in any respect that the committee may indicate. With the permission of the committee, I beg leave to note in conclu- sion 1. That when the rebellion began in 1861, the experimental investiga- tion of the rifled cannon problem had gone no further than the rifled howitzer for boats, (entirely successful,) and some of lighter iron calibres the progress having been delayed previously (1856 and 1857) by the decision of the chief of the bureau. 2. As a consequence the navy was destitute of any system of heavy rifled cannon that was entitled to reliance when the rebellion broke out, and it became necessary to meet the incessant and general demand for these guns by supplying for immediate use whatever was procurable and offered the prospect of even temporary usefulness; and thus it was that the course of investigation which belonged to the experimental ground was unavoidably transferred to actual service, with the certainty of increased cost and at the risk of life; there was no help for it. It does not appear that any other course was open to the naval bureau. It was well, indeed, that under such trying circumstances the navy had a sure reli- ance on the most powerful smooth-bores then ~known. The results are before the committee; unsatisfactory, it is true, but not more so than those of foreign navies, attained in peaceable times, with every advantage of careful and costly experiment. The attention of the committee has already been drawn (reply to query 12) to the reported failure of one of the successors of the Armstrong system, which had swept away the long established ordnance of Eng- land, and was in its turn put aside as unreliable. This later favorite seemed to fulfil the promise of hopes long deferred, and now comes its probable condemnation. An armament of new breech-loading, heavy rifled cannon, which I recently saw on board one of the latest French iron-clads, has, I am told by a naval officer just returned from Europe, lately disappointed expec- tation by the bursting of one of the kind in a ship of the squadron of evolution. We have now the opportunity of guarding the future against a recur- rence of the losses and failures experienced in the late struggle by resort- ing to careful experiment, the most sure of success at the least cost. The difficulty of the question has been much ameliorated by the changes of views which have occurred in regard to the uses of rifled cannon since the opening of the rebellion. Then all opinion, professional or public, placed no dependence on cannon that were not rifled; the utmost anxiety was manifested to displace the smooth-bores and substitute rifled cannon. Had it been possible nothing else would have appeared in our ships, so extravagant were the expec- tations that prevailed of their power. Yery different are the views now entertained. The experience of battle in the use of both kinds of ordnance has restored the confidence in smooth- bores, not only for their certain and safe endurance, but for their power and their accuracy within any range that earnest men are likely to try issues on the ocean. It has been shown that the true role of rifled cannon afloat is very limited, and that its numbers on shipboard will therefore be proportionally few. I can offer no bette revidence in this respect than the views of Vice- 148 EXPERIMENTS ON HEAVY ORDNANCE. Admiral Porter, whose great experience in severe action will not fail to receive due weight. He says : The gun which I deem best adapted to the general use in the navy is the 11 -inch gun, which can be carried on board even our smallest vessels, worked in a sea-way if the vessels are properly constructed, and almost as rapidly as a 32-pounder ; at all events rapidly enough for all practical purposes. I consider its accuracy much greater than any rifle gun or any gun of a smaller calibre. That, I believe, has been tested to the satisfaction of most navy officers. 1 am no advocate for a large number of heavy rifled guns on board ship, although I think it does very well to have a few combined with smooth-bores. I have no confidence in their accuracy at sea ; on shore, where they are mounted on a good level platform, and where allowances can be made for wind and weather, they will do very well, but on shipboard, where there is the least motion, they fire very inaccurately. If they should strike the w?.ter before reaching the object they are deflected at an angle of 45 and go wide of the mark. That most important power, " ricochet firing," is entirely lost in the rifle guns, and in a sea-way a vessel armed with ] 1-inch guns is, in my opinion, a match for a vessel with twice the number of rifle guns. I am not prejudiced against rifle guns from the fact that I have had a good many of them burst, as I believe that most of those that burst were badly constructed, which I think is the case with all banded guns. I regret to say that I have seen many men killed and wounded by the bursting of 100- pounder rifles, and many vessels injured. The result of these accidents has been to impair the confidence of sailors in that class of guns, and were I going to sea I would not have one on board. I have never, to my knowledge, known an accident happen to the 9, 10, or 11-inch guns, three of the best guns we have ever had in our navy ; and in battle men stand behind these guns in perfect security, knowing that the chance of their bursting is very small. I do not want you to suppose that I am an advocate for the abolition of rifle guns, for I believe that excellent cannon of that kind can be made of cast-iron without banding. What we need is a course of well-conducted experiment, carefully, logically pursued by officers whose experience renders them cognizant of all views of the question. My report of 1862, as chief of bureau, shows that I then attained results which should have led the way to further experiment and per- haps to useful conclusions. It is to be regretted that these were not pursued to that end. The ample building at the navy yard, where I had hoped to examine fully into the quality of different American iron, the modes of treatment likely to insure the best metal, and to test the various models, has been converted into a receptacle for unused and obsolete ordnance stores of all kinds. I feel that the committee can restore the operations of this bureau to their true course, by recommending some moderate sum for experimental purposes, and by separating the practical ordnance duties from the merely administrative ; which is the more needed in the navy because we have no distinct ordnance corps like the army, but trust to details of officers from the line of service for carrying on every branch of naval ordnance duty, from the inspection of cannon to fitting of ships at the navy. yard. For the convenient reference of the committee I annex a list of the most recent chiefs of Ordnance Bureau : Captain Ingraham, March 10, 1856, to September, 23, 1860 ; Captain Magruder, September 24, 1860, to April 23, 1861 ; Captain Harwood, April 24, 1861, to July 22, 1862 ; Captain Dahlgren, July 22, 1862, to June 24, 1863 ; Captain Wise, June 27, 1863, to June 1, 1868; Rear- Admiral Dahlgren, July 22, 1868, to the present date. I have the honor to be, very respectfully, your obedient servant, J. S. DAHLGKEN, Rear-Admiral and Chief 'of Bureau. FEBRUARY 11, 1869. EXPERIMENTS ON HEAVY ORDNANCE. 149 APPENDIX C. OFFICIAL REPORTS. From the report of the Chief of Ordnance, Wavy Department, for 1861. With reference to rifled cannon, for which there has been an unceasing demand, the bureau, after mature consideration, decided that it would be injudicious to rifle the old navy models, on account of their form not being adapted to the severe strain to which rifled ordnance is subjected. Another consideration which added force to this decision was, that in the guns formerly made for the navy the treatment of the iron was dif- ferent from that pursued in more recent years, and which is now deemed to be a matter of paramount importance. But to meet as near as was practicable pressing emergencies, the bureau, after due investigation into the best description of this kind of ordnance, selected that which was available, and which has been pro- duced by the enterprise of private establishments. Meanwhile the genius of Commander Dahlgren designed new models for rifled cannon, which have been put in hand ; and now, with every possible appliance of foundries and machine shops that are found avail- able throughout the country, as well in the public works as in private establishments, there is every reason to believe that, under any probable contingency which may arise, the demand for ordnance will be promptly supplied with cannon fully equal, if not superior, to any known to exist at home or abroad. From the report of the Chief of Ordnance, Navy Department, for 1862. The constant and very natural solicitude manifested by the public in the changes which have been and continue to be made in the construc- tion and armament of our ships-of-war may warrant a more extended notice of technical detail than might otherwise find place in a document of this nature. And yet no definite conclusion has been reached in regard to either of these important problems. Indeed, the most casual observer of current events can hardly fail to perceive that neither of them has advanced beyond the first proposition. * # * * * * * The advantage of which is now apparent from the fact that our 9- inch and 11-inch guns are found to be, in a measure, available against iron-plating, because they will endure solid shot fired with one-half greater,. and even double, the original charges. So that we have the leisure to consider and devise any other species of ordnance that may be better adapted to the purpose, and are not pre- cipitated into hasty or questionable measures. ******* The ordnance expert can by no means rejoice in being free from diffi- culties that puzzle his ingenuity. The number of cannon being reduced to a third of the number he is accustomed to rely upon, how shall he supply the loss of force by the weight and kind of those which remain I If he acquires power by greater weight, he loses by loss of time in manipulation of gun and projectile ; hence some reduction by slowness of repetition. Then, again, shall he use our smooth-bore, breech or muzzle- loaders? Shall he pierce or crush and break bolts and strip off the armor, or shall he even attempt to enter the interior with shells ? 150 EXPERIMENTS ON HEAVY ORDNANCE. How economize the open space of the ports when the gun is out, or close it when in ? Leaving these queries to be answered by the parties most concerned, it will suffice here to say that, just now, the offence has decidedly the advantage, and no sea- going ship is considered to be so armored as to be impregnable to artillery. Of the French results and inferences touch- ing the several points we know nothing beyond what is necessarily dis- closed to the observer in the construction of ships. The British government have practiced less reticence ; and if we are not permitted to become acquainted with the reasoning of their officials, the results from which they do reason are so far public that one cannot err very widely as to their general bearing. A large number of witnesses have usually been present at the trials, including officers, engineers, ship-builders, and others, civil and official. The press is also well represented, and in a few days afterwards all the proceedings are detailed minutely to the public, discussed in Parliament, and in meetings where the ablest professional men are assembled for the purpose. So far as an opinion can be formed from such sources, one is led to conclude that those who, from their distinguished abilities and oppor- tunities of investigation, should be best qualified to judge, have arrived at no final decision in regard to any of the essential points of the prob- lem above stated, which is, indeed, reasonable, when it is noticed to what extent these differ and even conflict. About a year since (October 21, 1861) a number of eminent dignita- ries, military, naval, and civil, met, in order to witness the trial of a target representing the Warrior's sides. It was supposed that all the power which ordnance could exert for such a purpose was brought into play ; and after this had been done it seemed as if the witnesses were generally favorably impressed with the endurance of the target, and therefore of the Warrior. But not long after (April 8, 1862) Sir William Armstrong placed in front of this, or a similar target, a gun which he had just completed ; it threw a round shot of 156 pounds, which, with 50 pounds of powder, most unexpectedly changed the whole aspect of the question by its treat- ment of the target, which was said to have been completely pierced. The revulsion in common opinion went so far as to discredit the Warrior entirely, and the fallibility of that vessel was pronounced certain. But during a discussion in Parliament a member maintained that the facts had not been accurately stated even by official authority, and the deductions were consequently more unfavorable to the target than was correct. He even affirmed that the target had not been fatally injured, but would in fact have kept out the shot from entering a vessel. Whether for this reason or not, the trial was repeated, and very fully disposed of all doubts in favor of the target j but it settled the gun also, which burst at the fourth round. Thus demonstrating that if the target were penetrable by the fire of such a piece of ordnance, it was only by an effort that destroyed the gun also a risk not to be thought of on shipboard. And hence it was inferred that the Warrior was impregnable to the effort of any ordnance that could be then used safely against her. The triumph of the defence was, however, of short duration ; for the rupture of the Armstrong gun left the way open to other competitors, and a long-neglected piece that had lain remote from view for several years was suggested as deserving of an opportunity to try its powers. This was the Horsfall 13-inch, of wrought iron. Its first blow, with a EXPERIMENTS ON HEAVY ORDNANCE. 151 shot of 280 pounds, was decisive. The plate was pierced and badly injured, while the endurance of the gun was untouched. As if to complete the entire failure of the defence, and to puzzle its advocates, Mr. Whitworth undertook to drive a shell through a stout iron-plated target, which he accomplished. So that the system of armor that had been relied on was proven to be vulnerable by shells, as well as by shot, which was an unhoped-for advan- tage on the side of the attack. Here it will probably rest for the while, until the defence shall be able to devise some plan of greater efficacy. It would be unwise, however, to rush to the conclusion that armor is needless, because the most powerful ordnance should, under skilful guidance, be able to pierce it. For, even against such cannon, a ship may delay the final disaster long enough to make its own guns of avail ; and when opposed to any but these heaviest pieces, will still be in effect impregnable. The case of the Monitor and Merrimack affords an illustration. No one supposes that either of these vessels could have escaped serious injury if subjected to a course of target-firing from the most recent and powerful descriptions of ordnance, yet they sustained for four hours the utmost effort of each other's batteries. The Monitor was hardly more than scarred by the fire of the very guns Avhich, on the preceding day, had in a fourth of the time acted most destructively on the hulls and crews of two fine wooden frigates. A very high official authority (Duke of Somerset, First Lord of the Admiralty, House of Lords, April 3, 1862) has, to be sure, imputed the default of injury to life or limb in this combat to a lack of power in the artillery which the two vessels carried ; which is no doubt true ; but it is equally true that no guns of like weight and kind now used in the British navy would have effected as much under like circumstances. * ***** The operations that have been conducted here with reference to the power of different cannon and projectiles, as well as the resistance of iron plating, have been so far satisfactory that the results derived have been consistent. ******* There must be, however, a material reduction in the celerity of fire with guns and projectiles so large as the 15-inch, whatever may be the mechanical appliances which may be brought to assist. An 11-inch gun, with a well-disciplined crew, can be fired once a minute ; but there must be much improvement in any mode now sug- gested before a 15-inch gun can be fired once in thrice that time. As a certain capacity for repetition is essential to the general power of a battery, there is thus involved a disadvantage which can only be compensated to any extent by the great concentration of effect in the individual projectiles. For it may be conceived that the effects of shells of 330 pounds, and shot of 450 pounds, will be damaging beyond any experience in former battles. What may be the power of such ordnance against iron-cased ships comparative or absolute remains to be ascer- tained. This, as well as the piece itself, is yet but an experiment. ****** On another occasion an 11-inch gun was fired 500 times, of which 170 fires per day were made in two successive days, which so heated the gun that it was found to be warm 18 hours afterwards. No sign of weakness was detected. 152 EXPERIMENTS ON HEAVY ORDNANCE. From the report of the Chief of Ordnance, N~avy Department, for 1863. The only establishments in the country which were prepared for the work of founding heavy cannon, when the rebellion took place, were the South Boston, Fort Pitt, and West Point; the Tredegar Works at Eich- mond, Virginia, having passed into the hands of the rebels. No govern- ment establishment of the kind existed, and consequently the sole reli- ance of both army and navy, at the commencement of our difficulties, was upon these three foundries. Eight nobly, however, did they come to the rescue in the hour of need, and thus afforded time for the bureau to seek other manufacturers who might be willing to undertake the work of supplying the navy with cannon. Although such operations are always attended with great risk to those who were unaccustomed to the casting of heavy guns, it was not long before several other establishments were ready to co-operate, and the work of producing the guns of various calibres required was commenced, and, I am happy to say, been most successfully prosecuted. ****** In procuring cannon for the navy the same conditions have been exacted from all these foundries, as regards the character of metal and every other element necessary to constitute good and reliable guns. No gun has been accepted, as a standard, which has not been subjected to the ordeal of 1,000 rounds of service charges. With this standard thus established, all the guns of a contract must coincide in their com- posite elements. The only exception to this rule has been in the case of the 15-inch guns cast upon the plan of Major Eodman, of the United States army. Time did not permit of this proof being applied, and the guns were necessarily accepted and put into service, after having endured, how- ever, somewhat more than the tests prescribed by the army regulations. It is most gratifying to know that the judgment of the Navy Depart- ment has been sustained by the result of the further test which has been applied to the first gun of this class made for the navy, and which is still undergoing a series of experimental firing after being modified in form. All doubt is thus removed of the ability of the Fort Pitt foundry to pro- duce guns of this great size which can safely be relied upon ; and the power thereby added to the fire of our monitors has been most fully exemplified in the capture of the Atlanta. Before dismissing this branch of its report, it is just that the bureau should bear special testimony to the prompt and efficient manner in which the West Point foundry has also done its share in supplying the need of the service for a new style of ordnance. The introduction of a few rifled guns of heavy calibre into the bat- teries of ships had already taken place in foreign navies prior to the date of our present rebellion ; and in our own service experiments were being conducted at the Washington navy yard, under the direction of Eear- Admiral Dahlgren, for the purpose of devising a system of rifled ordnance. Nothing decisive, however, has been accomplished, except with the rifled howitzer, and the experiments were rudely interrupted in the spring of 1861. At the same time Mr. Parrott was engaged in perfecting his present system, and the results obtained by him were so satisfactory that in the summer of 1862 the bureau, in conjunction with the army ordnance, directed a 100-pounder to be subjected to a series of 1,000 service rounds. The gun stood the test without bursting, and its accuracy and range EXPERIMENTS ON HEAVY ORDNANCE. 153 were considered sufficiently good to warrant the adoption of these rifled guns as a permanent part of our naval armament. Since then the demand for the several calibres has been unceasing ; and, as before stated, they are to be found on board nearly every vessel now in service, and will continue to be supplied until some better system is established. Finally, from personal inspection, and witnessing the firing of over 100 rounds from these guns at the West Point foundry recently, the bureau is satisfied that whenever attention is paid to details and even moderate skill in the manner of loading and firing is attained, they will prove the most serviceable rifled guns that have ever been introduced into any service. From the report of the Chief of Ordnance, War Department, for 1864. The heavy gun of 20-inch calibre, for sea-coast fortifications, has been successfully cast and finished, and a suitable carriage to mount it has been prepared. It is now ready for experimental trials at Fort Hamil- ton, in New York harbor, and the proper targets and other preparations for testing its efficiency against the strongest war vessels, and ascertain- ing the best manner of handling it in service, have been ordered to be made. The results of these trials will demonstrate whether the expecta- tions which theory warrants, of the destructive effects of this gun and its value for defensive works covering narrow passes, are realized, and whether such guns should be multiplied ; and if so, to what extent. If they should establish the affirmative of this question, the cost of these trials will be far outweighed by the advantages obtained from them ; if otherwise, the loss will be insignificant in itself, and will probably be a gain eventually, by preventing future experiments in the same line, and settling the question of the largest effective calibre for sea-coast cannon. From the report of the Chief of Ordnance of the Navy Department for 1864. COMPOSITION OF BATTERIES. The governing rule in arming our ships of war has been to place on board of them the very heaviest and most effective gun they can bear with safety. In general it may be stated, that the 9-inch are used for broadside; the 10-inch, 11-inch, and the Parrott rifles in pivot ; the 15-inch for the mon- itor turrets, and the bronze howitzers and rifles for boat and deck service in shore. A few of our ships continue to be armed with the 32-pounder and 8-inch guns of the old system 5 but these will probably give way to the modified guns of similar classes above alluded to. As no special changes have been made in the general arrangement of batteries since my last report, the same vessels, mentioned therein as types of their rates, may be again taken to illustrate the system of arma- ment still in vogue. Thus the battery of a first-rate is represented by the Minnesota carrying One 150-pounder rifled, ) . . , . One 11-inch smooth, } m plvot > Forty-two 9-inch smooth, ) . broadside Four 100-pounders, rifled, } u le > and four howitzers. 154 EXPERIMENTS ON HEAVY ORDNANCE. Of a second-rate by the Brooklyn, carrying Two 100-pounder rifled, in pivot; Twenty 9-ineh smooth, ) . , /! Two 60-pounder rifledj } ln broadside ' and two howitzers. Of a third-rate by the Eutaw, carrying Two 100-pounder rifled, in pivot ; Four 9-iuch smooth, } Two 24-pounders, smooth, > in broadside. Two 20-pounders, rifled, ) Of the fourth-rate by the Owasco, carrying One 11-inch smooth, ) . . , One 20-pounder rifled, f u Two 24-pounders, howitzers, in broadside. And by the Nipsic, carrying One 150-pounder rifle, ) . One 30-pounder rifle, } m pivot 5 Two 9-inch smooth, in broadside, and four howitzers. Of the monitors, by The Tonawanda, four 15-inch; The Onondaga, two 15-inch and two 150-pounders ; And Montauk, one 15-inch and one 1 50-pounder. Of the iron-plated gunboat of the western rivers, by the Carondelet, carrying three 9-inch, four 8-inch, two 100-pounder rifles, one 50-pounder rifle, one 30-pounder rifle. The development of the power of each individual ship named as repre- sentatives of the several rates is In shot. In shells. First rate 2,606 Ibs. 2,123 Ibs. Second rate 1,220 990 Third rate 424 343 Fourth rate 210 183 And 294 255 In the monitors Tonawanda 1,704 1,320 Onondaga 1,180 930 Montauk 606 465 In the western gunboat Carondelet 588 - 480 It will be noticed that in each of the four rates of vessels above men- tioned pivot guns are associated with those of broadside, so as to meet more fully the necessity for long range at high elevations in chasing or bombardment, and at the same time to maintain a direct fire without materially altering the course of the vessel. The mechanical arrange- ment of the pivot carriage also enables the mounting and working with ease a much heavier gun than could possibly be handled on an ordinary broadside carriage. These pivot guns are always placed near the ends of the vessel, and therefore do not interfere in the least with the working of the broadside. The rapidity of fire from them is, of course, not so great as from an indi- vidual gun of broadside, but is fully sufficient for the purpose of accuracy at ranges beyond the reach of the lesser calibres. No ship can, there- fore, be considered properly armed that has not a pivot gun of greater EXPERIMENTS ON HEAVY ORDNANCE. 155 power and range than the guns of broadside. But whether a battery, consisting entirely of heavy pivot guns, would be more formidable than one of broadside alone the aggregate weights being equal has not yet been tried, the only effort of the kind being that of the Niagara, which has a battery of twelve 150-pounder rifles mounted in pivot, and no regu- lar broadside guns. THE FOUNDRIES. The number of these establishments engaged in the fabrication of can- non for the navy has been reduced by one since the date of my last report, the Portland Company having withdrawn from their contract. The others have been fully employed in the work of keeping the navy sup- plied with guns of unequalled strength and beauty of finish, from the ponderous 15-inch to the light 32-pounder. No delay or embarrassment has occurred in the delivery of the cannon contracted for, and the bureau is more than ever assured of the reliability of the firms engaged in this important business. The Fort Pitt foundry, with its immense facilities and very great expe- rience in the art of founding cannon, was at first the only establishment able and willing to undertake the task of making the 15-inch guns. But during the past year two other foundries the South Boston and the Scott foundries, at Beading, Pennsylvania, having completed all the arrangements necessary for the process of hollow casting have now each a contract for this class of gun. No difficulty whatever is antici- pated in the fabrication of these very large cannon, for the irons now used by the respective foundries are known to be of the very best quality for the purpose. The primary and most important element being thus assured, the remainder of the task is entirely within the mechanical ability of the foundries. It is, therefore, no idle boast, that the cannon of the United States navy, made exclusively from American irons, are unsurpassed by those of any other nation ; and this will continue to be the case so long as the enterprise of our citizens is left untrammelled, and full opportunities are afforded for the exercise of their skill in this most important art. Besides the 15-inch guns, the Fort Pitt, South Boston, and Reading foundries are all engaged in making the other classes in use, including also the new models of 8-inch and 32-pounders elsewhere alluded to. The Builders' Iron Foundry, at Providence, Ehode Island, has just completed a contract for 11-inch guns, and is now engaged on a new one for the 8-inch and 32-pounders; while the firm of Hinkley, Williams & Co. are still engaged upon their contract for 11-inch guns. Thus the work has been steadily prosecuted during the past year, and will be continued by these foundries as fast as the demand for the smooth-bores increases. The cast-iron banded rifles of Mr. Parrott, made at the West Point foundry, are still the only kind used in the navy, except the bronze 12 and 20-pounders of Bear- Admiral Dahlgren. Since November of last year there have been added to the stock of these rifles on hand at the depots and in service 385 of the different calibres, including 20 new 60- pounders, making a total at present available of 1,005 guns, after deduct- ing 23 lost or disabled by the accidents of battle. Of these thus lost or disabled, six gave way at the breech, four were broken by the explosion of shells near the muzzle, three were cracked in the bodies, two were condemned for excessive enlargement of vent, seven were lost by wreck, and three captured by the rebels. The percentage of loss by rupture and enlargement is therefore very small. It may be remarked that no rifled gun has yet been devised which can 156 EXPERIMENTS ON HEAVY OEDNANCE. be considered perfect, and the bureau has sought in vain among the sys- tems of European nations and the improvements of our own country for a better gun, taken as a whole, than the Parrott rifle. Its lifetime, as fixed by the inventor, is 750 rounds, but the navy guns have in many instances shown a greater endurance. It is true that reports are occasionally received of failures with the Parrott projectiles, (also prepared at the West Point foundry,) but these are again counterbalanced by the most favorable reports ; and it is cer- tain that, whenever a close attention is paid to details in loading and firing, these guns may be relied upon for range and accuracy. But if these details from any cause are not sufficiently attended to, the firing of no rifled gun can be considered safe or certain. At all events, what- ever may be the defects of the Parrott system of rifled ordnance, no other has yet been produced which commends itself so strongly to the service ; and until another and a better one is devised and subjected to the same ordeal, the bureau will continue to place its guns in the batteries of ships as important auxiliaries to the smooth-bore pivots. The condition of endurance is undoubtedly the first to be secured in all guns, and no one expects to find this in as great a degree in the rifle as in the smooth-bore. Hence the cast-iron gun of Mr. Parrott, although strengthened by a spiral coil of wrought-iron around the locality of great- est strain, is by no means to be expected to last as long under protracted firing as a smooth-bore of the same calibre. But its probable strength when carefully used, as all ordnance should be, is sufficiently ascertained to avoid accidental rupture by attempting too much. Propositions have been made to supersede cast-iron for rifles (and in fact for smooth-bores also) by wrought-iron ; and a heavy wrought-irou rifled gun of 7-inch bore, forged in a peculiar manner, is even now under process of trial, as well as one of smooth-bore, designed and constructed by our distinguished citizen, Mr. John Ericsson. But the experiments have not been sufficiently advanced with either of these guns to form a reliable judgment as to the probable result, for there are many grave questions involved besides the ability to resist rupture, and these will inevitably be developed under the strain of excessive charges. For a long time the question of casting guns in a solid mass, and cool- ing them from the exterior, or casting them hollow, and cooling from the interior, upon the comprehensive plan of Major Eodman, has occupied the attention of the bureau ; and in a paper presented to the department on the subject, under date of May 17, 1864, an opinion was expressed decidedly in favor of the latter for all the heavy guns of the navy. As these views were subsequently fully sustained by the recorded opinions of the best authorities of the army and navy, and of the founders to whom the question was submitted, the official sanction of the depart- ment is only needed to enable the bureau to adopt this plan of founding in future all the cannon for the navy above an 8-inch calibre, after it shall have been submitted to Admiral Dahlgren. It may be remarked, that Mr. Parrott has recently determined to manufacture his heavy rifles in this way, being convinced that he thereby obtains a more solid gun, of greater uniform strength, and a surface of bore better suited to resist the action of the rifled projectiles. It would no doubt be interesting to describe fully the process of found- ing cannon by both methods ; but the limits of a general official report on various other subjects render this inexpedient. It is sufficient to know, however, that they are each perfectly understood by the men engaged in the business ; and since the casting of the enormous 20-inch cannon at Fort Pitt foundry for the army and navy, there really would seem to be EXPERIMENTS ON HEAVY ORDNANCE. 157 no limit to the ambition and daring of OUT artisans. These huge masses of iron were cast without the slightest difficulty, the time elapsing from the moment of tapping the furnaces to the complete tilling of the monld of the army gun being only 22 minutes. To produce this casting no less than 105 tons of iron were melted. This huge cannon having been bored and finished and the test speci- mens confirming the opinion formed of the soundness of the metal in working under the tools, it has been recently placed in battery at Fort Hamilton, where it will be subjected to proof at an early day. From the report of the Chief of Ordnance, War Department, for 1865. The importance to the country of having the armaments placed in the forts as rapidly as they can be prepared to receive them is so evident, that I have caused the manufacture of sea-coast gun-carriages to be con- tinued as rapidly as practicable at the two arsenals which possess the proper facilities for making them ; and orders have been given to the several founders, who have been engaged in making heavy guns for this department, for as many guns as carriages can be made for. I have been informed by the Chief Engineer that he will be prepared to receive guns in the forts faster than carriages can now be made, and it is in contemplation to increase the capacity for manufacturing sea-coast carriages. Experimental wrought-iron field and siege gun-carriages have also been made and tested, with results so satisfactory as to render it certain that these carriages may be advantageously substituted for the wooden carriages, and it is proposed to make no more gun-carriages of wood. The smooth-bore cannon of large calibre which have been used during the war have given satisfaction, and are regarded as perfectly reliable. The great importance of having reliable rifled guns of large calibre is universally admitted, and the attention of this government, and of the nations of Europe, has been directed to that object ; but so far, it is believed, without entire success in its accomplishment. The many failures, by bursting, of the celebrated Parrott guns in the land and naval service have weakened confidence in them, and make it the imperative duty of this department to seek elsewhere for a more reli- able rifle gun. Mr. Horatio Ames, of Falls Village, Connecticut, invented a plan of making wrought-iron guns, which many believe would possess those qualities which are so very desirable for guns of heavy calibre, and although the cost of these guns was necessarily very great in comparison with the cost of cast-iron guns, a conditional order was given to Mr. Ames to manufacture 15 of them for the government, the condition being that the guns should be superior to any rifled guns in the service. One of these guns was fired under the direction of a board of officers, who unanimously expressed the opinion that the "Ames wrought-iron guns possess, to a degree never before equalled by any cannon of equal weight offered to our service, the essential qualities of great lateral and longitudinal strength, and great powers of endurance under heavy charges ; that they are not liable to burst explosively and without warn- ing, even when fired under very high charges ; and that they are well adapted to the wants of the service generally, but especially whenever long ranges and high velocities are required." The board also expressed the opinion that the 15 Ames 7 -inch guns possessed sufficient weight and strength to receive an 8-inch bore, and recommended that the gun which had been fired under their direction should be reamed up to eight inches and subjected to further trial. 158 EXPERIMENTS ON HEAVY ORDNANCE. They further decidecUthat Mr. Ames had fulfilled the obligation incur- red by him in his contract to furnish the gun, and that so many of the guns as should endure a proof of 10 rounds with the service charge, and pass the proper inspection, should be accepted and paid for. Two of the 14 guns burst in proof, exhibiting serious defects in their manufacture defects in welding which I had been apprehensive could not be avoided. The guns which endured the proof of 10 rounds were accepted and paid for by this department. The gun which was fired under the direction of the board was bored up to eight inches and fired 24 times with service charges, when it burst. ###*##*# Believing that, with our present knowledge of the properties pf metals and our skill in working them, reliable rifle guns of large calibre can be made of cast iron, I have, with your sanction, caused a pair of 8-inch rifle guns of the supposed proper model and weight to be made. These guns are now at Fort Monroe undergoing extreme proof, and should their endurance be satisfactory it is proposed to have other guns like them made. From the report of tlie Chief of Ordnance, Navy Department, 1865. THE FOUNDRIES. The presumption is that the number of serviceable cannon which will be found by survey, together with those now being received from the contractors, will be amply sufficient to meet the wants of the navy for several years, and therefore the bureau does not contemplate entering into any new contracts for guns. The experience of the war has demon- strated that we can rely upon the private enterprise of our citizens to produce good cannon, and as rapidly as they are wanted. Therefore no apprehension need be entertained of any difficulty arising from the suspension of this work for the navy, and the return of these large work- shops to producing machinery and tools for commerce and the arts ; on the contrary, they will be better prepared with their acquired knowledge to enter at once upon the work, and to manufacture either such guns as are now in use, or upon any other models which future experiments may prove to be better adapted for naval use. I of course have now especial reference to cast-iron cannon, both smooth-bored and rifled, and to the manufacture of bronze howitzers ; for the art of fabricating wrought-iroii or steel cannon is yet in its infancy here, and remains an unsettled ques- tion abroad, only to be solved by a well-conducted series of careful experi- ments. So far, the results obtained by private enterprise in this country are very doubtful, and by no means to be relied upon. In fact, the difficul- ties of the problem are very much increased by the persistent efforts of inventors to produce wrought-iron or steel rifled ordnance of large calibre, instead of confining the preliminary trials to smooth-bore guns of the ordinary size. It should be remembered also that the advantages claimed for rifled cannon over smooth-bores are in many respects visionary, and do not bear the test of actual conflict, much less the more elaborate and quietly pursued experiments of the practice ground j and that whatever of extra- ordinary power or range may be obtained with them, is generally quali- fied in a great degree by the danger of premature rupture, under the strain of excessive charges and heavy projectiles necessary to produce such effects, and this whether the rifles are made of cast iron, wrought iron, or steel. EXPERIMENTS ON HEAVY ORDNANCE. 159 During the recent rebellion the cast-iron smooth-bore guns of the navy endured all of the severe service to which they were subjected, and proved their excellence everywhere and under all the conditions of actual war. Not a single gun of the Dahlgren system has burst "prematurely; and none of the 15-inch guns, even when fired with their heaviest charges, have ever failed except in the case of two or three which had their muzzles ruptured by the premature explosions of shells, the body of the gun even then remaining uninjured. For the ordinary warfare of wooden ships against each other, or against forts, these smooth-bore guns are undoubt- edly the best of their kind; while the practice at the test battery against armor plating shows that even the 11 -inch at close quarters is capable of piercing any thickness of iron or steel with which the sides of an ordi- nary cruiser intended to keep the seas could be covered with safety, and this without any danger of rupture from the use of increased charges, unless the gun has been very much weakened by previous service. The cast-iron rifled ordnance, manufactured by Mr. Parrott, of the West Point foundry, for the navy, did also good service within their sphere, and justly merited all the confidence placed in them, until it was rudely shaken by the disastrous rupture of several 100 and 150-pounders during the naval bombardment of Fort Fisher. Prompt measures were immediately taken to ascertain, if possible, the cause of these failures, and a board of ordnance officers, convened by order of the bureau, investigated the subject in all its bearings. Their final report is hereto appended. . Without waiting, however, for the decision of this board, the bureau directed the removal of the 150-pounders from service entirely, and re- duced the charge of the 100-pounders to 8 pounds of powder and a shell of 80 pounds. This reduction, and the gun confined to the work for which it was intended, and not used for every occasion, especially where the smooth-bores are more available, will,, it is believed, prevent the occurrence of premature rupture in future, provided, however, that the express and oft-repeated injunctions in relation to the use of rifled guns are strictly observed. The settled policy of the bureau is, at present, to arm our vessels with a mixed battery of pivot and broadside smooth-bore guns, governed with reference to calibre by the capacity and deck accommodation of individ- ual ships. The rifled guns are exceptional, and are intended simply as chase guns where long range is required, or to be used at great distances in repelling the attack of smaller and swifter opponents armed with similar pieces. The idea of a broadside armament composed exclusively of rifled guns is by no means warranted by the experience of the past war, and with the gathered strength and prestige of our navy we can aiford to await the results of the trials now going on in England and elsewhere, to bring forward a rifled gun of large calibre which can be trusted and used as a substitute for the smooth-bores in broadside or pivot.* Time, and a pro- digious expenditure, with corresponding successful results, are needed to satisfy ordnance men that the progress of science in the fabrication of "built-up" guns, whether composed wholly of wrought-iron, or of steel and wrought-iron combined, can produce either a rifled or smooth-bored cannon which will take the place of our present comparatively inexpen- sive cast-iron ordnance so far as endurance even is concerned. And when this, the first essential, is determined conclusively, there remain the other important questions between the smooth-bore and rifle of accu- * Breech-loading cannon made of steel, by Krupp, are now being tried in Prussia and Russia, but they find no favor in England. 160 EXPERIMENTS ON HEAVY ORDNANCE. racy at all available ranges, penetration, shock, and the certainty of ricochet fire. And in illustration of the advantage of this latter condi- tion of licochet fire, as being peculiarly the property of smooth-bore, I may refer to the published report of the army operations against Charles- ton, in which the commanding general bears testimony to the magnificent practice made by the iron-clad frigate New Ironsides with her 11-iuch guns against Fort Wagner. He says, in speaking of the final operations against that work: a Thirteen of our heavy Parrott rifles, 100, 200, and 300-pounders, pounded away at short though regular intervals at the southwest angle of the boomb-proof, while, during the day-time, the New Ironsides, with remarkable regularity and precision, kept an almost incessant stream of 11-inch shells from her eight-gun broadside ricochet- ing over the water against the sloping parapet of Wagner, whence, de- flected upwards with a low remaining velocity, they dropped vertically, exploding within or over the work, and rigorously searching every part of it except the subterranean shelters." A ricochet fire of this kind is simply impossible from rifled guns with elongated projectiles, whatever may be said of their superior powers of penetration. But the first essential of endurance in these " built-up" guns is by no means an accomplished fact, and in the development of any great power which they ought to possess by using heavy charges, they have hitherto developed also an inherent weakness which the greatest care in the pre- paration and fabrication of the materials of which they are composed is unable to overcome. A single gun may now and then be made which will show remarkable endurance under protracted firing; but a second or third, fabricated apparently like the first, yields prematurely, and dis- appoints the inventor when he least expects it With cast-iron ordnance, however, uniformity of endurance can be obtained even with rifles, as is exemplified by the trials of the three 100 pounders by the board on rifled ordnance, at Cold Spring, New York. We may, therefore, content ourselves with the possession, at least, of a system of smooth-bore and rifled ordnance which has stood the test of no ordinary conflict; and that we have every reason to expect that ample leisure will be afforded us in the future for the examination and trial of any new theories which may be presented for investigation. For this state of things we are mainly indebted to the enterprise of our citizens who own and have so ably conducted the cannon foundries of the north. From tlie Report of the Chief of Ordnance, War Department, for 1866. The experiments which have been carried on at Fort Monroe arsenal to test the power and endurance of the 8-inch and 12-inch rifle guns, made of cast iron, by this department, are highly satisfactory, and war- rant the belief that cast-iron rifle guns, of these calibres, may be intro- duced into the military service with safety and advantage. The 12-inch rifle, throwing a projectile of 600 pounds, and with 55 pounds of powder, has been fired 390 times. It is believed that no rifle gun of this calibre has ever given so great endurance. The further trial of these guns will be continued. #*#**## The armament of our fortifications now includes 3,546 serviceable cannon, of which 1,334 are of heavy calibres, (20, 15, 10 and 8-inch bores) and 653 are rifled cannon. EXPERIMENTS ON HEAVY ORDNANCE. 161 From the Report of the Chief of Ordnance, Navy Department, for 1866. The founding of cannon by either of the methods of solid or hollow casting has been fully tried in this country, and the results have been highly satisfactory. Nothing has yet transpired abroad in the efforts which have been made to produce better guns than ours, of steel alone, or built up of steel and wrought iron, to induce the fear that cast-iron ordnance will be surpassed in any essential of endurance, either as smooth-bores or rifles. As a notable instance in this connection, it may be stated that an army cast-iron Eodman 12-inch rifle has been fired at Fortress Monroe nearly 400 times, with charges of powder varying from 45 to 55 pounds, and shot weighing from 450 to 620 pounds. The gun still endures this service without yielding. The bureau therefore hesi- tates to recommend any expenditure in trials with built-up guns. From the Report of the Chief of Ordnance, War Department, for 1867. I stated in my last annual report that the work of arming the perma- nent fortifications, and of increasing their efficiency by providing guns of large calibre and replacing the perishable wooden carriages by dura- ble wrought-iron carriages, had progressed rapidly, and would be con- tinued as fast as the available means would admit until all the light guns, which are ineffective against iron-clad vessels, and all wooden car- riages, should have been superseded by the most durable and effective articles of their respective kinds. I am decidedly of opinion that this should be done, and that proper armaments should be provided and placed in the permanent forts as fast as they are prepared to receive them. Heavy guns and gun-carriages cannot be provided and mounted in the forts in a few days or in a few weeks, and if this government should become suddenly involved in war with a maritime power, or if war should be imminent, the country would not be satisfied if the important forts were unprovided with their proper armaments, and would demand the reason why they have not been provided, when Congress had furn- ished the necessary means, and it would hold the War Department responsible for the failure. Entertaining these views, I have felt it to be my imperative duty to provide guns and gun-carriages for the permanent forts as rapidly as the engineer department was prepared to have them mounted, and as the means provided by Congress would admit. On the 30th of June, 1866, the armaments of the forts included 3,546 serviceable cannon, of which 1,334 were of heavy calibre, (20, 15, 10. and 8 inches,) and 6^3 rifled, a majority of the guns being of smaller calibre than eight inches. It is known that smooth-bore guns of less calibre than eight inches are entirely ineffective against iron-clad war vessels, and should not constitute a part of the armament of any of our important forts. In December, 1866, this bureau was informed by the engineer depart- ment that 2,152 guns of heavy calibre (20, 15, and 13-inch smooth-bores and 10 and 12-inch rifles) would be required during the year 1867, or as soon as they could be furnished. As some of the guns which were asked for were of calibres and kinds which had not been adopted for our ser- vice, I requested that a board of officers might be instituted to deter- mine the calibres, the number of each calibre, and the proportion of rifle guns to smooth-bores, required to arm the permanent forts. The board, which was composed of engineer, ordnance, and artillery Eep. No. 266 11 162 EXPERIMENTS ON HEAVY ORDNANCE. officers, were unanimously of the opinion that u there would probably be required for the permanent fortifications, in addition to the ordnance now on hand, 805 smooth-bore guns of 20, 15, and 13 inches calibre, 810 rifles of 12 and 10 inches calibre, and 300 mortars of 15 and 13 inches calibre, to be provided from time to time, as the readiness of the forts to receive armament, the capacity of the foundries for its manufacture, and the appropriations applicable to its procurement, may warrant." This recommendation received the approval of the Secretary of War ad interim. None of these guns have yet been provided, and there are no existing orders or contracts for heavy cannon. Some of the forts are ready to receive guns of 13 inches calibre, and none have yet been provided. It is worthy of consideration whether some should not be provided at once and placed in the forts which are ready to receive them. This department recognizes the great importance of providing the very best and most reliable heavy guns for arming the forts, and has used all means within its control to obtain them. The founders have not been allowed to use any but the best gun iron known to the department, and it has been required that the metal in every gun shall fulfil certain established conditions with respect to ten- sile strength, density, and initial strain. A large number of guns have been condemned before reception because the metal did not fulfil all of the prescribed conditions. These requirements have produced excellent results. Persistent efforts have been made for some time past by ignorant or designing persons to destroy public confidence in the heavy guns which have been provided by the ordnance departments of the army and navy. Iron castings, placarded as representing the condition of the metal in our heavy guns, have been placed in conspicuous public places, and publications have appeared from time to time in prominent journals asserting that these guns were worthless; that they could only be fired with very light charges of powder, and that they would burst if fired a few times rapidly. These attempts to injure the character of our heavy ordnance undoubt- edly produced some effect on the public, and increased the responsibili- ties of this bureau. From the report of the Chief of Ordnance, Navy Department, for 1867. Since the date of my last annual report, all existing contracts for naval cannon have been completed and the guns delivered. With the exception of the 15-inch guns, it is believed that the stock on hand will meet the existing wants of the service. There is also a superabundant supply of serviceable projectiles of all kinds, together with a sufficiency of gunpowder, to meet the current demands of our cruisers. Kecent trials in England of a 15-inch gun of navy pattern, cast on Rodman's method, have fully vindicated the wisdom of the measure of introducing this calibre of cast-iron ordnance into our service. From the report of the Chief of Ordnance, War Department, for 1868. In the last annual report from this office the unanimous opinion of the board on the armament of fortifications, composed of engineer, ordnance, and artillery officers, was quoted, showing the necessity of a large num- ber of smooth-bore and rifle cannon for such armament. In pursuance of this opinion, approved by the War Department, and EXPERIMENTS ON HEAVY ORDNANCE. 163 at the request of the Chief of Engineers, a few of these cannon have been ordered, and are now nearly finished and ready for trial to test their power and endurance. It will be necessary to have a considerable num- ber of cannon manufactured of the kinds and calibre suitable for arming permanent fortifications, and proportionate to the numbers they are now in need of to make them effective against the most formidable attacks. As the preparation and completion of such armaments require much time, it is strongly recommended that the manufacture of the smooth- bore cannon, whose power and endurance are well established, be car- ried on, and that of the rifle cannon also, as soon as the results of the practical tests will authorize it, as fast as the means applicable thereto will admif. My attention having been called by the Chief of Engineers to an error in my annual report of last year, in which I say, " In December, 1866, this bureau was informed by the engineer department that 2,152 guns of heavy calibre (20, 15, and 13 -inch smooth-bores, and 10 and 12 -inch rifles) would be required during the year 1867, or as soon as they can be furnished." I take occasion to say that the letter of the Chief of Engi- neers of December 13, 1866, which was before me when the paragraph in my report was written, and from whictt the number was intended to be taken, called for 2,202, and that a subsequent letter from the Chief of Engineers, dated January 25, 1867, modified and reduced the number of guns called for from 2,202 to 1,915, agreeing with the number recom- mended by the armament board, as stated by me in my annual report for 1867, and approved by the War Department. The letter of the Chief of Engineers of January 25, 1867, was accidentally overlooked by me, and hence the error in my report as to the number of guns required by the engineer department, and which I beg leave to correct. I believed that our heavy cast-iron guns were the cheapest and most effective guns that were possessed by any nation, and experiments made to test their power and endurance have shown that it is so. The 20-inch gun has been fired with a charge of 200 pounds of powder and a shot weighing 1,100 pounds, and I have no hesitation in saying that this may be the regular charge for this gun. The range at 25 degrees elevation was more than 4 miles. A 15-inch gun has been fired as follows, viz : 7 times with 40 pounds of powder and a shell weighing 350 pounds, 5 times with 50 pounds of powder and a shell weighing 350 pounds. 70 times with 50 pounds of powder and a shot weighing 434 pounds. 59 times with 55 pounds of powder and a shot weighing 435 pounds. 1 time with 60 pounds of powder and a shot weighing 434 pounds. 1 time with 75 pounds of powder and a shot weighing 434 pounds. 1 time with 80 pounds of powder and a shot weighing 434 pounds. 1 time with 90 pounds of powder and a shot weighing 434 pounds. 125 times with 100 pounds of powder and a shot weighing 434 pounds. The mean range obtained with 100 pounds of powder and an elevation of 32 degrees was 7,732 yards. The mean initial velocity of the shot with the same charge was 1,510 feet per second. The rounds were fired in 35 minutes, which was as rapidly as the gun could be fired with 100 pounds of powder and a solid shot. There is no enlargement of the bore from firing and the metal has not been cut away by the powder. The gun appears to be perfectly serviceable in every respect. A 15-inch navy gun has been fired 12 times in 16 minutes with 40 and 55 pounds of powder and solid shot, without injury. 164 EXPERIMENTS ON HEAVY ORDNANCE. A number of 15-inch navy guns were fired in action several hundred times, and some of them with 60 pounds of powder and solid shot. The muzzles of two of them were blown off in consequence of the premature explosion of shells in the bores. No other injury was sustained by any of the guns. A 10-inch gun, the metal of which had a greater strain than the maxi- mum limit which had been established, was fired as follows, and without injury to the gun, viz : 18 times with 18 pounds of powder and a shot weighing 127 pounds. 17 times with 20 pounds of powder and a shot weighing 127 pounds. 2 times with 22 pounds of powder and a shot weighing 127 pounds. 453 times with 25 pounds of powder and a shot weighing 127 pounds. 120 times with 26 pounds of powder and a shot weighing 127 pounds. 4 times with 27 pounds of powder and a shot weighing 127 pounds. 1 time with 30 pounds of powder and a shot weighing 127 pounds. Only one 12-inch rifle gun has been made for this department. It has been fired as follows, and appears to be entirely serviceable, viz : 107 times with charges of powder varying between 35 and 85 pounds and a shell weighing 477 pounds. t 341 times with charges of powder varying between 35 and 80 pounds and a solid shot weighing 620 pounds. With 50 pounds of powder the mean initial velocity of 75 shot was 1,139 feet per second. These guns were cast hollow and cooled from the interior. Their cost is less than one-seventh that of steel or wrought-iron guns per pound, and they are believed to be more uniform in the quality of the metal and more reliable than either steel or wrought-iron guns. No other heavy guns have endured such proof or performed so much work as these guns have done, and it is confidently claimed that they are the cheapest, most reliable, and most effective heavy guns that have yet been produced. It is known that several foreign powers have pur- chased some of the 15-inch smooth-bores and 12-inch rifles in this country, and that at least two nations of Europe are manufacturing 15-inch cast- iron guns upon the plan which has been adopted by this department. While the results of actual trial have satisfactorily demonstrated the strength, efficiency, and reliability of our smooth-bore cast-iron cannon of large calibres, and similar trials have warranted the same expectations in regard to rifled cannon of cast iron, these latter have not as yet been tested to a sufficient extent to authorize their adoption for the service in preference to heavy rifled cannon of any other material. I should not, therefore, feel justified in procuring any large number of these rifled cannon at present, but would prefer to make further trials with such number only of them as may be necessary for that purpose, and to await the results before proceeding to procure the cannon of this kind which our permanent fortifications will require. So important is it, in my opinion, that these trials should be made, that I earnestly recommend that two 10-inch and two 12-inch rifle guns be made at once and fired to extremity, to test their power and endurance. From the report of the Chief of Ordnance, Navy Department, for 1868. Opinions differ quite as widely in regard to the preferable mode of developing ordnance power; whether it shall be by smooth or rifled bores by loading at breech or muzzle made from iron cast, or wrought, or 'from steel solid or in connected parts; the relation of mass to velo- city is also unsettled. In fact, the question involves the necessity of EXPERIMENTS ON HEAVY ORDNANCE. 165 going back to fundamental principles, and starting thence by well-con- ducted experiments. In England the government seems to have been satisfied, at first, to abide by the views and the skill of the distinguished engineer Armstrong ; but after a large experience and a heavy expenditure, another direction has been taken. In one of the recent French iron-clads, (the Belliqueuse,) I observed very heavy rifled cannon were mounted loading at the breech a system that has now lost favor with the English. *" There is also a greater inclination to rifle cannon in England and France than with us at the present time the experiences of battle having largely corrected that tendency in our navy. It is of national importance that these questions should be investigated in the only way that their nature permits that is, by experiment. We cannot take the conclusions of foreign powers, even if it were pos- sible to know what they agree upon ; but we must search for ourselves and be able, as well at) others, to carry the experience of the practice ground into battle. It is true that no pressing occasion seems to demand an immediate exertion. We are at peace, and there is no sign of a war to which we need be, or are likely to be, a party. But the great European family of nations is alive with the apprehension of approaching war, and no one can say at what instant its vast armies may be precipitated into deadly conflict. When this comes it cannot be art internal struggle, but will extend wherever the commerce or the distant possessions of civilization are to be found. Even so great a nation as the United States may be denied the priv- ilege of neutrality. Orders in council and imperial decrees will again, as of old, revive no peaceful discussion of the rights of belligerent and neutral which are involved in the practice of search, of blockade, and of contraband of war. How then shall our flag protect its neutral rights against the strong hand of the aggressor in every sea, if not by its ability to resist injustice when committed? Even the ordinary intercourse of peace frequently requires the inter- vention of our naval representative which, judiciously afforded, prevents accidental misunderstanding from acquiring importance by delay. The policy of the country always has been, and should be adhered to, that however small our naval force in peace, every vessel of it shall com- bine in itself the highest known qualities of a ship of war in armament, speed, and personnel. Then, in case of an emergency, it will not be diffi- cult to multiply these types to any extent. As ordnance is the distinguishing feature in this question, I hope that Congress will bestow the means which are now necessary to determine what it shall be when iron-clads become the objects of fire. From the report of Rear-Admiral Porter of the first attack on Fort Fisher. One or two leading vessels having made the mistake of anchoring too far off, caused those coming after them to commit a like error $ but when they all got in to place and commenced work in earnest, the shower of shell (115 per minute) was irresistible. So quickly were the enemy's guns silenced that not an officer or man was injured. I regret, however, to have to report some severe casualties by the bursting of 100-pounder Parrott cannon. One burst on board the Ticonderoga, killing six of the crew and wounding seven others. Another burst on board the Yantic, killing one officer and two men. Another on the Juniata, killing two officers, and 166 EXPERIMENTS ON HEAVY ORDNANCE. wounding and killing ten others. Another on the Mackinaw, killing one officer and wounding five others (men.) Another on the Quaker City, wounding, I believe, two or three. Another ontheSusquehamia, killing and wounding seven, I think. The bursting of the guns (six in all) much disconcerted the crews of the vessels when the accident happened, and gave one and all a great distrust of theParrottlOO-pounders, and (as subsequent events proved) they were unfit for serviceman d calculated to kill more of our men than those of the enemy. From the report of Rear-Admiral Porter of the second attack on Fort Fisher. I believe we have burst all the rifled guns left in the fleet one on the Susquehanna, one on the Pequot, and one on the Osceola and I think the reputation of these guns is now about ruined. WASHINGTON, D. C., February 6, 1867. SIR: I have the honor to transmit herewith the "Proceedings of a board of officers convened by virtue of Special Orders No. 29, War Depart- ment, Adjutant Generals 7 office, Washington, January 18, 1867." Yery respectfully, vour obedient servant, T. G. BAYLOR, Captain of Ordnance and Bvt. Col. U. 8. A., Recorder. Brevet Major General L. THOMAS, Adjutant General U. $. A., Washington, D. C. Proceedings of a board of officers convened in virtue of Special Orders No. 29, War Department, Adjutant General's office, Washington, January 18, 1867. Proceedings of a board of officers assembled at Washington, D. C., in pursuance of the following order, viz : [Special Orders No. 29 Extract.] WAR DEPARTMENT, ADJUTANT GENERAL'S OFFICE, Washington, January 18, 1867. # * # * # # * 15. A board of officers is hereby instituted for the purpose of determining the calibres, the number of each calibre, and the proportion of rifled guns which will probably be required for the armament of fortifications. Brevet Brigadier General William Maynadier, ordnance department; Brevet Major Gen- eral W. F. Barry, colonel 2d U. S. artillery; Brevet Major General J. G. Barnard, corps of engineers; Brevet Major General H. J. Hunt, lieutenant colonel 3d U. S. artillery; Brevet Major General H. G. Wright, corps of engineers ; Brevet Colonel T. G. Baylor, ordnance department. The board will meet at such time and place in this city as may be designated by the senior member. The junior member will record the proceedings. * * , * * * * * By order of the Secretary of War : E. D. TOWNSEND, Assistant Adjutant General. WASHINGTON, January 24, 1867. The board met in pursuance of the above order, and on the call of the senior member, at room No. 47 in the Ordnance Bureau, at 11 o'clock a. in. Present: 1. Brevet Brigadier General Win. Mayuadier; 2. Brevet Major General H. J. Hunt 5 3. Brevet Major General H. G. Wright. EXPERIMENTS ON HEAVY ORDNANCE. 167 Absent: 1. Brevet Major General W.F.Barry; 2. Brevet Major Gene- ralJ. G. Barnard; 3. Brevet Colonel T. G. Baylor. (Reasons not known.) After some discussion in relation to the information which should be procured for the use of the board from the Engineer and Ordnance Bureaus, the board, in consequence of the absence of the three remaining members, adjourned at 11.50 a. m., to meet at 11 a. m. to-morrow. H. G. WEIGHT, Brevet Major General, Recorder. WASHINGTON, January 25, 1867. The board met pursuant to adjournment. Present: 1. Brevet Brigadier General Wm. Maynadier; 2. Brevet Major General J. G. Barnard; 3. Brevet Major General H. J. Hunt; 4. Brevet Major General H. G. Wright; 5. Brevet Colonel T. G. Baylor. Absent: 1. Brevet Major General W. F. Barry. (Eeason not known.) Brevet Major General J. G. Barnard and Brevet Colonel T. G. Baylor reported themselves as having been detained by interruption of travel. The proceedings of the previous day having been read, some discus- sion was had with regard to the meaning of the order assembling the board, as to whether other than rifled guns were to be considered. It was, however, ascertained by reference to the letters of the Chief of Engineers and Chief of Ordnance, which brought forth the order conven- ing the board, that both smooth-bore and rifled guns were contemplated. The communication marked A, accompanying these proceedings, was read, having been referred to the board by the Chief of Ordnance. The board then adjourned till Monday, January 28, at 11 a. m., to await information from the engineer department with reference to the present armament of fortifications, and also the arrival of Brevet Major General W. F. Barry. WASHINGTON, January 28, 1867. The board met pursuant to adjournment, and the proceedings of the previous day were read, all the members being present. Brevet Major General W. F. Barry reported that he did not receive the order convening the board in time to reach here sooner. The board, after examining into and discussing the question of the calibres of guns required for our permanent works, adjourned at 2 p. m. until 12 in. to-morrow, to await further information from the engineer department. WASHINGTON, January 29, 1867. The board met pursuant to adjournment. Present all the members. The board, after some discussion, unani- mously recommend that the calibres of the heavy ordnance hereafter to be provided for the armament of permanent fortifications shall be: for smooth-bore, 20-inch, 15-inch, and 13-inch guns, and 13-inch and 15-inch sea-coast mortars; for rifled guns, 12-inch and 10-inch; and that guns of other than the above calibres now on hand be used in the positions for which they may be most suitable ; or in their present positions until they can be replaced by guns of the calibres above specified. Major General J. G. Barnard offered the folio wing 'resolution, which was adopted by the board, viz : Resolved, That, in the opinion of* the board, mortars may be made to play an important part in the defence of channels, as well as in prevent- ing anchorage ; and that, to ascertain what conditions are necessary to 168 EXPERIMENTS ON HEAVY ORDNANCE. their efficiency, experimental firings should be made to determine what force of iinpcct is necessary to break through the best protected decks of iron-clad*. The above resolution was amended by Brigadier General William May- nadier, and the amendment adopted by the board, as follows : Resolved, further, That, in the opinion of the board, it is of the highest importance that experiments should be made to ascertain the absolute relative power and efficiency of the 20-inch and 15-inch smooth-bore guns, and of the 12-inch and 10-inch rifled guns, against monitors and iron-clad vessels. At 3.15 p. m. the board adjourned till 12 m. to-morrow, and directed the recorder to procure a copy of the report of the board on armament of fortifications, made February 14, 1862, and approved by the honor- able Secretary of War March 27, 1862. WASHINGTON, January 30, 1867. The board met pursuant to adjournment ; all the members present. The proceedings of the previous day were read. Major General Barnard then offered the following resolution, which was adopted, viz: Resolved, That it is not expedient for this board to recommend the construction of any more 20-inch guns for service until their endurance and capabilities have been experimentally demonstrated. On motion it was resolved that in the opinion of the board, the Gatling gun, or a gun of similar character, may be advantageously adopted in place of the present flank defence howitzer. The board resolved to take up the plans of the fortifications in New York harbor for minute examination, in order to determine the general principles which shall govern in fixing the proper positions for rifle cannon, and thus enable them to arrive at the proper proportion of such guns. The board then adjourned till 12 m. to-morrow to wait for these plans. WASHINGTON, January 31, 1867. The board met pursuant to adjournment, and the proceedings of the previous day read. On motion it was resolved that a committee of three, to consist of one ordnance, one engineer, and one artillery officer, be appointed by the senior officer of the board to examine into such details of the plans of fortifications, and of the character of the approaches thereto, as may indicate the proper kind of guns, whether rifled or smooth- bore, to be placed in position, and to report the result of their examina- tion to the board as soon as practicable. The following named officers were appointed the committee by the senior officer of the board, viz : 1. Brevet Major General H. J. Hunt. 2. Brevet Major General H. G. Wright. 3. Brevet Colonel T. G. Baylor. The board then adjourned, at 1 o'clock p. m., until the committee were ready to report. WASHINGTON, January 31, 1867. The committee met in room No. 9 of the Engineer Bureau, at 1.30 p. m., and proceeded to examine the maps and plans of the forts designed for the defence of New York harbor. The armament for which pro- visions are already made or will soon be finished, for the forts at Sandy Hook and the battery near Fort Hamilton, was then fixed as follows: Sandy Hook. Sixty-nine 10-inch rifles, thirty- six 13-inch smooth-bore guns. EXPERIMENTS ON HEAVY ORDNANCE. 169 Battery near Fort Hamilton. Fifteen 12-inch rifles, two 10-inch rifles, fourteen 15-inch smooth-bore guns. The committee, at 4.15 p. m., adjourned to meet at the same place at 11 a. m. to-morrow. WASHINGTON, February 1, 1867. The committee met pursuant to adjournment, all the members present, and resumed the consideration of the armament of the forts for the defence of New York harbor. The following armament was agreed upon : Fort Wadsworth. Seventy-eight 10 -inch rifles, forty- three 13-inch smooth-bore guns, one 10-inch smooth-bore gun. South Cliff battery. Eleven 12-inch rifles, eight 15-inch smooth-bore guns. Battery Hudson. Ten 12-inch rifles, twelve 15-inch smooth-bore guns, two 10-inch smooth-bore guns. North Cliff battery. Twenty 15-inch smooth-bore guns. Castle Williams. Five 15-inch smooth-bore guns. Fort Columbus. Six 12-inch rifles, four 10-inch rifles, seven 15-inch smooth-bore guns, four 13-inch smooth-bore guns. South battery. Four 10-inch rifles, three 13-inch smooth-bore guns. Fort Wood. Seventeen 10-inch rifles, eleven 15-inch smooth-bore guns. Fort Gibson. Four 12-inch rifles. Fort Schuyler. Eight 12-inch rifles, fifty -three 10-inch rifles, four 15-, inch smooth-bore guns, seven 13-inch smooth-bore guns. The committee, at 2.30 p. m., adjourned till 11 a. m. to-morrow. WASHINGTON, February 2, 1857. The committee met pursuant to adjournment, all the members present, and after the proceeedings of the previous day were read, fixed upon the armament of the fort at Willet's Point as follows : Fort at Willet's Point. Eighteen 12-inch rifles, nineteen 15-inch smooth- bore guns. This completed the examination of the forts for the defence of New York harbor. The committee find, upon examination, that the x>roportion of rifled to smooth-bore guns thus determined upon is 15 to 13 ; but they would deem an equal division to be about the best distribution that could be made from their present knowledge of the capabilities of the two kinds of guns. The committee having finished the business before it, notified the senior member of the board that they would be, ready to submit their report to the board in full, session on Monday next, February 4, 1867. The committee then adjourned at 12.15 p. m. WASHINGTON, February 5, 1867. The board met at the call of the senior member at room No. 47 in the Ordnance Bureau at 12 m., all the members present. The proceedings and report of the committee having been read, the senior member pro- posed the question, shall the report of the committee be adopted"? The vote being taken, the report was adopted unanimously. The following remarks were then presented to the board by Brevet Major General J. G. Barnard: The board have investigated attentively the subject submitted to them and would respectfully state that the problem at the present 170 EXPERIMENTS ON HEAVY ORDNANCE. moment, " What shall be the probable absolute number of different cali- bres, and what shall be the proportion of rifled guns required for our fortifications," is peculiarly indeterminate. This will be apparent from the following considerations: Whenever armament boards have been heretofore convened, their duties have been, taking as fixed the number and emplacement of guns in the forts and batteries as prepared by the engineer department, to determine simply what guns shall be placed in them. In the case of the present board, however, it has first to deal with an entire new class of guns, of far greater power than those existing when the number of exist- ing "emplacements" was fixed by the engineer department. Second, with casemates and platforms not intended for such guns and generally illy applicable or inapplicable to them. Third, the modifications required in the works themselves, to enable them to receive our new guns and to resist modern artillery, are not yet determined upon by the engineer department, though in course of experimental investigation. A board of engineers, convened by the honorable Secretary of War in 1864, (and whose proceedings were approved by him,) to investigate the modifications required in our permanent works, recommended very important changes in the disposition of guns in our barbette batteries, suppressing plat- forms, introducing traverses, &c. ; while they at the same time emitted the opinion that the substitution of such guns as the 15 inch smooth- bore and corresponding rifle would justify a reduction in the total num- ber required. At the same time we believe that the relative capabilities of the smooth bore and heavy rifle (of heavy ordnance) have not been sufficiently investigated, experimentally, to enable an intelligent decision to be made as to the best proportion to be adopted. These remarks will, we think, show conclusively that any determination of the "number of each calibre an/1 proportion of rifled guns that will probably be required for our fortifications" would be at the present moment very illusory. The board have therefore contented thenisejves with reviewing the dif- ferent ports and harbors to be defended, and giving such a judgment as they best may, attaching no value to it as an ultimate determination, but merely as one which will enable the ordnance department to con- tinue in the best probable way its construction of guns. The vote having been taken as to the adoption of the foregoing remarks, resulted as follows: Ayes Brevet Major General W. F. Barry, Brevet Major General J. G. Barnard, Brevet Major General H. J. Hunt, Brevet Major General H. G. Wright, Brevet Colonel T. G. Baylor 5. Noes Brevet Brigadier General William Maynadier 1. The board is unanimously of opinion that for the permanent fortifica- tions there will probably be required, in addition to tiie ordnance now on hand: 15 20-inch guns, 190 15-inch gnus, 600 13-inch guns, smooth bores'; 200 12-inch guns, 610 10-inch guns, rifles ; 50 15-inch mortars, and 250 13-inch mortars; to be provided from time to time as the readiness of the forts to receive armament, the capacity of the foundries for its manufacture, and the appropriations applicable to its procurement may warrant. The board, at 1.45 p. m., adjourned till 12 m. to-morrow, to allow the recorder time to write up the proceedings. EXPERIMENTS ON HEAVY ORDNANCE. 171 WASHINGTON, February 6, 1867. The board met pursuant to adjournment; all the members present. The proceedings having been read to the board, they were signed. The board, at 12.30 p. m., adjourned sine die. WM. MAYNADIEE, Brevet Brigadier General U. 8. Army. WILLIAM F. BAEEY, Colonel 2d Artillery, Brevet Major General. J. G. BAENAED, Colonel of Engineers, Brevet Major General. HENEY J. HUNT, Brevet Major General. Lieutenant Colonel 2d Artillery. H. G. WEIGHT, Lieutenant Colonel of Engineers and Brevet Major General. T. G. BAYLOE, Captain of Ordnance and Brevet Colonel U. 8. A. A. BALTIMORE, MARYLAND, January 18, 1867. Whereas the duties prescribed to this board involve experimental tiring to determine how our existing works are to be modified, and whereas such modifications depend upon the character of the guns to be used ; and whereas a considerable number of our best sea-coast fortifica- tions are already constructed, having casemates in which it is impossible by any modification to introduce a 15-inch gun without diminishing much its traverse and leaving sections without casemate fire; and whereas, the English experiments show that the Palliser chilled iron shot is the most formidable projectile against iron defences, and that our own iron defences will be attacked by such or by steel projectiles : Resolved, That it be represented to the ordnance department that it is very desirable to have for such works, and perhaps for some others, a gun of nine or ten inches calibre, which, like the Woolwich 9-inch gun, will burn 40 or more pounds of powder, and throw at least a 250-pound projectile. Further, Resolved, That it be suggested to the ordnance department that pro- jectiles of this character be furnished for the 12 and 15-inch guns at Fort Monroe for our experimental firing. '"* * * * C. B. EEESE, Bvt. Brig. Gen., Captain of Engineers, Recorder. ENGINEER DEPARTMENT, January 22, 1867. Copy respectfully furnished to the Chief of Ordnance and recommended for favorable consideration. A. A. HUMPHEEYS, Chief of Engineers. 172 EXPERIMENTS ON HEAVY ORDNANCE. ORDNANCE OFFICE, January 25, 1867. Respectfully referred to the board on the armament of fortifications. A. B. DYER, Brevet Major General, Chief of Ordnance. A true copy : T. G. BAYLOR, Captain of Ordnance and Brevet Colonel U. S*A. [Endorsements. ] WASHINGTON, D. 0., February 6, 1867. T. G. Baylor, captain of ordnance, recorder, transmits proceedings of a board of officers, of which Brevet Brigadier General William Maynadier was president, convened to determine the number and calibre of guns which will be required for the armament of fortifications. Respectfully submitted to General Grant. E. D. TOWNSEND, Assistant Adjutant General. ADJUTANT GENERAL'S OFFICE, February 7, 1867. HEADQUARTERS ARMY, February 20, 1867. Respectfully forwarded. Approved. U. S. GRANT, General. AUGUST 28, 1867. Approved by the Acting Secretary of War. ED. SCHRIYER, Inspector General. ADJUTANT GENERAL'S OFFICE, Washington, September 4, 1867. Respectfully referred to Brevet Major General A. B. Dyer, Chief of Ordnance, with reference to the approval of the Secretary of War en- dorsed hereon. E. D. TOWNSEND, Assistant Adjutant General. EXPERIMENTS ON HEAVY ORDNANCE. 173 SCO 1C CO 00 ~^ 00 SO 1 ?. 55 1> O 50 8> 35 i ^3* t* Ci OS ti O5 O <^ 38 n f- o I > spnnoj ill 11 II 1! S^ooooooo ig <5 n3 n? *5 <5 *S*tr P40 1 IO O 1C J > CO O CC ' ) 00 00 GO r t^n n oo" c? t^"-*" r ||||g lO'0'fff )." 21 ,0000000000000000000000000 : :i i i ; i : -as i i ; i i i ; is i i :S i i I ill Mo la*."- il^'ll l ooc] .2"H.a 0.0. 65355 -aod 174 EXPERIMENTS ON HEAVY ORDNANCE. EXPERIMENTS ON HEAVY ORDNANCE. 175 % APPENDIX D. TECHNICAL AND MISCELLANEOUS EXTRACTS. INITIAL TENSIONS. Extracts from u experiments on metals for cannon and cannon poivderj 7 * Rodman, page 96. The solid gun, cooling from the exterior in an open pit, and being of iron that contracted very much in cooling, was doubtless thrown upon a very heavy strain, the exterior being compressed and the interior elon- gated $ while the hollow gun, being rapidly cooled from the interior and prevented from cooling from the exterior, was thrown upon a strain just the reverse of the solid one. And I have no doubt that the interior of the solid gun was broken before the exterior was relieved from the pres- sure to which it had been subjected in cooling; while in the hollow gun the great object of my improvement was in part, if not fully, attained, viz., to throw the gun upon a strain, such, that under the action of the law of strain, as stated above, each one of the infinitely thin cylinders composing the thickness of the gun shall be brought to the breaking- strain at the same instant. This condition would give us for the effective resistance to rupture in a gun one .(1) calibre thick, 2#, instead of fa which has been shown to be all that could be obtained from a gun free from strain by cooling and is, doubtless, much more than can possibly be attained in practice. The higher the metal, and the greater its con- traction in cooling, and the more rapidly the gun is cooled, the further will the solid one fall below a, and the more nearly will the hollow one approach 2a, provided the cooling be effected from the interior ; also, the greater the diameter of the solid gun, the greater will be the strain from cooling. It is not considered practicable to cool a gun so rapidly from the interior as to cause rupture to commence on the exterior. Extract from the report of the Joint Committee on the Conduct of the War. The Dahlgren gun is the invention of Eear- Admiral John A. Dahlgren, and is distinguished by its exterior form. The plan adopted to avoid the strain consequent upon cooling a solid casting of large size from the out- side is to make the casting considerably larger than would otherwise be needed to produce a gun of the required size, anneal it after cooling, and then turn it down to the proper size and form. But the Dahlgren guns of the largest calibre are now being manufactured upon the Eodman principle. The Rodman gun, while having to some extent its peculiarity of form, is principally distinguished by the mode adopted in its manufacture, which is an invention of Major T. J. Eodman. The casting is made around a hollow core, or core-barrel, as it is termed, into which is intro- duced a stream of cold water, the outside of the casting being kept heated until the cooling from the interior reaches the outer portion of the mass of metal forming the casting. This mode of manufacture, it is claimed,, insures two important advantages over the old method of casting the gun solid and then boring it out. The strain upon the metal produced by cooling in large masses is reversed, rendering the gun less liable to burst from the explosion of the powder in it ; and a much greater degree of hardness is given to the interior surface, rendering the gun less liable to abrasion in the bore by the passage of the projectile along it and the action of the gases ^of the powder upon the metal. It is generally held by the witnesses ,that no effective gun of large calibre can be made of cast iron except upon the Eodman principle, or the principle of cooling from the interior. 176 EXPERIMENTS ON HEAVY ORDNANCE. Extracts from Mallet on Artillery. SEC. 32. A certain amount of contraction on becoming solid from the liquid state occurs in all castings. It is well known to practical found- ers that for cast iron this is variable, and depends upon the mass of the casting, being greatest for small and least for large castings of the same "make" of iron; but it is obvious, and it follows from Mr. Bolley's researches, that the contraction also will be greater in proportion as the metal' is poured into the mould at a higher temperature, although, from the expansion in the act of crystallizing, the specific gravity of the solid mass maybe less at the higher than at the lower temperature of" pouring. 7 " SEC. 33. As, therefore, there are two conditions that principally affect the degree of contraction the total change of volume between the liquid metal and its solid casting, namely, the extent to which the fluid metal as entering the mould has been expanded by elevation of temperature and the state of final aggregation of the crystalline particles, which we have seen depends much upon the former so there will be a determinate amount of contraction due to a determinate thickness or mass of casting, irrespective of, though "also related to, the co-efficient of contraction for any particular "make" of iron; for there is no doubt that different makes, cceteris paribusj contract somewhat differently. From whenc.e it follows that different parts of the same casting, if differing materially in scantling or mass, will have different amounts of final contraction. SEC. 34. Sudden changes of form or of dimensions in the parts of cast-iron guns, besides the injury they do to the crystalline structure of the mass, introduce violent strains, due to the unequal contraction of the adjoining parts, whose final contraction has been different. How desirable is it, therefore^ to introduce such alterations of the forms of our ordnance as shall avoid those sudden and enormous (and often useless) changes of adjacent mass, that we observe; as for example, in the sea and land service 13-inch mortars, where at the chamber (where the strain being as D is least) the thickness of metal suddenly approaches twice that of the chase a malconstruction the full evils of which we have yet to consider. SEC. 35. The amount of lineal contraction due to solidification of cast- iron, appears to vary with metal and circumstances of casting, from T i s up to gL of the dimensions of the cold mass. Its contraction in volume, therefore, (more than three times this,) and probably not equal in the directions of three rectangular axes, owing to the christalline struc- ture, is so great, and the difference such, between its measure for large and small parts of the same casting, that the latter never should be neglected. SEC. 43. Besides the effects already referred to, due to the contrac- tion of cast-iron in becoming solid, another class of abnormal strains introduced by the consolidation of one portion of a casting before another must not be passed over, as often producing results of the most import- ant character in artillery. This will be more readily understood by immediate reference to example. When a large gun, or, still more, a large mortar, is cast solid, and the metal cools in the ordinary way, the external portions solidify long before the interior has ceased to be liquid, and the process of solidification is propagated, as it were, in parallel "couches" from the outside to the centre of the mass. The lineal con- traction of any one couch assumed of indefinite thickness is in the direction of its circumference directly proportionate to that circumfer- EXPERIMENTS ON HEAVY ORDNANCE. 177 ence; and so it would seem (at first) that the contraction of the whole assemblage should be at every point proportionate to its distance from the centre, and that so the solid when all cold, should be left in a state of molecular equilibrium. This is not the case, however, for no sooner has the first couch or thickness of solid crust formed on the exterior, than it forms a complete arch all around, so that the contraction between fluidity and solidification of each subsequent couch is accommodated (the continuity of the mass remaining unbroken throughout) by portions of matter withdrawn radially from the interior toward the still cooling exterior; that is to say, from a smaller towards a larger circumference. SEC. 53. Unequal cooling, especially if very rapid, involves all the injury that violent internal wrenching and straining can do to strength, strains of the very same character as those under which it is part of the purpose of this paper to show, that guns burst, and which often, in the every day practice of the iron-founder, result in actual fracture. Extract from the testimony of Brigadier General George D.Ramsey Before the Joint Committee on the Conduct of tlie War. Q. In what does the patent consist in this Eodman gun for which this royalty is paid by the government to Mr. Knap ; and in what does the difference consist between that gun and guns cast in the common or ordinary mode ? A. Heretofore all cannon were cast solid and allowed to cool in the casting pit. In this way the cooling of the fluid metal from the exterior extended gradually towards the inside, which was the last part that solidified. The shrinkage by this mode of cooling tended to separate the interior layers of metal from the exterior. In Hodman's plan, the patent consists of cooling from the interior and keeping the outside hot; the shrinkage begins on the inside of the mass, and each layer of metal as it cools shrinks upon the nearest interior layer, thus binding all the successive layers together. Extract from Ordnance and Armor, " Holly? p. 234. 278. I. Increasing the thickness of the walls. The most obvious means, of enabling any vessel to sustain a greater elastic pressure, such as the gas of exploded gunpowder, is to simply thicken its sides, thus increasing the area of substance to be torn asunder. This rule is founded upon the practical facts of every-day engineering, which usually deal with com- paratively low pressures and thin walls. Even in case of guns of small calibre it has proved tolerably safe. But when these conditions are greatly changed when the problem is, for instance, to throw projectiles of 13 to 15 inches diameter at the rate of 1,500 to 1,800 feet per second, and the gun is proportionally thickened to stand the excessive strain due to both the increased pressure per square inch and the increased num- ber of square inches pressed upon, another law, unobserved in ordinary practice, assumes a very serious importance. This law is thus clearly explained by Captain Blakely : * 279. To obtain much greater strength by casting guns heavier is impossible, because in cast guns (whether of iron, brass, or other metal,) the outside helps but very little in restraining the explosive force of the powder tending to burst the gun, the strain not being com- municated to it by the that intervening metal. The consequence is in large guns the inside is split, while the outside is scarcely strained. This split rapidly increases, and the gun ultimately bursts. This will be more easily understood by considering the case of a much more elastic tube; for instance, an India-rubber cylinder, 10 inches in internal diameter and 10 inches thick, therefore 30 inches in external diameter. Such a cylinder might be strained by pressure * A Cheap and Simple Method of Manufacturing Cannon,. 1858. Eep. No. 266 12 178 EXPERIMENTS ON HEAVY ORDNANCE. Fig. 131. Fig. 132. from within till the inside stretched to double its original circumference. The diameter would, of course, also be doubled, and would be 20 inches instead of 10. Now it is evident that the outside circumference and diameter cannot be doubled at the Fig. 130. same time, or else the latter must become twice 30 or 60 inches which would give a thickness of 20 inches, quadrupling the mass of material, which is impossible. A moment's reflection shows that the thickness must diminish as the circumference is increased by pressure from within, for if the thickness remain 10 inches when the internal diameter has become 20, the external diameter must be 20 plus twice 10, or 40 inches. This could not be unless we imagine w r hat seems impossible, viz, that the bulks of the material is considerably enlarged, as each inch in length of the cylinder would now contain 1,200 cylindrical inches, (the differ- ence between the squares of 40 and 20, the external and internal diameters,) whereas, originally, it only contained 800 inches, the difference between the squares of 30 and 10. Yet, even if the thickness could remain the same, notwithstand- ing the increase of circumference, the outside layer could only be strained one-third as much as the inside one, because three times as long. The same elongation, which w r ould cause a strain of one ounce or one pound in the longer circumference, would cause a strain of three ounces or three pounds in the shorter one, and the elongation which would but moderately strain the one would break the other. This reasoning is equally applicable to the minute extension of iron ; the increase of one-tenth of an inch in the outer circumference of a 10-inch gun being possible without fracturing that part, being an elongation of but one in 940 ; whereas the same extension must crack the inside, as no iron could stand an elon- gation of one-tenth in 31^, or one in 314. Even on this showing, then, the outside of a thick tube cannot do its share of work ; a closer examination, however, must con- vince us that this is an over-estimate of it, for the thickness of mate- rial must diminish as the circumference is increased. When the inner diameter of the 10-inch cylinder becomes 20 inches, the thickness must diminish from 10 to 7.32 inches, the cross-section of the cylinder remaining the same. This cross-section was originally 800 circular inches, 800 being the difference between the squares of 30 inches, the inner, or 900 minus 100. When stretched the area of the cross- section must continue to be 800 round inches. Now a thickness of 7.32 inches gives us an external diameter of twice 7.32 or 14.64 added to 20, the internal diameter, in all 34.64 inches, the square of which is 1,200. Subtracting 400, the square of 20 leaves 800 round inches as before. In this case the outside of the cylinder is stretched but 4.64 in 30, about one in seven, when the inside is stretched to double its original size. If the inner diameter be only stretched to 11 inches the thickness must be diminished from 10 to 9.674 inches, the outer diameter becoming 30.348 inches, the cross-section remaining 800 round inches, as before, the difference between the squares 30.348 and 11. Here the outer layer is elon- gated .348 in 30, or 1 in 86; whereas the inner is extended 1 in 10, showing a strain or an exertion of power 8 times greater. In the minute extension of metals the disproportion is still more striking. Thus in cast-iron the 10-inch inner diameter may become 1 OTCRJ? which wou ld extend the outer diameter only from 30 to 30^^, the cross-section remaining 800 inches, and the thickness dimin- ishing from 10 inches to 9|t)o. Here the outside would only be stretched ^^ in 30, or 1 in 9,000, the inside being stretched yjj^ in 10, or 1 in 1,000, exerting, therefore, nine times as much power a? the outside. It is evident that a slight increase of pressure from within would break the inside, while the outside could help but little in restraining the disruptive force. 280. If we make equidistant circular marks on the end of an India-rubber cylinder, (Fig. 134,) and stretch it, we can see plainly how much more the inside is strained than the outside India-rubber cylinder, with or cven the intermediate parts. The spaces between the marks equidistant concentric marks, will become thinner, each space becoming less thin than that inside Fig. 133. EXPERIMENTS ON HEAVY ORDNANCE. 179 The same cylinder stretched by Fig. 136. Cylinder burst by internal pres- of it, but the inner space much thinner than the other?, (see Fig. 135. Fig 135,) showing that when the inside is strained almost to breaking, the intermediate parts are doing much less work, and those far removed almost none. 281. Law of strength of cylinders. In the first volume of the "Transactions" of the Institute of Civil Engineers, p. 133, there is a naper by Professor Peter Barlow, F. R. S., on the Strength of Cylinders. The law he deduces is, that "in cylinders of metal the power exerted by different parts varies inversely as the squares of the distances of the parts from the axis." Thus, in a 10-inch gun, when the inside, which is five inches from the axis, is fully strained, the metal two inches from the inside, or seven inches from the axis, can only exert a force f f , or little more than half as much ; three inches further, ten inches^ from the axis, the force exerted diminishes to &, or but a Barter of that exerted by the inside ; and if the gu be twelve inches thick, the outside, which is seventeen inches from the of the exterior. axis, can exert but ^ 9 , or about ^ as much power as the inside. Of course, casting the gun still thicker would add but very little to its strength ; we cannot, therefore, be astonished that it has been found in practice that cylinders for hydraulic presses, with a thickness equal to about one-half the diameter of the piston, are very nearly as strong as if ten times as thick. 282. In 1855, Dr. Hart, of Trinity College, Dublin, investi- gated the problem. His calculations (see note W, p. 259, of Mr. R. Mallet's work on the Construction of Artillery) give greater strength to the inner parts, but still less to the outer, than those of Professor Barlow. Both these gentlemen, as well as General Morin, and Dr. Robinson, the astronomer, who have also studied the question, agree that no possible thickness can enable a cylinder to bear a pressure from within greater on each square inch than the tensile strength of a square inch bar of the materiul; that is to say, if the tensile strength of cast-iron be sure. six tons per inch, a cylinder of that metal, however thick, cannot bear a pressure from within of six tons per inch. 283. The report of experiments made by the United States govern- ment in bursting hollow cylinders by internal pressure states that "the general range of the results appears to sustain Mr. Barlow's hypothesis. 7 '* 284. In further proof of the foregoing facts. Captain Blakely cites the actual fracture of some cylinders (Fig. 136) made by Mr. Longridge, of iron wound with wire. The cracks were u much more open at the inside, and some not extending to the outside." 285. The law of diminution in the power of resistance is also illustrated by Professor Treadwell, who states it as follows :t Suppose such a cylinder to be made up of a great number of thin rings or hoops, placed one within another. Then the resistance of these rings, compared one with another, to any distending force, will be inversely as the squares of their diameters. If we make a cylin- der of 4 1 concentric hoops of equal thickness, disposed one within another, and exactly fitting, so that the particles of each hoop shall be in equilibrium with each other, the diameter of the largest being five times that of the smallest, then the force of each, beginning with the inner- most, to resist distension, will be represented by the following numbers : 1000 ........ 444 ........ 250 ........ 160 ......... Ill ......... 82 ......... 62 ......... 49 826 ........ 391 ........ 225 ........ 148 ......... 104 ......... 77 ......... 59 ......... 47 694 ........ 346 ........ 207 ........ 137 ......... 98 ......... 73 ......... 56 ......... 45 591 ........ 309 ........ 189 ........ 128 ......... 92 ......... 69 ......... 54 ......... 43 510 ........ 277 ........ 174 ........ 119 ........ . 87 ......... 65 ......... 51 ......... 41 ......... 40 An inspection of these numbers must, I think, impress any one with the fact that it is impossible to increase essentially the strength of cannon by a simple increase of thickness. 286. The weakness of a homogeneous cylinder, and the remedy, (which will be considered in the following article,) have been mathematically investigated, with great care, by Dr. Hart, of Trinity College, Dublin, * Reports of Experiments on Metals for Cannon ; 1856. t "The Practicability of Constructing Cannon of Great Calibre,' &c. ; 1856. 180 EXPERIMENTS ON HEAVY ORDNANCE. and Mr. C. H. Brooks, from whose calculations it has been illustrated and made the subject of a paper by Mr. James Atkinson Longridge, followed by an important discussion before the Institution of Civil Engineers. Mr. Longridge says:* If, in Fig. 137, A B C D represent a portion of a section of an 8-inch gun, of which A G B is the inner, and D F C the outer circumference, the state of tension of any particle between G and F may be denoted by ordinates drawn at the points in question, those above G F representing tension, and those below compression. If now the gun be of any homogeneous material, such as cast-iron, the state of tension at the time of explosion, and when the gun is about to burst, will be denoted by a curve H I. Fig. 137. Hlustrating a strain on a homogeneous gun. or II i, the former calculated according to Professor Hart, and the latter according to Pro- fessor Barlow's formula. Then, supposing the tensile force of the material to be 12 tons per square inch, and the thickness of the gun 64- inches, when the strain at G is G H, or 12 tons, at F it is F 1 = 3 tons, or F i== If tons, according as the one or other formula is adopted. The areas of these curves give the total strengths of the gun at the bursting point, and are found to be 36.72 tons and 30.871 tons respectively, instead of 78 tons, which it would have been if uniformly strained at 12 tons per square inch. 287. II. Hoops with initial tension to resist elastic pressure. This sys- tem consists in making a gun of concentric tubes by putting on each successive layer, proceeding outward from the centre, with an initial tension exceeding that of those below it, or so that each hoop or tube shall compress what is within it. The inner layer is thus, in its normal state, in compression, while the outer layer is in the highest tension. Then, by the law illustrated in the foregoing paragraph, the inner layer being in compression is able to sustain the first and greatest stretch, and the outer layer, although stretched less by the explosion of the powder, has already been stretched into high tension, and thus has to do an equal amount of work. The intermediate layers bear the same relations to the initial strain and the strain of the powder, so that, in short, all the layers contribute equally of their tensile strength to resist the strain of the explosion. * "Construction of Artillery," Inst. C. E , 1860. EXPERIMENTS ON HEAVY ORDNANCE. 181 ON LARGE CAST-IRON GUNS. From tJie Army and Navy Journal. The interest awakened by the previous extracts we have made from the advance sheets of General Gillmore's report induces us to continue them this week. We select the generaPs remarks on cast guns of large size: A safe and advantageous arrangement and distribution of the materials of a large cast gun particularly of a rifle-gun to enable them to sustain the successive strains and shocks to which they will be subject in firing, is incompatible with the condition that the gun shall be composed of a single piece of homogeneous nietal. With forged guns of good wrought iron, like that from Salisbury, Connecticut, the case is somewhat different, particularly if the workmanship be such that the piece will not first give way at the welds. The greatest tensile strength and ductility of the metal are both brought into action. In firing, the bore of the gun rap- idly receives a permanent enlargement, within the limit of rupture. The surrounding metal is thus placed under tension, and the piece strength- ened to a certain extent. The further stretching of the bore, beyond the power of the metal to bear, is thereby prevented. In a wrought-iron gun there is very little enlargement of the bore after the first fifty rounds, if fired with heavy charges. Such guns should first be bored a little smaller about two-tenths of an inch than they are required to be, and should then be fired with a few large charges, and re-bored to the proper calibre. The forces which act upon a gun, tending to destroy it, are due prin- cipally to the explosive force of the powder, and the expansion of the gun by heat. In smooth-bore guns, the maximum force of the powder or, in other words, the maximum pressure blowing out in front of the reinforce was in consequence of the inadequate length of the latter. It is known, from repeated experiments, that the distending strain upoD the metal of a gun, at points equally distant from the muzzle that is, within the same transverse circular section varies inversely with the squares of the distances of those points from the axis of the bore. Thus, at five inches from the axis, the strain upon the metal would be about double what it would be at the distance of seven inches, or in the ratio of 49 to 25. If we suppose a cylinder to be made up of a great number of very thin concentric cylinders, in a condition of initial molecular repose, then the strain upon these several cylinders, due to any distending force equally distributed over the inner surface of the inner one, would vary inversely with the squares of their diameters. Professor Treadwell illustrates this law of diminution in the following manner: "If we make a cylinder of 41 concentric hoops of equal thickness, disposed one within "another, and exactly fitting, so that the particles of each hoop shall be in equilibrium with each other, the diameter of the largest being five times that of the smallest, then the force of each, beginning with the innermost, to resist distension, will be represented by the following numbers : 1000 444 250 160 Ill 82. 62 49 826 391 225 148 104 77 59 47 694 346 207 137 98 73 56 43 591 309 189 128 92 69 54 45 510 277 174 119 87 65 51 41 ...40 182 EXPERIMENTS ON HEAVY ORDNANCE. There is another important fact deduced by mathematical calculation, and sustained by experiments in both this country and Europe, viz: that no increase of thickness, however great, can enable a homogeneous cylinder to sustain a distending pressure from within, on each square inch, exceeding the tensile strength of a bar of the material one inch square. Hence it is useless to attempt to augment the strength of a gun by increasing its thickness beyond a certain point, " because," as Captain Blakely remarks, "in cast guns (whether of iron, brass, or other metal) the outside helps very little in restraining the explosive force of the powder tending to burst the gun, the strain not being communicated to it by the intervening metal. The consequence is that, in large guns, the inside is split ivhile the outside is scarcely strained. This split rapidly increases, and the gun ultimately bursts." In other words, the exterior part of a homogeneous gun gives way to forces applied by wedging and leverage, and not to a transmitted tensile strain. We see, therefore, how inadequately the hooping of old and nearly expended guns accomplishes the object in view, of conferring upon them additional powers of endurance, since the exterior hoop simply reinforces metal that has not only never had its strength impaired by use, but is not liable to be brought under any strain exceeding that which it is well able to bear, except a splitting from the inside, which a hoop can but feebly if at all restrain. The only apparently effective way to utilize the strength of the exterior, unimpaired metal of a cast gun in which cracks have already appeared on the inside, is to replace a portion of the inside metal, throughout the entire length of the bore, by a tube of tough and elastic material, placed under slight compression by cooling the gun upon it. Initial tension. We would conclude from the foregoing that if a gun be compounded of several thin concentric hoops, or cylinders, those on the exterior being under suitable initial tension, increasing according to a fixed law with their several distances from the common axis, so that the aggregate of the initial tension and transmitted strain, per square inch on each cylinder, would be just equal to the tensile strength per square inch bar of the metal, we would obtain a combination satisfying the requisite conditions of maximum strength against statical pressure ; for a distending force which would rupture the inner cylinder would rupture all the others at the same moment. The greater the number of cylinders, their aggregate thickness remaining constant, the greater would be the strength of the combination. Varying elasticity. Let us take another view of the case. If the several thin cylinders be composed of metal possessing different degrees of elasticity, decreasing according to a fixed law from the interior toward the exterior, so that those on the inside would, by their greater elastic expansion, transmit externally a distending strain of such intensity that the metal of the several cylinders would reach the limit of elasticity at the same moment, we would then have a combination of maximum stat- ical strength, so long as the strain was not great enough to give the metal a permanent set; that is, so long as the elastic limit was not exceeded. When that point is reached, the advantages of varying elas- ticity partially disappeared, and are replaced, in a measure, by those of varying tension. A cannon compounded of many concentric cylinders, combined on either of the foregoing principles of initial tension or varying elasticity, although possessing great theoretical strength, and although capable in practice of sustaining great statical pressure from within, (great, indeed, EXPERIMENTS ON HEAVY ORDNANCE. . 183 in proportion to the number of cylinders used for a given aggregate thickness,) does not possess sufficient unity of form to withstand the repeated shocks of firing. While there must be, in some degree, a division of parts, in order that the conditions necessary to resist statical pressure may be imposed to a certain extent, there must also exist in cannon the requisite continuity of mass and structure to resist the instantaneous wave of force and other vibrations created in firing. Cannon are seldom constructed of as many as four cylinders ; generally of not more than two of three. Captain Blakely has attempted to combine the distinct advantages of varying elasticity and initial tension by using three tubes. The two inner tubes are of steel, that possessing the greatest elasticity forming the bore, while the outer tube is of cast iron, on which the trunnions are cast. The tubes are shrank together, so that the outer one is under slight initial tension. The elastic limit of the inner steel is thus favored by bringing it under slight compression. Even should the steel tubes become permanently strained, the gun, if properly constructed, would not be weakened thereby, as the effect would be simply to increase the tension upon the cast-iron jacket. Captain Palliser makes use of this principlejin bringing his large guns under suitable tension on the exterior. He makes the inner tubes of soft metal, the most ductile one containing the bore, and then fires the gun with a charge that will permanently stretch the inside. The gun is then finished by re-boring to the proper calibre. Of course the exterior cylinder is thus placed under initial tension. Major Eodman, of the ordnance department, United States army, recommends a method, now extensively followed, for placing the metal of cast-iron guns under the proper conditions of initial tension, by cast- ing them hollow and cooling them from the inside ; a process which is inapplicable to steel guns, which have to undergo annealing. In 1856 Professor Treadwell proposed a method of "constructing can- non of a large calibre," of several tubes, the inner one, containing the breech, being of cast iron about half a calibre in thickness. Upon this he placed "rings or hoops of wrought iron, in one, two, or more layers," by screwing them on. For that purpose a screw or thread was cut upon the exterior of the inner or cast-iron tube, and upon the interior and exterior of the other tubeSj except the outside of the outer one. The hoops are about one-thousandth part of their diameter less than the parts they envelop, and are screwed to their places while hot, to secure the proper tension. Whether the tubes of a compound gun should be put together on Professor Treadwell's plan, with screws, or whether a more simple and less expensive method of combination will .give the requisite unity of form, is still a question of discussion. For reasons which will not be given here, it is believed that screws are unnecessary, especially if the trunnions are placed upon the outer tube, as in the Blakely and Whit- worth guns. Uffects of heat. The heat generated by the burning charge induces or increases compression on the inside and tension on the outside of a gun; and therefore, within certain undefined limits, strengthens the piece against a distending strain. Another kind of strain is brought upon the exterior of the gun by the expansion of the bore longitudinally. Against this, a gun composed of two or more tubes can accommodate itself with less danger of injury to the exterior than if made from a single piece of metal, for the interior tube, instead of forcing the exterior to elongate with it, or yield to rupture, slips through it. 184 EXPERIMENTS ON HEAVY QRDNANCE. The composition of the armament of land batteries for channel defence, in the present condition of the great question of ships against forts, should, of course, have special reference to the defence against armored vessels. The best proportion for the two kinds, rifles and smooth-bores, the most advantageous calibre for smooth-bores, whether large or medium size, or a mixture of both, are questions upon which a diversity of opinions exist among military and naval men. The invention of a large gun of 12 or 15 inch calibre sufficiently strong to be used effectively as a rifle, and rifled in such a manner as would not impair its qualities as a smooth- bore, would be a great advance in artillery. With such a gun heavy elongated projectiles would be used with comparatively low velocities, at either long or short range, for their smashing effect upon armor, while solid steel or cast-iron spheres, and bolts and long percussion shells at high velocities, would be very destructive in cutting and punching through armor, and also upon the men and guns and machinery inside. Batteries for channel and harbor defence should contain some but in what proportion I am not prepared to suggest of the largest calibres that can be manoBuvred with ease and rapidity. For cutting through unimpaired armor at short range, in order to reach vital parts within as quickly as possible, smaller calibres are better, as they will stand greater relative charges and yield higher velocities safely. EFFECT OF SIZE OF MASS ON STRENGTH AND TEXTURE OF CAST-IRON. Extract from Mallett on Artillery. SECTION 24. It is known to every practical iron-founder upon a large scale that generally the larger the mass of casting he makes with any given quality of cast iron the " coarser is the grain? that is, the larger are the crystals that develop themselves in the mass. SEC. 30. That the lower the temperature at which the fluid cast iron is poured into the mould, and the more rapidly the mass can be cooled down to solidification, the closer will be the grain of the metal; the smaller its crystals the fewer and least injurious the " planes of weakness," and the greater the specific gravity of the casting cceteris paribus. SEC. 50. Slow cooling develops a coarse, uneven grain, with large but thoroughly irregular and confused crystallization. Cast iron with such a grain is never strong or cohesive, though, perhaps soft and extensible. The more rapidly a casting once consolidated can be cooled, without introducing injurious effects, the finer, closer, and more even will be its grain on fracture, and with any given metal the greater will be its strength. The rate of cooling cannot be accelerated beyond a moderate limit. If this limit be exceeded, as by casting in a cold, thick, highly conducting metallic mould, the iron is "chilled," its chemical or at least its mixed constitution changed, and the uncombined graphite is exuded, the combined carbon only remaining in the white chilled metal. It can- not be so fast as to endanger unequal contraction, nor must it be so fast in large castings, such as guns, requiring to be a fed" from a " feeding head" with fresh portions of hot fluid metal during consolidation to fill up the internal cavities or porosity due to contraction and crystallization, as already explained, that this feeding cannot be accomplished. The prevalent notion, however, that the soundest and strongest castings are obtained by letting them cool slowly in the moulds is founded on a radi- cal error. EXPERIMENTS ON HEAVY ORDNANCE. 185 RELATION OF SIZE OF MASS TO STRENGTH AND TEXTURE OF WROUGHT IRON. Extract from Mallett on Artillery. SECTION 213. We have found that the effect of large increase in the mass of wrought iron, in connection with its necessary or exisitiug modes of manufacture, is to prevent by process any regular or uniform arrange- ment of its integral crystals; that as such masses are necessarily continued long heated while forging, occupy long in cooling, and con- tract considerably in all their dimensions in cooling, so the crystals are developed to a large size and become arranged to a greater or less extent in directions transverse to the surfaces of external contour of the mass. The results are irregular " planes of weakness," reduction of ultimate strength to resist a quietly and steadily applied tensile force of from 20 to 17, or in very large masses of from 5 to 4 in round numbers, and reduc- tion of resisting power to such impulsive forces as are concerned with artillery in the ratio of from 7J to 1, or probably even more; for a train of difficulties are introduced in the manufacture, and of injuries done to the chemical qualities of the material, in proportion as we continue to increase the magnitude of the mass to be forged. SEC. 214. When the mass exceeds a very moderate bulk (in breadth and thickness) the processes of rolling, &c., are at an end; those of forg- ing by the tilt or steam-hammer alone are available. Skilled labor and all the mishaps to which the results of the most adroit workmanship are exposed in dealing with the heating and hammering of vast and scarce manageable masses are inevitable. The mass must be gradually built up and aggrandized in size by continual welding on to it of small pieces, involving reiterated heating and partial cooling ; exposure for weeks, perhaps, to a temperature at which the exterior of the mass gets changed more or less in chemical constitution, and at each welding the risk of inclusion of more or less slag, cinder, or other foreign matter. Late experience has shown me that in very large cyliiidric masses of forged wrought iron, (i. e., of three feet diameter and upwards,) amongst the other abnormal circumstances involved in their production, is that of their frequently* rending or tearing, internally, in planes nearly parallel with and about the axis, though not always in it, presenting characters similar to those described in section 217; and the cause appears to be that in the progress of cooling of such a mass the exterior cools first and becomes rigid, while the internal portions are still red-hot and soft. The external parts would contract as they cool, but they already grasp, in perfect contact, the still hot interior; the exterior, therefore, cannot contract fully, but becomes solid under constraint cir- cumferentially, partly itself extended in virtue of its compressing the still hot and soft interior; the latter at length also becomes cold and rigid, but its contraction is now resisted by the rigid arch of the exterior with which it is surrounded. The contraction of the interior, therefore, is limited to taking place radially outwards from the center, and thus the mass rends itself asunder in some one or more planes parallel to the axis of the cylinder. In a cylindric mass of forged iron, varying from 24 to 36 inches in diameter, rents of 18 inches in width across a diameter were found with jagged counterpart surfaces clearly torn asunder, and about three-fourths of an inch apart at the widest or central part; and the fact is most instructive as to the enormous internal strains that must exist from like causes in cast-iron guns and mortars of large size. 186 EXPERIMENTS ON HEAVY ORDNANCE. It is probably from this cause that more or less hollo wness is found in the centre of almost every large forging, greater in proportion as it is larger. The difficulty is one not easily overcome; very slow, and, as far as possible, uniform cooling of the whole mass in an annealing oven sug- gests itself as one; but this has disadvantages in enlarging the crystal- line development of the metal, or providing a central cylindric opening so as to cool both the circumference and the center together. EFFECT OF RE-MELTINGS ON THE STRENGTH AND TEXTURE OF CAST- IRON. Extract from Nallett on Artillery. SECTION 25. The experiments of Mr. Fairbairn (Trans. Brit. Ass., 1853) on the repeated melting of the same cast-iron, by casting into inch square bars, are concluded by him to prove that the grain of the metal and the physical qualities of the casting improve by some function of the number of meltings, and he fixes on the 13th melting as that of greatest strength. EFFECT OF HEAT ON GUNS. Extract from Mallett on Artillery. SECTION 89. Applying Professor Hodgkinson's experimental results as to the extensibility of cast-iron under strain to this reasoning, and taking the coefficient of expansion by heat for cast and wrought-iron as the same for low temperatures, (strictly as 1000893, 1000894 for tempera- tures under 212,) we have the extension for cast iron for the square inch of section equal about 3^0 -Q of its length for each ton of load, up to seven or eight tons, at which its elasticity becomes permanently im- paired ; that is to say, when it begins to lose its form. An equal change of length is due to eight degrees of Fahrenheit difference in tempera- ture. SECTION 90. Let us now assume a 64 pound shot rammed home at 2,000 Fahrenheit, which is under a Avhite heat, and that it remains 50 seconds in the gun while the latter is being run out and fired; that in this interval the shot transmits T ^ of its heat to an equal mass of the cold gun, and that the whole of this is operative in expanding a cylin- dric ring of a determinate thickness around the ball, then we have F=^ =25 tons, as the mean compressive strain per square inch upon this interior ring. But as the ultimate cohesion of cast iron does not exceed about eight tons to the square inch, the actual effect upon the strength of the gun is the same, as if about three inches of its thickness were removed, or that an inch in thickness of its interior metal were removed, and a total strain of 17 tons were at the same time visited upon the remaining section of its thickness. At such a conjuncture, with such a steady strain already on its metal, the gun is fired and an additional impulsive strain, equal to the work done in giving to the shot its initial velocity, is suddenly brought upon its material. This, even with the regulation reduced charge for hot shot, of J the service charge for cold shot, is seldom less than 2J tons on the square inch of section, producing from the impulsive nature of the force an extension equal to that of a passive strain of 5 tons. The wonder, then, is rather that any gun stands than that many should burst. SECTION 93. A train of effects, quite analogous to those described, EXPERIMENTS ON HEAVY ORDNANCE. 187 are brought into operation in very quick firing, whether with hot or cold shot, when the interior of the gun, continually receiving fresh accessions of heat from the rapidly succeeding flashes of powder, is not given time to transmit it by conduction through its metal to the exterior. The limit of the heat that could be conceived communicated from one dis- charge to the gun, would be the whole of that generated by the igni- tion of the charge. Assuming the formula for gunpowder to be K O, NO5+S-I-C3, its atomic weight will be 135, and one part by weight will include 0.1333 of carbon. Now, Andrews (Keports Brit. Assoc., 1849,) found that one part of carbon evolves as much heat in burning as will raise an equal weight of water 7900 Cent. Hence, neglecting the sul- phur as not oxidized in combustion, the heat generated by the firing of any charge of powder is sufficient to raise the temperature of an equal weight of water 7900 x 0.1333=1053 Cent.=1895.4 Fahrenheit, or to boil about nine times its own weight of water, or to heat about nine- teen times (18.945 strictly) its weight 100 Fahrenheit. SECTION 95. In this case (that of heating by quick firing) the interior expansion is not almost limited, as in the former, to a ring in the imme- diate neighborhood of the shot, but extends to the whole length of the chase or bore, so that the whqje gun becomes lengthened by the " end on" strain of its expanded interior. THE MECHANICAL EQUIVALENT FOB HEAT. Extracts from u Sketch of Thermodynamics? by P. Gr. Tait, M.A. It is very remarkable that from the series of experiments agreeing well with one another, which were made with this simple apparatus, Joule deduced as the dynamical equivalent of heat (that is, of the heat required to raise the temperature of a pound of water 1 F.) 770 foot- pounds, differing by only about a quarter per cent, from the results of his subsequent and far more elaborate determinations. The close agree- ment of the results of successive trials was quite sufficient to justify him in publishing this, as in all probability a very close approximation to the desired value of the equivalent. (It is curious that the mean of the valves deduced from Eumford's and Colding's experiments, the two legitimate ones whose publication preceded that of this result of Joule's, differs from it by only about 2J per cent.) 36. Before leaving this part of our subject it may be desirable to com- plete the enumeration of the results of Joule's direct experiments for the determination of the mechanical equivalent, as they are certainly supe- rior in accuracy to those of any other experimenter. Kepeatiug in 1845 and 1847 his experiments on the friction of water, but now by means of a horizontal paddle, turned by the descent of known weights, he obtained results gradually converging, as in each successive set of experiments extraneous causes of error were more completely avoided or allowed for. The value of the equivalent deduced in 1847 from a great number of experiments with water was 781.5 foot-pounds, and with sperm oil, 782.1. In the paper of 1845, we find his first specu lations as to the absolute zero of temperature, or the temperature of a body absolutely deprived of heat. The most interesting of his results are, that the absolute zero of temperature is 480 Fahr. below the freez- ing point of water, arid that a pound of water at 60 Fahr. possesses, in virtue of its heat, mechanical energy to the enormous amount of at least 415,000 foot-pounds. Changes have since been shown to be necessary in 188 EXPERIMENTS ON HEAVY ORDNANCE. these numbers, but they are comparatively unimportant. And it must be regarded as one of the most extraordinary results of physical science, that a pound of water at ordinary temperatures contains heat capable (if it could be applied) of raising it to a height of at least 80 miles. 37. Finally, in 1849, Joule published the results of his latest and most elaborate experiments, of which, after what has been already said, the results only need be given : From friction of water 772.692 foot-pounds. " " mercury 774.083 " cast-iron 774.987 " The conclusion of this valuable paper, after all allowance is made for slight but inevitable losses of energy, by sound and other vibrations, are thus given : 1st. The quantity of heat producedby the friction of bodies, whether solid or liquid, is always proportional to the quantity of icorTc expended. 2d. The quantity of heat capable of increasing the temperature of a pound of water (weighed in vacuo, and taken at between 55 and 60 ) by 1 Fahr., requires for its evolution the expenditure of a mechanical force represented by the fall of 772 pounds through the space of one foot. It is only necessary to observe, that the determination is for the value of gravity at Manchester, and must of course be diminished for higher, and increased for lower latitudes, according to the well-known law. 38. As no one has yet pretended to rival in accuracy the experiments of Joule above mentioned, and as his celebrated result of 1843, so very close to the truth, preceded all other recent sound attempts to determine the mechanical equivalent of heat, the results of direct methods since employed by other observers may be passed over with the remark, that they agree more or less perfectly with those of Joule. * # # # * # * 87. The unit for measurement of work usually employed by British engineers is the foot-pound; and though this varies in amount from one locality to another, it is in such general use and so convenient when absolute accuracy is not required that it will be employed throughout. It is the amount of work required to raise a pound a foot high. It is evident that to raise any mass to a given height the amount of work required is proportional to the number of pounds in the mass, and also to the number of feet through which it is to be raised. Thus, to raise a hundred weight a furlong high requires the same expenditure of work (73.920 foot-pounds) as to raise a stone-weight a mile high, or a pound 14 miles. And the potential energy of the raised mass, or the work which can be got out of it in virtue of its position, is precisely equivalent to the work which has been employed in raising it. TIME AND TENSIONS EFFECT OF TIME ON TENSIONS. Extracts from " Experiments on Metals for Cannon and Cannon Powder." Rodman, p. 28. Report of Captain Rodman, January 30, 1867. These results appear to leave no doubt as to the superiority of the hollow over the solid cast guns, while new; what effect time may have upon them can only be ascertained by experiments ; but it is difficult to understand how time could ever so far change their relative endurance as to cause the solid cast guns to surpass those cast hollow in this quality. ******* The only effect of time is supposed to be to relieve the metal from the strain to which it had been subjected in cooling, it not being sup- posed to effect any change in its actual character. EXPERIMENTS ON HEAVY ORDNANCE. 189 It would, therefore, appear to be reasonable and safe to predict that the utmost effect which time could produce would be to bring their endurance to an equality ; and should this be found to be the case, which is not prob- able, it would still leave the hollow cast gun superior to the other 5 as it is believed that it may be mounted for service as soon as finished, and relied on for at least 150 rounds, for 10-inch guns ; while the solid cast gun cannot be relied on for a single fire when new ; nor can any limits, below which it shall be safe, be with any degree of certainty assigned to it after any lapse of time. The cause of this difference is believed to be that the hollow cast gun is so far relieved from strain in cooling as to remove the possibility of its ever being injured in that process ; and the more perfect this relief, the more nearly will the endurance of the new gun approach that of the same gun after any lapse of time. While in the new solid cast gun it is certain that the interior is under a very heavy strain, which requires time for its removal ; and there is no certainty that this strain has not been sufficiently great to produce either actual cracks, or such a degree of molecular separation in the interior portions of the gun as no lapse of time will remedy. That good solid cast guns may be made is not doubted, for they have been made ; but that it is possible to distinguish before the trial the safe from the unsafe gun is not believed. Report on the effect of time in removing strains caused by the unequal cooling of heavy iron castings. PITTSBURGH October 12, 1852. SIR : Since my report of the 24th of January last, on the manufacture and extreme proof of 8-inch and 10-inch colunibiads, Major Bell has com- pleted the extreme proof of two 8-inch coluuibiads, cast in 1846. The extraordinary endurance of these two guns induces me to submit some further considerations upon the subject. The mechanical tests and the endurance in firing of the three 8-inch columbiads are as follows : Density. Tenacity. No. of fires endured. Cast and proved in 1851 7 287 37 811 72 Cast in 1846 and proved in 1852 7.247 29, 423 2,582 Cast and proved in 1852 .. . . 7. 220 22, 989 800 The form, dimensions, weight, method of casting and cooling, and the manner of proving, were the same in all. It will be seen that the gun made of the strongest iron, with a short interval of time between its manufacture and proof, endured the smallest number of fires $ and that those made of weaker iron, but proved long after they were cast, endured the greatest number of fires. This remarkable feature in these trials suggests an inquiry as to the cause of such anomalous results. In the former report, made in January last, the character and the effects of the strains which occur in the cooling of iron, when cast in large masses, are stated and discussed. But now it appears, from the results obtained in the trials since made, that there is another question to be considered ; that is, longevity of such strains, or the length of time during which a body will remain under a strain, without a renewal of the strain- ing force. 190 EXPERIMENTS ON HEAVY ORDNANCE. It is assumed that any casting, or any other solid body will, if con- stantly strained for a long time, adapt itself, in part at least, to its strained position, and lose its power of voluntary restoration to its original posi- tion. Suppose, for example, that a proof bar of cast iron be strained in the testing machine until its deflection is about two-thirds or three-fourths of that which it will endure \vithout breaking, or ulitil the deflection nearly reaches the point at which incipient molecular separation occurs, and that the pressure be then removed ; it will be found that the bar has acquired a small measure only of permanent set. But if pressure is not removed, or if removed it be again applied, and be continued a long time, it will be found that the bar has acquired a permanent set, nearly equal to its deflection, and that its power of restoring itself to its original position has been almost entirely lost. Its particles, it would seem, have adjusted themselves to their new and constrained position, and become free, or nearly so. It appears that they resist constraint and retain the power of self-restoration for a short time only ; but if the restraint be long continued, they gradually conform themselves to it, and become passive and acquiescent. A bar which has thus been made to acquire a large permanent set, it is believed, has lost but a small portion of its power to endure renewed strains. It may be again pressed with a similar force, and acquire an additional deflection and permanent set, nearly or quite equal to that which had before been imparted to it. By repeating this process at long intervals of time, the permanent set of a bar may be extended much beyond the deflection which it was capable of enduring when it was first strained. Familiar examples of the facility with which bodies conform to con- strained positions may be observed in the hoops of common barrels, whether consisting of wood or of iron. The hoops, when first bent around the barrel, lose but a small part of their power of restoration, but when united at their ends, and driven firmly down upon the barrel, they soon lose most of their active power of restoration, become passive, and acquire a permanent set, conforming nearly to the circumference 011 which they were strained. When they have thus acquired this permanent set, they may be further bent upon smaller circles, until reduced to a curve which, if attempted at first, would have broken them, while the strength of the hoop will remain unimpaired. If solid bodies do thus relieve themselves from strains produced by the application of an external force, why may not a gun casting relieve itself in like manner from the strains caused by unequal cooling ? The strain produced in cannon by unequal cooling, as described in the preceding reports, is one of compression on the exterior circumference, and of elongation on the circumference of the bore. It may be likened to the strain which would exist in a hollow cylinder, if the latter be cut through its thickness in one of its elements, and the fissure be afterwards enlarged by a mechanical force acting against the surfaces of the fissure. A strain thus produced would obviously stretch the interior surface of the cylinder, and compress its exterior surface. Now, if we suppose a strain of this kind to be so far extended as to approach nearly to the point at which incipient molecular separation occurs, any considerable addition of a central force, of any kind, will evidently produce rupture. This is, I believe, the condition of cannon when under a strain caused by unequal cooling. And as the force of fired gunpowder acts in the same direction, a few fires, if made soon after casting the cannon, will be suffi- cient to burst it. But if the same cannon be allowed a sufficient time EXPERIMENTS ON HEAVY ORDNANCE. 191 between the casting and proving', to free itself from strain, it will endure a number of fires proportioned to the tenacity of the metal from which it is made. What length of time may be required to free a gun from strain can be ascertained only by experiment ; but it will doubtless be found to be proportioned to the hardness and tenacity of the iron, and to the bulk of the gun. Hard, strong iron, contracts most, and conse- quently is most strained, and will require the longest time to relieve itself. On this hypothesis, the results obtained in the extreme proofs given in the preceding tables may be rationally accounted for. If we refer to the 8-inch columbiads cast solid, we find that the one cast in 1851, and proved in 30 days after it was cast, or say in about three weeks after it had cooled, we find that with a tenacity of 37,811, it only endured 72 fires ; while of the two columbiads of the same model, cast in 1846 and proved in 1852, more than six years afterwards, one of them, with a tenacity of 22,989, endured 800 fires, and the other, with a tenacity of 29,423, endured 2,582 fires, and remains unbroken. Results so remarkable cannot be accounted for in any other way, that I can conceive, than on the assumed hypothesis before mentioned, viz : that large iron castings, when cooled from the exterior, are unavoidably strained in cooling, and that such strains, if within the limits of incipi- ent rupture, are removed by time, leaving the casting free. The method of cooling from the interior, devised by Lieutenant Eod- man, tends to prevent injurious strains in cooling ; and if the method be sufficiently extended on this principle, a strain in the opposite direction may be produced. The strain, in this case, would be one of compression on the surface of the bore, and of elongation on the circumference of the gun ; and the tendency of such a strain would be to prolong the endur- ance of the gun beyond the proportion of fires due to the tenacity of its metal. This theory of the effect produced by time in removing strains caused by the unequal cooling of iron castings, appear to be so well sustained by the facts exhibited in the experiments cited, and its bearing upon the subject of casting heavy cannon appears to be so important, that I have thought it my duty to state it, and to submit it to the department. Eespectfully, your obedient servant, W. WADE. Colonel H. K. CRAIG. THE RODMAN PRESSURE INSTRUMENT. Extracts from " Experiments on Metals for Cannon and Cannon Powder." Rodman, p. 197. Table showing the velocity of shot, in feet per second, and pressure of gas per square inch, in pounds, due to equal columns of powder behind equal columns of metal when fired in guns of different diameter of bore, each result being a mean of lOJires. "o . o o Pressure at different distances from bottom of bore. I ll 11 1 .5" j9 '* *> ** V At bottom. At 14 in. At 28 in. At 42 in.' At 56 in. At 70 in. At 84 in. Q ? F P |> In. ids. Lbs. 7 .07 5.13 74.44 904 36, 420 15, 850 8,370 6,470 6,850 8, 050 6,720 9 .09 8.48 124. 42 883 67, 100 21, 100 17, 759 14, 900 29, 475 20, 970 22, 825 11 .11 12.67 18G. 03 927 86, 750 29, 300 27, 800 22, 420 28, 400 33, 850 25, 050 192 EXPERIMENTS ON HEAVY OKDNANCE. The points most worthy of note in these results are the very marked increase in pressure of gas as the diameter of bore increases ; and that the indications of pressure are greater at 56 inches, 70 inches, and 84 inches than at 42 inches, especially in the 9-inch and 11-inch guns. The cause of the difference in pressure developed in these guns of dif- ferent diameters of bores is believed to be mainly due to the greater heat developed by the combustion of the larger mass of powder in the large than in the smaller calibre, and perhaps, also, to the different products of combustion formed under this increased temperature and pressure, and partly to the greater cooling surface in proportion to the weight of charge in the small than in the larger calibre. UNCERTAINTIES AND INCONGRUITIES CONNECTED WITH THE FABRI- CATION OF GUNS. Extracts from report of Captain J. T. Rodman experiments on metals for cannon and cannon powder. This investigation is ordered as a probable explanation of the differ- ence in endurance of guns cast and cooled in the same manner, made from iron of the same qualities, treated in nearly the same manner, and differing but slightly in quality in the guns themselves. Probability, however, is not Jcnowledge^ but it is the most that can now be offered as well upon this as upon many other points of equal importance. We do not know, for example, what qualities of iron are necessary to make the best gun ; nor, if we did, do we know how, from any of its ores, constantly to produce iron which shall possess those qualities. We do not know whether guns should be cast hollow or solid, nor the proper rate of cooling for either mode of casting. We do not know the best exterior model for guns, nor whether those of large calibre should be made with or without chambers. We do not knoie the effects of time upon the endurance of guns whether they are better when new, or after they have lain unused for any given length of time. We do not know the maximum statical pressure due to a given weight of powder and shot, nor how much the rate of combustion of the charge, or the rate of application of the force, causes the bursting tendency to exceed that due to the statical pressure. We do not know the difference in endurance due to a given difference in bursting tendency at each discharge, nor what weight of projectile is equivalent in bursting tendency to a given weight of powder, nor the difference in endurance due to a given difference in thickness of metal. We do not know the difference in bursting tendency due to a given difference in temperature of the same charge of powder at the moment of ignition. Nor do we know the proper constitution of charge in order to produce a given velocity of projectile with the minimum bursting tendency of the gun. * * * * * There is no other known cause for any considerable difference, yet we cannot with certainty announce this as the only cause, for a single result is not conclusive ; and differences, almost if not quite as great, in the endurance of solid-cast guns, have been found to exist, without any known cause. # * * * # * The cascabel dropped off the solid-cast gun at the 761st fire, and a number of cracks were discovered in the face of the muzzle after the EXPEKIMENTS ON HEAVY ORDNANCE. 193 1209th fire, some extending back three or four inches. These cracks have not since increased, and are believed to be due to some accidental cause, rather than to the regular deterioration of the gun from firing. The cascabel dropped oif the hollow-cast gun at the 1,379th fire. All the trunnions of both guns are slightly cracked at the junctions of the guns and rimbases, the left trunnion of the hollow gun apparently the worst. There is a very marked difference in the interior appearance of the two guns, the bore of the solid-cast gun being greatly more deteriorated than that of the hollow-cast gun. There are three cracks radiating from the interior of the first, and one from that of the second vent, in the solid gun. Those from the first vent are from two to three inches long, running in an almost transverse direction around towards the first vent. There are no cracks perceptible in the hollow gun. Extract from the report ofi tlie Joint Committee on the Conduct of the War. It is, therefore, of the highest importance to obtain, if possible, some kind of heavy ordnance which shall not be liable to these objections. The entire efficiency of an iron-clad vessel, costing the government hun- dreds of thousands of dollars, may depend almost entirely upon the character of the guns with which she is armed. In the words of the Assistant Secretary of the Navy, "you might lose a battle by going into action with a gun around which stood 25 men entertaining the idea all the, time that it might burst." Considering the great cost of our iron- clad vessels, and the importance of the results to be attained, by render- ing them as secure and efficacious as possible, a few thousand dollars more of expense would seem to be of but little moment, if it affords the only means of reaching the end desired. The disastrous results attending the bursting of a gun can be, to a greater extent, guarded against upon land than at sea. In the latter case the loss of the vessel, with all on board, may be the consequence, while the demoralization of the crews of the other vessels similarly armed may lead to results almost, if not quite, as disastrous. But, upon both land and sea, it is of the utmost importance to obtain heavy ordnance of the most reliable character. '''"# * * * * The bursting of these guns is generally attributed to the explosion of shells, prematurely, within the bore of the gun. The opinion of Mr. Parrott, in regard to the cause or causes of premature explosion of the shells, is as follows : It has been a matter of much concern with me, and I would rather not make a gun than have any accident occur. I ascribe the difficulty to the friction of the powder in the shell itself. At first it was natural enough to ascribe the difficulty to bad shells, bad castings, bad fuzes, &c. ; but, upon full trial, it appears above all question that the diffi- culty arises from the powder exploding in the shell within the gun by friction, caused by the striking of the powder against the inside of the shell. A 300-pounder shell is 10 inches in diameter; a round shell of that diameter holds about three pounds of powder. My 300- pounder shell holds about 17 pounds of powder. Now, when you fire a gun, and strike the butt of a shell suddenly with the immense force of the cha r ge, there is a reaction of the pow- der within the shell against the bottom of the shell, and if there is any roughness so as to cause friction at the bottom, the powder will be exploded in the shell while it is within the- gun., Thinking that to be the case, I have for a long time been endeavoring to coat the inside of the shell with varnish or lacker, and I am able to do it with entire success. A great many people were skeptical about it, and precautions have not been taken, in regard to it, as quickly as they might have been. I now melt together rosin, tallow and brown soap, forming a thin liquid mixture, and pour it into my shells and pour it out again, leaving a coating on the inside which covers over the rough iron, and when that is done I find the shells can be fired without premature explosion. Rep. No. 266 13 194 EXPEKIMENTS ON HEAVY ORDNANCE. Some two months ago Captain Temple, one of the officers of this very fleet of Porter's, came to the foundry and became aware of this fact. He had two 100-pounders on board his vessel ; when he got back he found that his shells had no such coating, and he immediately set to work and lined them with asphaltum, &c. He fired his guns 50 or 60 times each during the engagement, and not a single shell exploded prematurely in his guns ; while in some of the other vessels around him shells were exploded prematurely, and thrown out of the guns in fragments. That is so stated in a letter of his which I saw yesterday. Be the cause or causes what they may be, the fact is that these guns do burst while in action, with very disastrous results. Extract from tlie testimony of Brigadier General George D. Ramsay before the Joint Committee on the Conduct of the War, p. 12. Q. I cannot myself see why it would not be easy to take a 100-pounder Parrott gun, for instance, and a 100- pounder Kodm an, and subject them to certain tests of powder and ball, and ascertain which is really the most energetic gun, and which will stand the most charges. A. There would be no difficulty about it, aH things equal. Some of the Parrott guns have burst before Charleston. This, however, is ascri bed 'to various causes, one of which is the frequent explosion of the shell in the gun, and the introduction of sand into the bore. Q. That would be no evidence of the power and strength of the gun when properly fired. A. No, sir. RATIO OF GOOD AND BAD GUNS. Extracts from the report of Captain J. T. Rodman. Experiments on metals for cannon and cannon powder. Out of seven solid-cast experimental columbiads, one gun only proved to be good. Out of six hollow-cast columbiads, three were good, having been fired 1,500, 1,600, and 2,452 rounds respectively, and neither gun broken. It is not deemed out of place here, in order to show the necessity of further investigations into the properties of cast iron in its application to the manufacture of cannon, to notice some facts in the history of gun- founding in the country since 1849. The very low endurance of the first pair (8-inch) of experimental guns which were cast in that year was attributed to the inferior quality of the iron of which they were made. Two years were spent in searching after a better quality of iron, which was undoubtedly found, and in 1851 another pair of 8-inch guns was cast. The iron in this pair of guns has a tenacity of near 38,000 pounds, while that of the iron in the first pair was only between 27,000 and 28,000 pounds. The solid-cast gun of the first pair burst at the 85th fire, and that of the second pair at the 73d fire, the superior iron giving the inferior solid- cast gun. These results did not, however, destroy confidence in strong iron for solid-cast guns, and the first pair of 10-inch guns was made from the same lot of iron, and, with a tenacity of iron of 37,000 pounds, the solid-cast gun burst at the 20th fire. This result weakened confidence in very strong iron, and the tenacity was reduced. In 1857, after guns of good tenacity had failed at the Fort Pitt, South Boston, and West Point foundries, four out of seven guns offered for inspection at the last-named foundry having burst in the proof, Mr. Parrott, proprietor of the West Point foundry, one of our most experienced EXPERIMENTS ON HEAVY ORDNANCE. 195 gun-founders, cast his trial contract guns of iron, having a tenacity of 30,000 .to 32,000 pounds. One of these guns has endured 1,000 service charges of 14 pounds powder, (800 rounds with shells and 200 with shot.) The iron selected at that foundry, and from which the last five experi- mental guns have been made, was of the same quality, and in the same proportions, as in the guns last above referred to. In 1858, after the failure, at the 169th fire, of the West Point experi- mental gun made from this iron, Mr. Parrott condemned it as being too high for heavy guns. From this rejected iron was made the last pair, Nos. 362 and 363, of trial 10-inch guns, at the Fort Pitt foundry, which have been fired 2,452 rounds each, the least charges fired being 14 pounds powder and one solid shot, and neither gun broke. These guns have since been fired 1,000 rounds each, with 18 pounds of powder, and solid shot, and neither gun got broken. It should also be borne in mind that the proprietors of the West Point foundry have control of the smelting furnace at which their gun-iron is made; they ought, consequently, to have a more perfect knowledge of the qualities and properties of their iron than those founders who are dependent upon the market for their iron. These facts to my mind are conclusive as to the fact that we are at present far from possessing a practical knowledge of the properties of cast iron in its application to gun-founding; and it is too much to expect of private enterprise to take up and prosecute so intricate and expensive an inquiry. Extract from the testimony of Brigadier General George D. Ramsay before the Joint Committee on the Conduct of the War. Q. You have stated the tests to which these guns were subjected. What reason is there for believing that these tests are satisfactory; what reason have you for placing confidence in them ? A. The reliability of the experiments, as shown by the endurance of the guns. Q. You think they are satisfactory? A. Yes, sir; every effort has been made to render them so. ****** Q. You consider the Eodman gun the best gun now in use? A. Yes, so far as guns made entirely of cast iron are concerned. Q. What tests have been applied to the Rodman gun I A. First, there is the preliminary test of ores, which embrace all the scientific investigations deemed necessary. Castings from the ores selected are tested for density and tenacity. Experiments have estab- lished standards below which guns are not received. Then comes the powder proof. The only proof to which guns were formerly subjected was by using excessive charges ; but this was found to be objectionable, and not reliable, as there was no assurance that after all the trials with heavy charges the gun would not, as often happened, burst with the ordinary service charge. Confidence was greatly impaired, and many serious accidents from bursting ensued. I refer to guns cast solid. The theory of Captain Eodman being undoubtedly correct, experiments were made in order to verify or refute it in a practical manner. Several sets of cannon of the same form and calibre were cast, part in the ordinary method of casting solid and cooling from the exterior, and the same number on Rodman's plan. These were fired alternately, alongside of each other, with charges of powder and ball of the same weight and kind, and continued until one or the other class of cannon gave way 196 EXPEKIMENTS ON HEAVY ORDNANCE. under the repeated firing. The result of these trials on several sets of cannon showed conclusively a far greater endurance for the Rodman gun, more than 300 per cent, greater than those cast in the ordinary way ; that is to say, we could rely on getting as much firing from one Rodman gun as from three guns cast solid in the usual way. Besides this greater durability, the Rodman gun possesses the greater advan- tage of reliability in use ; that is to say, being served without danger to the men standing by it from bursting of the piece. Q. The powder test is the test by powder and ball the service charge ? A. Yes, sir ; and when a new kind of gun or ore is introduced, the trial is 1,000 pounds. MODELS OF aims. Extract from the testimony of Brigadier General George D. Ramsay before the Joint Committee on the Conduct of the War, p. 10. Q. I understand you that this Rodman gun was shaped after the experiments of Colonel Boinford, to ascertain where the greatest strain would come? A. Yes, sir ; but whether Captain Rodman had these in view when he investigated the subject, (which investigation will be found in a work of high reputation on experiments on metals for cannon and cannon powder, by Captain Rodman,) I am not prepared to say. As to the shape of the gun, Commander Dahlgren, in a letter to Secretary Floyd, accused Captain Rodman of plagiarism, on the completion of his (Rod- man's) 15-inch, and which led to a correspondence between these officers. Rodman's gun conforms more in exterior shape to the columbiad than the Dahlgren. Q. Does the advantage of the Rodman plan consist in the fact that the gun cast hollow with a stream of cold water poured through the inside ? A. Yes, as regards the casting. But the Rodman gun embraces more than this the exterior form. Formerly guns were in their exterior form a series of sections of straight lines, called reinforce, somewhat analogous to the joints of a telescope when drawn out, but the Rodman gun (which the witness illustrated by a diagram on a piece of paper) gives a curved section. The thickness at the seat of the charge in cast- iron guns is a little more than the diameter of bore, gradually tapering to the muzzle. Some twenty years ago the late Colonel Boinford insti- tuted a series of interesting and original experiments to determine the expansive force with which fired gunpowder acts at different points along the bore of the gun and with the view of ascertaining the requisite curve of resistance; that is to say, at what points the metal received the greatest strain, and consequently where the greatest thickness was necessary. From these experiments the columbiad a gun so called originated, and to which may be traced the French Paixhan gun. The columbiads were originally made with chambers, and are now used for shot and shell. Colonel Bomford did not pursue his investigation beyond determining the above facts. These experiments satisfactorily show that the greatest force of the charge is exerted on the part of the gun which is situated in rear of the centre of the ball, and the force diminishes rapidly as the ball moves forward from its orignial position. Q. When was this investigation I A. About 1843. It is understood that a French ofiicer, General Paix- han, when on a visit to this country, was made acquainted with the exper- EXPERIMENTS ON HEAVY ORDNANCE. 197 iments of Colonel Bomford, and on returning home he introduced a similar gun into the French service, the Paixhan gun, as a shell gun. Q. Then I understand you the principle is an old one ? A. Not the principle of cooling from the interior. Q. The shape of the gun? A. This shape of gun is yet somewhat a matter of contention. It matters not what the shape of the gun is, within certain limits, if cast on correct principles. Q. Describe the Dahlgren gun and the Bodman gun, and its advantage over the Rodman gun or coluinbiad. A. The Dahlgren gun is cast solid and cooled from the exterior. The diameter of the rough casting at the chase is much greater than that of the finished gun ; the surplus metal is turned off into the lathe. The Eodman gun and the columbiads are cast hollow and cooled from the interior. The. advantages of one form of gun over another is an open question, and it matters not, within certain limits, if the gun is cast on correct principles, such as Rodman's, as before stated. But as to the advantages of casting very heavy guns on Rodman's plan, the Navy Bureau of Ordnance has shown its confidence in the method of having them so cast at the present time. Q. Has either one of those guns any advantage over the other in actual use or practice ? A. In practice the Rodman gun cast hollow, in my opinion, must have decided advantages as to endurance; as to range, this will depend upon the circumstances under which they are fired. EXPERIMENTS AT SHOEBTJRYNESS. From the London Times. v The late trials of the 15-inch American gun and the English rifled mountain gun for the Abyssinian expedition have been full of interest. The heaviest smooth-bore and the lightest rifled gun in England were fired side by side. The experiments with the American gun have not led to any desire on the part of English artillerists to adopt the system, but we hasten to admit that the huge Rodman is a magnificent gun of its kind, and shows a process in the manufacture of cast iron which does the gallant officer who has devoted himself to that branch of artil- lery science infinite credit. It is curious that both American and Eng- lish pieces of heavy ordnance are showing signs of far greater endurance than was foretold by their respective backers. When first the Rodman guns were issued for service, 60 pounds of their service powder, what- ever it may be called, was considered the highest charge that could be fired from it with safety, and that only a few rounds. The English 9-inch gun in the same manner was allowed only 150 rounds, with its battering charge, and 400 rounds were named as constituting its probable life if the whole 150 battering charges were to be used in it. Since then the Rodman has been fired at Fortress Monroe with 100 pounds of powder, and a like trial at Shoeburyness has shown that the feat can be repeated, but we have yet to learn how often with the same gun. One of our 9-inch rifled guns has stood 1,043 rounds, 680 of which were with battery charges, some as high as 50 pounds, and the gun, though much eaten away in the interior, is still capable of offence. Two other 9-iuch guns have been fired 500 rounds each with battering charges, and are still in excellent condition. We do not consider our 13-inch rifled gun a success, but it was fired several times with 100 pounds of strong English powder without bursting, and when two shot struck near each other the second 198 EXPERIMENTS ON HEAVY ORDNANCE. passed through the Hercules target, which is probably the stroDgest yet constructed. It is very necessary in the comparison of different artillery systems to distinguish between the many different questions involved. In the present almost international competition the principal questions are: 1st. Backing v. punching; 2d. Comparative penetration; 3d. Killed v. smooth-bore guns; 4th. The material of which the, national ordnance is to be made. The difference between gunpowder is hardly a question, because, though ours is stronger than the American, we do not claim any advantage in that respect, but rather the contrary, because quick- burning powder is too severe on the gun. The name by which the Ameri- can powder used in the late experiments is known to the United States authorities is hardly settled yet, for there are many gunpowders in their list, and though the present sample is not the largest mammoth powder such as was meant when we were told that 50 pounds of it only equalled in strength 35 pounds of No. 7 cannon powder, neither does it appear to correspond with the size of grain laid down for this latter. It is perhaps something between the two, and its name is still uncertain. "American service powder" was the name used in contracting for it, and "American service powder" it is, of a strength one-sixth less than English powder for heavy guns, whatever may be its exact title. No one at all acquainted with the subject can deny, in the face of all experiments made throughout the world, that elongated shot are better calculated for penetration than round ones, nor did the Americans deny this when they first produced their heavy guns. They said that they did not wish to perforate or "punch" targets, but to smash them to pieces or "rack" them. Their ships were protected with "laminated" armor, by which is meant armor composed of several one-inch plates laid upon each other and plated together. This is a kind of structure easily shattered, and even far more vulnerable to punching guns than solid plates, or a lesser number of thicker plates. English constructors saw no difficulty in building ships that could not be -racked by guns of the power set forth in American publications, and the result of the late experiments has proved the truth of the assertion. It was only at close quarters and with charges of 60 pounds too much for continued firing, according to their own authorities that officers were allowed to attempt to penetrate a strong iron-clad ship'. The contest between the advocates of racking and punching was hot, and we were unprepared for the vexa- tion exhibited throughout the Unites States when it was found that their cast-iron and even our steel shot fired from their gun failed to penetrate the target. If penetration and not racking merely be now claimed for their guns, the only points to be assured of are these. Is the average strength of a 15-inch gun sufficient to enable their naval and military authorities to authorize the employment of 100-pound charges, and, if so, will the projectiles which they use hold together long enough to get through when they strike? A steel shot with 1,500 feet of velocity will penetrate the 8-inch plate and Warrior backing. A cast-iron shot mayor may not, according to the excellence of its material. Probably, but not certainly, it will penetrate. Certainly neither of them will perforate the Hercules. It is very instructive to look back a little and see how short a time has elapsed since the object of iron-clads was supposed to be the keep- ing out of, shells. Mr. Whitworth T s achievement when he fired a steel shell through the Warrior target rang through Europe, and now chilled shells with oval heads have a power of penetration superior to that of shot. The 9-inch gun sends its shells through the 8-iuch target, and we EXPERIMENTS ON HEAVY ORDNANCE. 199 know that no round shells from the 15-inch Rodman have a chance of piercing it, whatever may be the success of their shot. And then, be it remembered, this 15-inch gun weighs seven tons and a quarter more than the English 9 inch. Many honest inquirers who are watching the results of the trials may say, " There is something very odd about this matter. What is the virtue of the English gun that it can send its lighter projectiles with lighter charges through a target that resists a far greater expenditure of ammu- nition on the part of the American gun? Is it quite fair not to use chilled shot or shells which are so cheap and strong in both cases?" It is fair, and, indeed, it would be very unfair to the American gun to put chilled projectiles into it, and estimate its force by their effect. One chilled, or rather white iron shot, was fired from it at the 8-inch target, and did least damage of the three hurled against it on the same day, as would have been predicted beforehand by all who understand this not very abstruse question. White iron projectiles are very brittle, and are of little use unless they have sharp points and are driven point foremost, which can only be done if the gun is rifled. The range at 32 degrees elevation and with 100 pounds charge was 7,680 yards, the initial velocity about 1,538 feet a second; 1,600 feet a second is a common velocity for smooth-bores, and much higher speed has jDeen attained in the wrought-iron guns constructed some years ago for the navy. The Rodman gun is probably too short to burn all the powder before the shot leaves the muzzle, and a further increase of charge would not give proportionate velocity. Sixty pounds gives 1,170 feet per second; 100 pounds only increases it to 1,538 feet; quite enough, however, to force an entrance into any of our ships at present afloat, if the range is short, and if the gun is fired at right angles to the side of the ship. The least angle will affect your round shot more than the pointed one, because the former will glance, while the latter digs in its point and then turns at right angles to the target. This was well shown on Thursday last, when an 8-inch shell from a converted Palliser gun pierced the Warrior target at an angle of about 26 degrees, the weight of the shell being 180 pounds, that of the charge 22 pounds. We hope that many interesting experiments will yet be made with the American gun, and we sincerely congratulate Major Rodman on the excellence of his cast-iron, while we still adhere by preference to our own material, which is still stronger, especially for rifled guns, because grooves in a gun cast on Rodman's method would vitally affect its strongest part, the interior. Let us pay every respect to a very formidable weapon, but we can do so without crying down our own lighter but even more destructive ordnance. We cannot admit 100 pounds to be a service charge till the American War Office gives us a right to do so, and if the 15 inch gun is to be compared with our 9-inch, and exceptional charges are to be burnt in the former, we can hardly be denied the right to put a little extra powder into the latter. The 15-inch, with its service-batter- ing charge, fails to penetrate the target which is pierced by the 9-inch with such a charge that several hundred rounds can be fired without destroying the gun. From the roar of the Rodman to the tiny ringing voice of the mountain gun is a great downward jump, but the little steel piece is soon to do its duty in actual war, unless wise and peaceful counsels prevail at last in Abyssinia. Steel, while treacherous in large masses, from the difficulty of casting and working it equally, is a perfect though rather expensive material for small guns, and has been wisely chosen for mountain service. The carriage is also of steel, except the wheels, and nothing could be simpler than its general construction. It stood the force of recoil very 200 EXPERIMENTS ON HEAVY ORDNANCE. well generally, though the wheels suffered a little from the recoil of the piece when fired at high angles of elevation. This niite of a gun, which a man might easily carry in his arms, for it weighs only 150 pounds, sent its pretty little 7-pound projectile 2,944 yards, or more than a mile and two-thirds, with a charge of 6 ounces of powder and an elevation of 32 degrees. Such long range work is not, however, likely to be required of it, but rather shrapnel practice at ranges up to 1,000 yards or less. At 500, 520, and 540 yards more than half the bullets in the shrapnel shell struck a target representing a column of men. With half an ounce of powder and the same elevation the projectile ranged 478 yards. The recoil, which was very lively when full charges were used, was brought under control by hobbling the carriage, a small rope being fixed from the point of the trail to one of the wheel spokes. The so-called 64-pounder gun, converted on Palliser's principle, proved its value by sending its shells through the Warrior plates, breaking once out of three rounds through the skin and setting the wooden backing on fire. The charge was 1C pounds, range 500 yards. The 8-inch converted gun did even more work at 70 yards range, at an angle of about 26 degrees to the face of the target. The first round at 30 degrees angle set the target on fire, the second at nearly 26 degrees passed through all, bursting just as it cleared the inner skin. Here are three instances of the value of rifled guns. Shell-fire either penetrates the target opposed to these comparatively light pieces, or sets the backing in flames. Let us once more put the state of the case before our readers. The smooth-bored gun, with its service-battering charge, and an expensive steel shot, fails to damage seriously a target which the rifled gun, less than tAvo-thirds the weight of its antagonist, penetrates with shells of a cheaper material. With an increased but dangerous charge the smooth- bore will probably penetrate the target with shot but never with shell. The rifled gun can be used in broadsides, the smooth -bore only in turrets. Given the same weight of rifled gun, the effect will be much greater. If the material of which the guns are made be compared, we take the actual results obtained at Charleston, and fearlessly assert the superior strength of our ordnance, for the federal rifled pieces were declared by General Gillinore to be unable to fire 500 rounds with charges of only one- tenth the weight of the projectile. Our 9-inch rifled guns outlive many more than 500 rounds with charges of about one-sixth the shot's or shell's weight. These are not theories but facts, and if any opposing facts can be urged in contradiction they are at least out of the bounds of our present experience, and we shall be glad to hear them. Such is the comparative power of the two systems of ordnance. The positive power of the Kodman with the power lately fired is as follows: With 50 pounds of powder its power is very low compared with its weight. With 100 pounds it can penetrate the sides of any ship afloat in the English navy, and the 8-inch target at 70 yards, the shot's energy being about 153 tons per inch of circumference. This supposes that the pro- jectile is of steel. Cast-iron may or may not break up according to its quality. At 700 yards it would pierce the Warrior, Lord Warden, or Bellerophon, but probably not the 8-inch target, certainly not the Her- cules or Monarch, now on the stocks. Its powers at 700 yards are much inferior to the 13-inch rifled gun with 100 pounds of English powder at the same range, the difference being about 56 foot tons per inch of circum- ference. At no range whatever would the American gun with 100 pounds charge perforate the side of the Hercules. These calculations are based upon Captain Noble's formula, (which is in use in other countries besides England, Prussia for instance,) and upon the known strength of the EXPERIMENTS ON HEAVY ORDNANCE. 201 English targets. To complete the interest of the late experiments it would be well that the select committee should try targets on the Ameri- can system and one of Krupp's heavy guns. RIFLED GUNS. Extracts from the report of the Joint Committee on the Conduct of the War. The proportion of rifle guns to those with smooth-bores used in the navy is much smaller than those used in the army. The difficulty of obtaining accuracy of fire upon a vessel in motion renders the rifled guns less efficient Avhen used at sea than when used upon land. The projectile from a smooth-bore, except within point-blank range, is fired so as to ricochet upon the water, arid it continues its flight in a straight line until it stops. The projectile from a rifled gun, when it strikes the water, ricochets at an angle from the direct line, sometimes almost at right angles, and it is therefore less reliable at long range. ******* The rifled gun of large calibre, employed almost wholly in the army and naval service, is the gun invented by Robert 0. Parrott. It is com- posed of a cast-iron cylinder with a wrought-iron jacket or band shrunk upon the breech of the gun in order to strengthen it about the seat of discharge. The cast-iron cylinder of this gun was formerly cast solid, and then bored out ; but latterly those of the largest calibre are cast upon the Eodnian principle. * * , * * * * * But the bursting of the Parrott guns of large calibre, together with the bursting of some of the cast-iron guns of large calibre, upon the vessels engaged in operations against the defences of Charleston and against Fort Fisher, has tended to weaken confidence in the durability of those guns, and would seem to show the necessity of obtaining, if possible, some other gun which can be more implicitly relied upon. It is the testimony of our officers of the navy that the bursting of one gun in a fleet tends to demoralize the crew of each vessel upon which a gun of that kind is used, whether it burst or not. And it is asserted that the loss sustained by the bursting of guns of large calibre on vessels operating against Fort Fisher was much greater than the loss sustained on the entire fleet from the fire of the enemy. ******* In view of these considerations, your committee desire to refer some- what at length to a wrought-iron gun which, to them, seems to possess those qualities ot strength, durability, and safety which are so very de- sirable. It is the invention of Horatio Ames. But few of these have yet been manufactured, yet they have successfully withstood every test that has been applied to them. Upon the 21st of August last, at the request of the inventor, the Presi- dent ordered the appointment of a board to test a gun of 7-inch calibre manufactured by Mr. Ames. ******* As the result of the examination the board report : It is the unanimous opinion of the board that Ames's wrought-iron guns possess, to a degree never before equalled by any cannon of equal weight offered to our service, the essen- tial qualities of great lateral and longitudinal strength, and great powers of endurance under heavy charges ; that they are not liable to burst explosively and without warning, even when fired under very high charges; and that they are well adapted to the wants of the service generally, but especially whenever long ranges and high velocities are required. It is also the unanimous opinion of the board that Ames's 7-inch guns, of which he has now 15 nearly finished, possess sufficient weight and strength to receive an 8-inch bore and even greater, although not heavy enough for a 10-inch bore. 202 EXPERIMENTS ON HEAVY ORDNANCE. The opinion of Mr. Fox, the Assistant Secretary of the Navy, of the Ames's gun, and of the necessity for some gun of that character, is thus stated by him in his testimony : "I think it is a fair inference, from the experience we have had with the small guns and 100-pounders which he (Mr. Ames) has made, that he has the correct principle of manufac- ture, and that guns manufactured by his method will bear any amount of charge that can be consumed in the gun. * "My opinion is that we have got to come to wrought-iron or steel guns and abandon cast iron." ********* Extracts from the testimony of Brigadier General George D. Ramsay before the Joint Committee on the Conduct of the War. It may be said of the rifled guns that we were called upon to intro- duce the rifled system in time of war, suddenly and without the facilities for practical experiment. We have no government arsenal, or conve- nient place adequate to proper trials for range, penetration, &c. There is no place that I am aware of, under our control, for extensive land range, and for that reason my predecessor recommended, at the last session of Congress, the purchase of a tract of land near New York, on the New Jersey marshes, for this purpose, and which presented an uninterrupted and secure range of several miles. We have had a good deal of practice with field and the 4 J- inch rifle guns at the Washington arsenal, but necessarily over the water, rendering the experiments unsatisfactory both as to ascertaining penetration, correctness of flight, &c., of the projectiles, and of many other elements necessary in judging of what constitutes a good rifle gun and a good projectile. Q. Then you do not give any preference to the Rodman gun over the Parrott gun, but are getting both as fast as you can f A. No preference in orders given for guns is shown. We have been and are getting both kinds as fast as we can. Unlimited orders have been given to all the founders making guns. The entire capacity of the country has been called into requisition to meet the demands of the service. Everything has been done on the part of the government, so far as I am advised. Q. What proportion of our sea and land armament is of rifled ordnance, and when were rifled guns introduced into service I A. I should have to refer to the records to answer the first part of your question ; as to the introduction of rifled ordnance, my first recol- lection of them was at the battle of Bull Run. Q. What proportion of the land ordnance is rifled, so far as you know? Q. With regard to the old guns forming a portion of the armament of the fortification, we are now rifling every gun along the seaboard. We are at this very moment rifling the guns at Portland, Portsmouth, and Boston. The 24 and 32-pounders are simply rifled ; but to the 42- pounders we are applying the wrought-iron jacket in addition upon the Parrott principle, with the Parrott increasing twist. Experiments have shown that the 24 and 32-pounders have sufficient endurance without going to the expense of banding. Q. The intention is to have all the guns rifled ? A. Yes ; the old guns, to include the 42-pounders, not the Rodmans. Some of them, the 8 and 12-inch, have been rifled for experiment. Q. Does it not weaken ordnance to some extent to rifle it ? A. Yes; to some extent; but we are enabled to make reliable rifled guns, even from those originally smooth-bore, as, for example, a third class 32-pounder gun, rifled by Captain Parrott, and fired with his own projectile, 64 pounds (double the weight of the 32-pound ball) and with EXPERIMENTS ON HEAVY ORDNANCE. 203 six pounds of powder, withstood 1,000 rounds. This gun was not banded ; its tenacity was not more than 16,000 or 20,000, the standard being about 30,000 pounds. It is doubtful whether this gun, before being rifled, would have shown greater endurance with its own proper service charge with round ball. We consider a gun a good gun that will stand 1,000 rounds. Q. At what time did these rifled guns come into use I A. We had several batteries at the first battle of Bull Eun ; and have since then furnished them, with all the rapidity that the foundries could supply them. We have taken all the smooth-bore guns out of the field, and substituted rifled guns as fast as we could get them. At the battle of Bull Eun we had a 2 T 4 ^-inch, that is, a 10-pounder battery, a 20-pounder battery, and one 30-pounder gun, which was lost. Q. Can you give us any description of what is called the Whitworth gun an English gun? A. The Whitworth gun is a wrought-iron rifled breech -loading gun. It has a hexagonal bore. It is a very ingenious and beautifully made gun. It is liable to get out of working order in its breech arrangements from the peculiar construction of the screw, which requires very perfect mechanism. This screw arrangement becomes foul by escape of gas, and it is sometimes difficult to close the breech. There are also muzzle- loading Whitworth guns. Q. And the heating of the gun by firing would effect it, I suppose? A. Of course. In the models all the breech-loading guns seem to work very well ; but when you apply the principle to large masses of metal it becomes difficult to make the parts work easily. Q. What about the Blakely gun ? A. That is made a little after the manner of the Parrott gun. I think it has a jacket of wrought iron shrunk on it, commencing at the trunnions and embracing the entire rear of the gun. BURSTING OF PARROTT GUNS. REPLY OF MR. WIARD TO MR. PAR- ROTT. From the New York Evening Post, February 2, 1865. To the Editors of the Evening Post : The letter of Mr. Parrott, in your issue of Saturday last, seems to me to be an effort to resuscitate confidence in guns and theories now ex- ploded. Mr. Parrott attributes the bursting of his guns to the prema- ture explosion of shells within the bore. Why does he not show this to be the cause by a series of experiments, by bursting shells in the bore ? I assert that he cannot burst even a 30-pounder in that manner, and that a 300-pounder can be so burst is even more improbable, except the gun has been heated inside by a succession of discharges fired as rapidly as guns must be in the excitement and hurry of hot bat- tle, where the duty of the gun is quite different from the " dress parade" practice of the proving ground, where the greatest deliberation is the rule. When large guns are fired rapidly the inner metal along the bore is expanded in all directions by the successive increments of heat from the flame of powder supplied at each discharge more rapidly than it can be dispersed throughout the whole mass of metal in the gun or radiated away from the surface of the bore ; the interior swells with exactly the force it would exhibit to resist compression, straining the outside metal to the extreme verge of its power to resist fracture. When in this state, the explosion of the charge, the premature explosion of the shell, the effort of the gun to divert the shot or shell as it recoils backward (the 204 EXPERIMENTS ON HEAVY ORDNANCE. gun being elevated) on a plane different from the plane of the axis of the bore or the direction of the shot, having the tendency to throw the shot higher than it was aimed, or to depress the muzzle of the gun, sometimes breaks the muzzle off as by the blow of a heavy sledge, the gun being in a state of initial strain, may cause the fracture. Mr. Parrott cannot account for the transverse fracture under the band by the explosion of shells in the .bore. A 15-inch Rodman gun, cast hollow, and -cooled from the interior to get initial tension, at Pittsburg, a few months since, when nearly cold and ready to be removed from the pit, split from end to end. The inner metal had been cooled by water passing through the bore, while the outside metal retained a higher temperature. The outside metal, cooled at a later time, shrunk upon the inner metal like the tire upon a wagon wheel. The cast block was about 16 feet in length, and the wall about 16 inches in thickness ; con- sequently, the area of cross section ruptured was equal to 3,172 inches. If the tensile strength of the metal was 30,000 pounds to the square inch of section, the pressure bearing upon the inner metal was about 95,000,000 of pounds on each side, or a whole tension of 190,000,000 of pounds. I frequently experiment with glass models of guns, which I have sub- jected to a water pressure of 800 pounds to the inch of surface in the bore. These are broken in many pieces by inserting a heated rod of iron smaller than the bore in such a manner as not to touch the surface. The great Mallet mortar, made of a series of rings held together by six strong bolts, was disabled by the lengthwise expansion of the rings breaking the bolts. One of Blakely's guns, made with four bolts reaching from the trun- nion ring to the cascabel, broke the bolts in the same manner.* The inner tube of the Whitworth gun, shown in General Gillmore's report, increased in length by the heat communicated to xit, and closed the vent, being shown projecting one inch.t If the bands had been fastened by screw-threads, as proposed by Professor Treadwell, and recommended by General Gillmore in his book for the bands of the Par- rott gun, it would not be an improvement ; the bands would part trans- versely as did the breech of a 300-pounder Armstrong gun, in which the breecii-piece was inserted by screw-threads within the principal rein- force band abutting against the inner tube of steel, it was burst by the lengthwise expansion of the inner tube, pushing out the whole breech, breaking the reinforce band transversely!. Compare this ex- ample with the Whitworth gun shown in General Gillmore's report, and with those Parrotts that have failed at the breech, and see the analogy. The bursting of Parrott guns has also been attributed to the fail- ure of the gunners to put the shot home. Colonel Rodman shows, by a series of experiments by firing charges of powder in a shell, the heaviest of which only half filled the chamber, that the greater the proportion of volume of space to the volume of the charge, the less the destructive effect upon the walls. And even if the effect of the vis viva of the gases against the shot and the wall of the gun immediately behind the shot were greater than the effect of the pressure, it would not account for the transverse fracture or the blowing out of the breech; neither can *At this round the four bolts gave way the four united being equal to a solid bar the size of the bore. The rest of the gun was uninjured. * * * I had this gun re-made, with four bolts of the best charcoal iron, but they, too, broke without injury to the tubular part. Paper read by Captain Blakelcy before the United Service Institution, England; vol. Ill, Journal. t See Plate X, Fig. 1 t See Plate X, Figs. 3 and 4. $ See Plate VIII. EXPERIMENTS ON HEAVY OEDNANCE. 205 this particular fracture be accounted for by the sand getting into the bore, as in General Gillmore's practice on Morris island. For the same reason, if the shot is projected toward the muzzle its vis viva cannot be expended upon the breech. If the theory of unequal expansion from the heat of firing is accepted, it completely explains all the phenomena, but it also has this other effect it brings us to the conclusion that all our guns have been erroneously made $ for if we fabricate a gun in the best manner to resist the pressure of the powder, i. e., with initial tension, it is in the worst state to withstand the unequal expansion. In 1862 I advanced the same views I am herein advocating, but they interfered with the patented plans of ordnance officers or others in intimate rela- tions with our ordnance department, charged with the duty of procur- ing all the guns of government, and hence have never received the attention they deserve. I foretold that our guns would fail whenever they " received a fair and regular trial of their powers of resistance to the proper strains of actual service," which Mr. Parrott indicates very strongly they have not yet been subjected to. For guns that would smash " British and French iron-clads into eter- nal smithereens," or annihilate Charleston, our foolish and fond people, the tax-payers, would be willing to pay the hundreds of millions charged to them, on that account. It should be recollected that we have, perhaps, eighty heavy guns (mounted in turrets) of which the carriages " for what is a ship but a gun-carriage ?" says Admiral Dahlgren have cost about one million of dollars each, and these guns are ordinarily capable of being fired only once in fifteen minutes each, except as at the bombardment of Fort Fisher, (where two out of eight failed from rapid firing fired on that occasion one shot in three minutes from each gun.) The whole fleet of turret iron-clads, during a bombardment, can at this rate fire but about five shots a minute. The Minnesota, it is said, can fire a shot from her fifty-two guns in every thirty seconds of time each about one hundred shots per minute, equal to five whole fleets of iron dads. , The guns of our iron-clads have been long in service, and what have they done ? One shot struck the pilot house of the Atlanta, doing some damage ; one struck the stern of the Tennessee, but did not penetrate. Where is the record of any other service ? We know that Fort Mc- Allister was bombarded eight hours, inflicting but little injury to the works ; and in an attack on Fort Sumter by nine iron-clads, last- ing forty minutes, five of the nine were disabled. Our forces on Morris island were balked of success for a whole campaign, under the skilful and brave General Gillmore, for the want of guns ; 23* of those Parrott bombards burst in the action ; and who will attribute the want of success to any other cause? Yet Mr. Parrott writes you, regretting that Gen- eral Gillmore " should undertake to assign limit to the endurance of his guns." The last paragraph of Mr. Parrott's letter is most significant. He says, " I well know that nothing stands in the way of real improve ment, so much as attributing failures to a wrong cause." If " consid- erations far beyond the interests or feelings of an individual" influence him, let him now heartily assist the good work of opening up the busi- ness of inventing and fabricating guns to outsiders, and no longer be connected with that close corporation, the regulars, more familiarly known by the soubriquet u West Point." Eespectfully, NOEMAK WIAED. WASHINGTON, January 30, 1865. * It has since been found out that more than 50 of this kind of guns burst on Morris Island. 206 EXPERIMENTS ON HEAVY ORDNANCE. RELATIVE POWER OF ENGLISH AND AMERICAN GUNS. [From the report of Captain R. H. Noble, royal artillery, to the ordnance select committee, dated Woolwich, England, 27th August, 1866.] Table giving the remaining velocities and "work" of spherical steel solid shot fired from 15-inch and 11-inch guns. Gun. Charge. Projectile. Initial velocity. At 200 yards. At 500 yards. At 1,000 yards. s tf I Q Remaining velocity. > Remaining velocity. cs >. bo S f^ 'a .-S || Vis viva. Lbs. Lbs. Inches. Feet. Feet. Tons. Feet. Tons. Feet. Tons. 15-inch 11-inch 50 20 484 189 14.85 10.85 1,070 1,080 1,028 1,019 3,547 1,361 969 936 3,152 1,148 880 818 2,599 877 From this table we can approximately determine the effect of 15 -inch and 11-inch steel projectiles. Thus, assuming that the penetration* varies universally as the diame- ter, and that it requires 2,642 tons of "work" on impact to send a steel shot of 9". 14 through the side of the Lord Warden, the penetration of a steel shot from the 15-inch gun will require a force represented by the following proportion : 9.14 : 2,642 :: 14.85 : x and x = 4,292 tons. It would, therefore, require a force of 4,292 tons to send a steel shot 14.85 inches diameter through the Lord Warden. A glance at the last table shows that the 15-inch gun is unable to accomplish this even at a range of 200 yards, and it is further very doubt- ful whether this gun, fired with 50 pounds of powder, which is as heavy a charge as it will stand, and a solid steel shot of 484 pounds, w^ould pene- trate the side of the iron-clad ship Lord Warden, even were the muzzle of the gun touching the armor plates of the vessel. It is needless to remark that the 11-inch gun would be much less effective. These conclusions go to prove 1st. That the 7-inch muzzle-loading rifled gun of 134 hundred weight, fired with a solid elongated steel shot of 100 pounds, and charge of 25 pounds, is not capable of piercing the Lord Warden at any range. 2d. The same remark applies to the 100-pounder smooth-bore gun with a spherical steel shot of 104 pounds and 25 pounds charge. 3d. The 9.22-inch rifled gun of 12 tons, fired with an elongated steel shot of 221 pounds and 44 pounds charge, is capable of piercing the Lord Warden up to a range of about 1,000 yards. 4th. That the same remark applies to the 10.5-inch gun of 12 tons, fired * Vis viva has been given in foot-tons instead of foot-poimds, in consequence of the num- ber of figures required to express the latter. We 2 where W= weight of shot. v = velocity on impact. g =the accelerating force of gravity. By penetration is meant actual perforation through the plate, or the power of passing through the plate. In the case of penetration into iron plates, the term indent has been used. EXPERIMENTS ON HEAVY ORDNANCE. 207 with a solid elongated shot of 301 pounds and charge of 45 pounds, and to the present 9-inch service gun of 12 tons. 5th. That the American sniooth-bore guns of 15, 13, 11, and 9-inch calibre, fired with solid spherical steel shot, and the highest charges which they will bear with safety, are not capable of piercing the Lord Warden at any range whatever. 6th. This vessel could steam past batteries armed with the above smooth-bore guns without suffering except from "racking" effect. THE BELLEROPHON. ' The trial of this target was of such an undecided character and of such a comparatively mild form that it is difficult to obtain sufficient data upon which to base any comparison between this vessel and other iron- clads. The most severe blow it encountered was from the 10.5-inch rifled gun with a spherical steel shot of 165 pounds and charge of 35 pounds, the striking "work" being 2,472 tons. This shot failed to penetrate the target, but we have no evidence to prove that the 10.5-inch gun would not have penetrated with a charge of 50 pounds and striking "work" of 2,898 tons. The Bellerophon is undoubtedly of a stronger construction than the Warrior and Minotaur class, but there is no direct evidence to prove that it is as strong or stronger than the Lord Warden. We have seen that 75.4 foot-tons per inch of shot's circumference has failed to penetrate the Bellerophon, but it appears that this force is quite sufficient to penetrate this target when the plates are 5.5 inches thick instead of 6 inches (rounds 949 to 952). W^e have no evidence, however, whether 75 foot-tons per inch may not be too much for a Bellerophon with 5.5-inch plates. If we assume that this force is only sufficient for the penetration of 5.5-inch plates on a backing and skin similar to the Bellerophon, the latter with 6-inch plates would require a force of 89.6 foot-tons per inch, which is about what is required by the Lord Warden. The fact, however, of the 10.5-inch gun having failed to pierce this target indicates that the American smooth-bore 15 and 11-inch guns fired with solid steel shot, and the highest charges they are capable of bearing with safety, would not penetrate it at any distance over 100 yards. This vessel, therefore, could pass batteries so armed without suf- fering except by " racking." THE WARRIOR. We see from the table* that the 7-inch rifled gun is capable of piercing the side of this vessel with a 100 pounds shot and 20 pounds charge, the striking "work" being 1,374 tons, (round 1,018). The effect of the 100-pounder gun would therefore be represented by the proportion 6.91 : 1,374 : : 8.87 : a?, and x == 1,764. The force, therefore, required to send a steel shot from the 100-pounder gun through the Warrior would be about 1,764 tons, and we may assume that any force under this would not produce the required effect. Thus we find, round 972, that a shot from the 100-pcuuder struck the Warrior with a force of 1,573 tons, but failed to penetrate. * Appendix, page 38. 208 - EXPERIMENTS ON HEAVY ORDNANCE. In the same manner we can approximate to the force required to send a shot from the 9.22-inch gun through the Warrior 6.91 : 1,374 : : 9.14 : x, and x = 1,813 tons. The 9.22-inch gun could therefore send a steel shot through the War- rior, provided the striking force were 1,813 tons. If the shot, therefore, was 221 pounds weight, the necessary velocity would be 1,087 feet, and if the gun were fired with its full charge of 44 pounds it would send an elongated steel shot of 221 pounds through the Warrior at about 2,000 yards range.* In the same manner, in the case of the 10.5-inch gun, we have the pro- portion 6.91 : 1,374 : : 10.43 : a?, and x 2,074. The 10.5-inch gun would therefore send its shot through the Warrior, provided the striking force were 2,074 tons. From this it appears that the Warrior is of weaker construction than the Lord Warden, as the 10.5-inch gun failed to penetrate the latter with a striking force of 2,898 tons. In the case of the 15-inch American guns, we have the proportion 6.91 : 1,374 : : 1,485 : a?, and x = 2,953 tons. From Table XII, it appears that the 15-inch gun fired with a spherical steel shot of 484 pounds, and a charge of 50 pounds, would penetrate the Warrior at any distance up to 500 yards, but would not do so at 1,000 yards. In the case of the 11-inch gun we have 6.91 : 1,374 : : 10.85 : x, and x = 2,157. And from Table XII, we find that the 11-inch gun fired with a solid steel shot of 189 pounds and charge of 20 pounds would not penetrate the Warrior at any range, not even if the muzzle of the gun were touch- ing the armor plates. From these considerations the following effects are probable: 1. The 7-inch muzzle-loading rifle gun of 130 hundred weight, with a solid shot of 100 pounds, and charge of 25 pounds, is capable of piercing the side of the Warrior up to a range of about 600 yards.t 2. The 100-pounder smooth-bore gun (9-inch) of 125 hundred weight, with a solid spherical steel shot of 104 pounds weight and 25 pounds charge, is not capable of piercing the Warrior at any distance over 100 yards. 3. The 9.22-inch rifled gun of 12 tons with a solid elongated steel shot of 221 pounds and charge of 44 pounds is capable of piercing the War- rior up to a range of 2,000 yards. J 4. The 10.5-inch rifled gun of 12 tons with a solid elongated steel shot of 301 pounds and charge of 45 pounds is capable of piercing the War- rior up to a range of 2,000 yards. 5. The American 15-inch gun of 22 tons with a spherical steel shot of 484 pounds and charge of 50 pounds is capable of piercing the Warrior up to a range of 500 yards. 6. The American smooth-bore 11-inch and 9-inch guns fired with solid sperical steel shot and their maximum charges are not capable of piercing the Warrior at any range. * At this range the projectile will strike at a certain angle corresponding to the angle of descent, but with rifled projectiles this angle is very small, and may practically be neglected. t The same result would probably occur with the present service charge for this gun, viz. 22 pounds, and shot of 115 pounds t The same result would occur with the service 9-inch gun of 12 tons. EXPERIMENTS ON HEAVY ORDNANCE. 209 7. This vessel could pass batteries armed with 15-inch guns, as above, at a distance of 800 yards, without suffering, except by "racking." THE MINOTAUR. This class differs from the Warrior in having one inch of iron armor plating substituted for nine inches of wood backing. In the trial of this target an experimental powder named 2 A 4 was made use of, and this accounts for the effects observed with the 10.5-iiich gun. It appears from Table XIV that when the ordinary service powder was used the result was something the same as in the case of the Warrior. The actual strength of these ships may therefore, in absence of direct evidence to the contrary, be assumed to be equal ; but whether the wood and iron, which, combined, form the mass of resistance, have been more advantageously distributed in the construction of the Warrior than in that of the Minotaur, is a separate question. On the whole, it may be assumed that the remarks which apply to the Warrior are equally applicable to the Minotaur and ships of her class. THE HERCULES. This target was by far the strongest ever tried at Shoeburyness, and accordingly it received the most severe treatment. The preliminary experiments were made with the 9".22^ 10".5, and 10" rifled guns of 12 tons, firing solid steel shot with very high charges. It appears that rounds 1041, 1045 penetrated the 8-inch plate, and forced the pieces into the 12-inch wood backing. Both these rounds struck between two ribs ; 1045, however, met with more resistance than 1041, as it struck just over one of the horizontal plates; the armor plate was thus supported in rear of the point struck by a rigid backing. An 8-inch plate unbacked requires 88.5 foot-tons per inch of shot's circum- ference to just penetrate it;* it was to be expected, therefore, that the above rounds should do so. Rounds 1043, 1C 44, 1040, 1042, struck the 9-inch plate, which, if unbacked, would require a fore of 112.1 foot-tons per inch of shot's cir- cumference to penetrate it. Bound 1044 was therefore the only shot which had sufficient force to penetrate the plate, and this round struck both on a rib, and full on one of the rigid backings; 1040 almost penetrated the plate, as although the absolute indent was only 4.5 inches the piece of plate struck was almost dislodged; 1042 ought to have done more damage than it did; probably the steel was not of the best quality. The target was subsequently tested by firing at it with the 13-inch wrought-iron gun of 22 tons, using solid steel and chilled iron shot of 570 pounds with 100 pounds of powder. The gun was at 700 yards from the target. > The results proved that the target was impenetrable when struck fair, although it was penetrated by a chilled shot which struck just above a previous round.f When it is considered that this target was only 18.2 feet x 8 feet x 4 feet, and that it received blows amounting in all to over 70,000 foot-tons, it must be confessed it did its duty. * With a hemispherical-headed shot. t It is probable that this target would have been penetrated had the steel projectiles been ogival-headed, as suggested on minute lti,025. Rep. Ko. 206 14 210 EXPERIMENTS ON HEAVY ORDNANCE. THE SMALL PLATE. This target represented a wooden ship armor-plated, such as the French Flandres, &c. It appears that this class of iron-clad is not quite as strong as that represented by the Warrior or Minotaur, which are iron vessels armor- plated, and of course not nearly as strong as the Lord Warden or Bell- erophon. Thus the 10.5-inch gnu, with a striking "work" of 1,657 tons, pene- trated the "small plate' 7 target; and we have seen that this gun would require a striking force of 2,047 tons to send the same shot through the Warrior. It is hardly fair, however, to take this round (850) for the basis of a comparison with other guns, as it appears that the target had been previously considerably shaken. On the whole it may be assumed that vessels of the class represented by the "small plate" target are something weaker than those represented by the Warrior, and that the remarks which apply to the latter are applicable to the former in a greater degree.* THE 8-INCH TARGET. This target, as before stated, was designed for the trial of various descriptions of steel and chilled iron projectiles. The guns used in this experiment were the 8 and 9-inch muzzle-load- mg Woolwich rifled guns firing service charges. The results of this practice are fully given in table XIY, in the appen dix, and may be briefly summed up as follows: 1. The target was proof against all projectiles when tired at obliquely. 2. The target was not penetrated when fired at direct, except by the Falliser chilled projectile having a head struck with a radius of L5 diameters. This projectile was therefore clearly the victor, but whether ihis is owing to its being in the form of a shell or to its bursting charge, ve have no direct results to show. 3. It is probable that had the wood and iron which compose the target been differently distributed the resistance would have been greater. As, liowever, the target was built for a special purpose, this was not one of the conditions to be fulfilled. 4. It is proved that a pointed projectile of 7.92 inches in diameter can cut a hole in an 8-inch plate provided it strike with the necessary work . 5. As a rule these experiments coincide with previous trials, with the exception of the Palliser shell, which penetrated. This projectile accom- plished more than calculation would lead us to expect. Some further experiments will be necessary to determine the value of fc for this form of head. The following table shows the probable distance at which various guns, firing solid steel shot with full service charges, would penetrate iron-clad ships at present (1866) in the service. * This target is of equal if not superior strength to the Warrior, if struck on-the 5.9-inch plates. EXPERIMENTS ON HEAVY ORDNANCE. 211 APPENDIX E. List of guns burst and disabled in the army and navy since 1861; preparal from reports and evidence before the Joint Committee on Ordnance. Navy Parrott 100 pounder rifle gun, No. 2, burst at the muzzle on the steamer Hunchback, June 19, 1864. Navy Parrott 100-pounder rifle gun, No. 4, burst at the reinforce, and through the band in several places, on the steamer Westfield, October 31, 1862. Navy Parrott rifle gun 100-pounder, No. 6, burst at muzzle and chase on the steamer Mahaska, 1863. Navy Parrott 100-pounder gun. No. 11, burst at the muzzle on the steamer Commodore Barney, April 10, 1862. Navy Parrott 100-pounder rifle gun, No. 18, cracked in rear of vent or. the steamer Genesee, May, 1864. Navy Parrott 100-pounder rifle gun. No. 21, burst at muzzle on Cim- arroii, February 15, 1864. Navy Parrott 100 pounder rifle gun, No. 24, burst from trunnion to rear of band on the Paul Jones, July 18, 1863. Navy Parrott 100-pounder rifle gun, No. 25, cracked in two places ar vent on Sassacus, January, 1865. Navy Parrott 100-pounder rifle gun, No. 29, burst by blowing off breech on the Juniata, December 25, 1864. Navy Parrott 100 pounder rifle gun, No. 44, burst at breech on Com- modore Perry, June 17, 1864. Navy Parrott 100-pounder rifle gun, No. 135, cracked at the vent, Forfc Jackson, June 14, 1865. Navy Parrott gun 100-pounder ; No. 141, burst at the breech, which was blown out on the Mackinaw, December 26, 1864. Navy Parrott gun 100-pounder, No. 149, cracked at the top of the bore and around the breech on the Commodore Read, November 14, 1864. A*rrny Parrott 100-pounder gun, No. 1,* burst through the breech, band, and reinforce, to forward of the trunnions, on the revenue steamer Naugatuck, called the Stevens' Battery, in the James river, during the attack on Fort Darling, May 15, 1862. Navy Parrott 100-pounder Parrott gun, No. 150, cracked at the venfc on Commodore Read, November 14, 1864. Navy Parrott 100-pounder rifle gun, No. 162, burst at the muzzle on the Ticonderoga, November 14, 1864. Navy Parrott 100-pounder rifle gun, No. 166, burst by blowing oft breech off Fort Fisher on the Yantic, December 24, 1864. Navy Parrott 100-pounder, No. 194, rifle, cracked through the vent on the Maumee, June, 1865. Navy Parrott 100-pounder rifle gun, No. 213, cracked at vent on the Kansas, December 24, 1864. Navy Parrott gun, 100-pounder, No. 233, cracked on the outside from trunnion to band on the Osceola, June 15, 1865. Navy Parrott 100-pounder rifle gun, No. 238, cracked on the outside from trunnion to band on the Mendota, July 24, 1864. Navy Parrott 100-pounder rifle gun, No. 262, burst at muzzle on Talla- poosa, April 5, 1865. Navy Parrott 100-pounder rifle gun, No. 283, burst on the Mohican, December, 1864. * It appears that this gun, although the first of its class, was put in service without being- subjected to extreme proof. Its failure did not deter the ordnance department from pur- chasing, subsequently, a large number of similar guns. 212 EXPERIMENTS ON HEAVY ORDNANCE. Navy Parrott 100-pounder rifle gun, No. 311, burst into 10 pieces on the Ticonderoga, December 24, 1864. Navy Parrott 100-pounder rifle gun, No. 325, cracked through vent on the Lenapee, February, 1865. Navy Parrott 100-pounder rifle gun, No. 330, cracked through vent on Lenapee, February, 1865. Army Parrott 100-pounder rifle gun, No. 104, burst on Morris island a section of the reinforce thrown off in front of the band. The gun burst at the 216th round. Army Parrott 100-pounder rifle gun, No. 21, burst by throwing off a large piece of the reinforce in front of the band on Morris island at the 1,150th round. Army Parrott 100-pounder rifle gun, No. 158, burst on Morris island at the 256th round, a large piece of reinforce thrown off in front of the band. Army Parrott 100-pounder rifle gun, No. 19, burst on Morris island at the 128th round ; a large piece broken off in front of band. Army Parrott 100-pounder rifle gun, No. 161, burst on Morris island at the 377th round ; the gun burst through breech and the band, and the frac- ture extended forward in front of trunnions. Army Parrott 100-pounder rifle gun, No. 53, burst on Morris island at the 152d round; burst through breech, band, and reinforce to forward of trunnions. Army Parrott 100 pounder rifle gun, No. 157, burst, throwing off a large piece in front of the band, at the 219th round. Army Parrott 100-pounder rifle gun, No. 153, burst forward of the band and to the chase in front of the trunnions, at the 138th round. Army Parrott 100-pounder rifle gun, No. 66, burst in front of the band, on Morris island, at the 331st round. Army Parrott 100-pounder rifle gun, No. 95, burst at muzzle, on Mor- ris island, at the 87th round. Army Parrott 100-pounder rifle gun, No. 736, burst through band, breech, and reinforce, to forward of the trunnions, at 514th round, on Morris island. Army Parrott 100-pounder rifle gun, No. 155, burst through breech, band, and reinforce, to trunnions, on Morris island, at 126th round. Army Parrott 100-pounder rifle gun, No. 97, burst through breech, band, and reinforce, forward to trunnions, on Morris island, at the 439th round. Army Parrott 100-pounder rifle gun, No. 51, burst forward of the band, beyond the trunnions, nearly half the length of the chase, on Morris island, at the 214th round. Army Parrott 100-pounder rifle gun, No. 154, burst by blowing off breech, on Morris island, at the 38th round. Army Parrott 100-pounder rifle gun, No. 66, burst in front of the band, forward to front of the trunnion, and breech blown out, on Morris island, May 9, 1864, at the 108th round. Army Parrott 100-pounder rifle gun, No. 99, cracked on outside from band, to forward of trunnions, at 6th round fired on Charleston, May 15, 1864. Army Parrott 100-pouuder rifle gun, No. 14, burst in rear of trunnions into eight pieces, and band into two pieces, on Morris island, May 19, 1864, at 1,100th round. Army Parrott 100-pounder rifle gun, No. 156, burst in front of band, at 13th round fired upon Charleston, May 27, 1864. Army Parrott 100-pounder rifle gun, No. 100, burst in front of band, on Morris island, June 6, 1864, at 226th round. EXPERIMENTS ON HEAVY ORDNANCE. 213 Army Parrott 100-pounder rifle gun, No. , burst in front of band, on Morris island, July 15, 1864, at 491st round. Army Parrott 100-pounder rifle gun, No. 23, cracked outside from band to trunnions, at 1,480th round, September 4, 1864. Army Parrott 100-pounder rifle gun, No. 187, burst through breech and reinforce, at 316 rounds, September 12, 1864. Army Parrott 100-pounder rifle gun, No. 186, burst by blowing off breech, at 31st round, September 13, 1864, on Morris island. Army Parrott 100-pounder rifle gun, No. 162, burst into a large num- ber of pieces, some of which were thrown out of the battery. The shell at the charge which burst the gun, was thrown 4 r OOO yards, September 17, 1864, Morris island. Navy Parrott 100-pounder rifle gun, No. 81, burst at breech and re- inforce into many pieces, some of which were thrown a great distance. The shell at time of bursting (883d round) reached Charleston from Mor- ris island. Navy Parrott 100-pounder rifle gun, No. 128, burst in front of band, in service against Charleston, at the 914th round, November 14, 1864. Navy Parrott 100-pounder rifle gun, No. 34, burst at muzzle used against Charleston by army at 1,225 rounds, November 12, 1864. Army Parrott 100-pounder rifle gun, No. 18, burst in front of band and band injured; used against Charleston; burst at 454th round, November 15, 1864. Army Parrott 100-pounder rifle gun, No. 67, burst through breech and band. The band was broken into three pieces. The shell reached Charleston from the gun in Fort Wagner at the round at which the gun burst, November 15, 1864. Army Parrott 100-pounder rifle gun, No. 190, burst all in rear of trun- nions into many pieces, at the 102d round, in Battery Gregg, November 28, 1864. Army Parrott 100-pounder rifle gun, No. 189, burst in front of band, 196th round; mounted in Battery Gregg, November 29, 1864. Army Parrott 100-pounder rifle gun, No. 52, burst breech and rein- force into many pieces, at 1,590th round; Battery Chatfield, against Charleston. Navy Parrott rifle trial giin, No. , burst at the 420th round, 15-pound charges ; its calibre was 8 inches 150-pounder. Navy Parrott rifle gun, No. 6, (150-pouuder, calibre 8-inch,) cracked in action, on the monitor Patapsco. Navy Parrott rifle gun, No. 40, (calibre 8-inch, 150-pounder,) cracked in service, on the monitor Patapsco. Army Parrott 8-inch rifle gun, 150-pounder, No. 36, burst by blowing off the breech, at the 226th round, on Morris island. Army Parrott 8-inch rifle gun, 150-pounder, No. 25, burst by blowing off breech, at 230th round, on Morris island. Army Parrott 8-inch rifle gun, 150-pounder, No. 5, burst at breech, at the 227th round, on Morris island. Army Parrott 8-inch rifle gun, 150-pounder, No. 8, burst at breech, and reinforce, at the 522d round, on Morris island. Army Parrott 8-inch rifle gun, 150-pounder, No. 4, cracked on the out- side from breech to trunnion, at the 599th round, on Morris island. Army Parrott 8-inch rifle gun, 150-pounder, No. 6, burst at breech, at the 36th round, on Morris island. Army Parrott 8-int?h rifle gun, 200-pounder, No. 3, burst at breech, at 272d round. Shell reached Charleston at the round at which the gun gave way fired from Battery Chatfield October 1, 1864. 214 EXPERIMENTS ON HEAVY ORDNANCE. Army Parrott 8-inch rifle gun, 200-pounder, No. , burst in breech., band, and reinforce into many pieces, at the 1,063d fire mounted in Bat : tery Gregg August 15, 1864. Army Parrott 8-inch rifle gun, 200-pounder, No. 24, at 269th round crack was seen on the outside from band to trunnion, the crack ex- tended from the inside ; Battery Ohatfield, August 5, 1864. Army Parrott 8-inch rifle gun, 200-pounder, No. 25, cracked 011 side of breech outside and continued under bands to trunnion 578 rounds July 30, 1864. Army Parrott 8-inch rifle gun, 200-pounder, No. 20, burst at breech and cracked inside, at 1,457th round, July 23, 1864. Navy Parrott 8-inch rifle gun, 150-pounder, No. 6, cracked at muzzle, on Patapsco, July 22, 1863. Navy Parrott 8-inch rifle gun, 150-pounder, No. 28, cracked on outside around breech, rear of vent, on Shenandoah, February, 1864. Navy Parrott 8-inch rifle gun, 150-pounder, No. 46, cracked in bore, on monitor Onondaga. Navy Parrott 8-inch rifle gun, 150-pounder, No. 59, burst in chase and muzzle, on the Pequot, September 12, 1864. Navy Parrott 8-inch rifle gun, 150-pounder, No. 60, cracked on outside from band to trunnion, on Colorado, December 25, 1864. Navy Parrott 8-inch rifle gun, 150-pounder, No. 61, cracked at vent, on monitor Onondaga, April, 1865. Navy Parrott 8-inch rifle gun, 150-pounder, No. 82, burst, piece of muzzle blown off, on Susquehanna, June 15, 1865. Navy Parrott 8-inch trial rifle gun, 150-pounder, burst at Castle Island, at the 420th round 15-pound charges of powder. Army Parrott 10-inch gun, 300-pounder, No. 1, burst at muzzle, at the 27th round, on Morris island. This gun was repaired by chipping off the broken part, and burst again at the 37th round. Army Parrott 30-pounder rifle gun, No. 193, burst forward of the band, at the 4,606th round, on Morris island. Army Parrott 30-pounder rifle gun, No. , burst in breech and band into many pieces, at the 2,900th round, in Battery Gregg, May 15, 1864. Army Parrott 30-pouuder rifle gun, No. 18, burst at muzzle, 401st round, July 7, 1864. Army Eodman 8-inch rifle gun ? burst December 4, 1865, at the 1,047th round. Army Rodman 8-inch rifle gun, No. 1, burst at the 80th round. Army Eodman 12-inch rifle gun, burst on the 19th of February, 1868, at the 470th round ; the gun split through the breech and reinforce for- ward to within four feet of the muzzle. Army Eodman 12-inch rifle gun, No. 2, has been fired eight rounds, at Fort Monroe, and is reported injured. Army Eodmau 12-inch rifle gun, No. , has been fired two rounds, at Fort Delaware, and is reported as injured. Navy 12-inch rifle, cast hollow on the Eodman system and rifled on Mr. Parrottfs plan, burst at the 27th fire. Navy 12-inch rifle gun, cast hollow on the Eodman system and rifled on the plan of General Eodman, was badly cracked at the 16th round, when firing stopped. Navy 12-inch rifle, cast hollow and on the Eodman system and rifled on the Atwater plan, burst at the 30th round. Navy 15-inch gun, in the monitor Miantonomoh, rjored four inches too deep. Condemnable, and to be replaced. Navy 15-inch gun, No. 19, on the monitor Canonicus, at 351 fires " reports contradictory.' 1 EXPERIMENTS ON HEAVY ORDNANCE. 215 Navy 15-inch gun, No. 25, sold at auction for cracks in the vent, 9th fire. Navy 15-inch gun, No. 26, sold at auction for cavities in the chamber, 9th fire. Navy gun No. 29, 15-inch, burst the Saugus. This gun split through the breech, at Fort Fisher, at the 243d fire. Navy 15-inch gun, No. 13, cracked in service, on the monitor Lehigli. Short 15-inch navy gun, No. 24, surveyed and condemned December, 1865, from monitor Monadnock, after the 168th fire. Short 15-inch navy gun, No. 27, surveyed and condemned December, 1865, from monitor Monadnock, after the 161st fire. Navy 15-inch gun, No. 12, cracked at the vent at the 132d round, on t&e monitor Onandaga. Navy 15-inch gun, No. 14, cracked at the vent, on the monitor Onan- daga, at the 96th round. Navy 15-inch gun, No. 1, (trial gun,) burst at the 868th fire. Navy 15 -inch gun, No. 34, reported to be in a doubtful condition after fche 363d fire. NOTE. Of the first 34 numbers of 15-inch guns procured for the navy for use in the turrets of the monitors, 12 are burst or disabled. The whole number of rounds fired from all these guns altogether has been 5,448, equal to 160 rounds per gun. Navy 15-inch gun, No. 23, at 358 fires was reported to be in doubtful condition ; it was mounted in the monitor Canonicus. Navy 15-inch gun, No. 35, fired 131 rounds for proof, reported in doubtful condition. Navy 15-inch gun, No. 44, on the monitor Mahopac, split in the chase, at the 85th round. Navy 15-inch gun, No. 67, mounted on the monitor Puritan, cracked about the vent at 102 rounds, and was sold at auction for old iron. Navy 15-inch gun, No. 68, cracked in the vent at the 59th round, and was sold at auction for old iron. NOTE. Forty-two of the 15-inch guns purchased for the navy have never been fired more than nine proof rounds. Of 25 mounted in iroii-clads, which were fired an aggregate of 1,333 fires, equal to an average of 53 fires for each gun, four have been burst or disabled. SPONTANEOUS RUPTURE. Navy 11-inch Dahlgren gun found cracked at Eeadiug foundry, before the turning was completed, November 10, 1862. Navy 11-inch Dahlgren gun cracked before the turning was com- pleted, November 16, 1862, at Reading foundry, Pennsylvania. Navy 11-inch Dahlgren gun cracked previous to its completion at Sheading foundry, November 16, 1862. NOTE. The inspector gravely attributed the premature rupture of these guns to the swelling of the sand of the mould by heat. Navy gun 15 inch, (no number and no date,) burst while cooling, at the Fort Pitt foundry. Army 15-inch Eodman gun, No. 404, made at Eeadiug foundry, burst open nearly the whole length while in the lathe. The explosion of this great gun was attended with a loud report equal to a six-pounder gun. Army 15-inch Eodman gun, No. 419, cast at Eeading, Pennsylvania, burst in the pit after the removal of the core barrel. Army 15-inch Eodman gun burst in the pit at the Pittsburg foundry, having split the whole length. 216 EXPERIMENTS ON HEAVY ORDNANCE. Two army Rodman 10-inch guns cracked in the lathe. One army Rodman 10-inch gun, cast hollow and cooled from the. interior, burst in the lathe. MISCELLANEOUS. Naval wrought-iron gun, 80-pounder, made at Reading by Syfert, McManus & Co., was paid for February 8, 1864, the price being $5,607 86 for the forged block, to be finished at the Washington navy yard. While being finished, a flaw in the bore and another in the left trunnion were discovered. The gun was never submitted to test. Two army Ames guns, 7-inch calibre, made of wrought iron, burst in proof. Army Ames gun, 7-inch calibre, bored out to eight inches, burst at Fort Monroe, at the 26th round, after the enlargement. Army Rodman gun, 13-inch calibre, burst on the 27th July, 1864, at the 738th round. The gun broke through the breech and reinforce into a number of pieces. Navy Ericsson's 13-inch smooth-bore wrought-iron gun, made at a cost of $30,000, and paid for previous to test, was fired 40 rounds. The 'gun was reported unserviceable. A navy 13-inch Dahlgren gun, cast solid, at Providence, burst at the 172d round. One or two other 13-inch guns, made for the navy, showed but low endurance, but the committee have not been able to obtain particulars. Wiard's 15-inch navy gun, of cast-iron, first of the class, burst at Trenton, with a charge of 80 pounds of fine quick burning powder and a solid shot of 886 pounds' weight. The gun was improperly cooled, by which a lengthwise tension was inaugurated sufficient almost to break the gun before firing. The muzzle broke off before the shot had reached the point of fracture, as was shown by the shot having struck the frac- tured surface as it passed. The second gun, cooled differently, was never fired. The bureau annulled the contract (which provided for two or more trials) before the second gun was tested. The Whitworth 80-pounders, built up guns, mounted on Morris's island, were disabled, each, at the lllth round, by the lengthening of the inner tube, which protruded at the breech one inch in each case and shut off the vent. One of these had a crack in the exterior coil of the reinforce. Navy 11-inch gun, No. 1, exhibited cracks early during the proof, which extended to a length of 24 inches at the 1,958th fire, and it burst at the 1,959th round into three great pieces, the fracture running through the centre from the breech and branching off to either side forward of the trunnions. Two navy Dahlgren 80-pounder rifles were condemned as unservice- able, and sold at auction for old iron. Thirteen 50-pounder naval Dahlgren rifle guns, and 13 30-pounders of the same kind, were condemned and sold. Naval Dahlgren 30-pounder rifle, No. 54, cast solid at Washington navy yard, burst at 34th round. Navy Dahlgren 80-pounder rifle, cast solid at Fort Pitt foundry, burst at the 377th fire ; was made of cold-blast charcoal, iron. Navy Dahlgren 80-pounder rifle, cast solid at Fort Pitt foundry, burst at the 852d fire. Navy Dahlgren 50-pounder rifle, cast solid at Cornwall furnace, burst at the 204th fire. Naval Dahlgren 30-pounder rifle, No. 49, cast solid at navy yard, Wash ington, burst at the 742d fire. EXPERIMENTS ON HEAVY ORDNANCE. 217 Six navy Dahlgren 150-pounder rifle guns were sold at auction for old iron. Navy Dahlgren 7J-inch rifle-gun, 150-pounder, burst at the 27th round. Navy Dahlgren 7-inch rifle, 150-pounder, fired 75 rounds, reported unsatisfactory ; test not continued. Navy Dahlgren 7^-inch rifle, 150-pounder, fired 60 times, reported unsatisfactory ; test not continued. SUMMARY OF BURST GUNS. Parrott 100-pounders, (rifles) 60 Parrott 150-pounders, (8-inch rifles) ' 22 Parrott 10-inch rifles 1 Parrott 30-pounders 3 Hodman 12-inch rifles 4 Eodman 8-inch rifles 2 Eodman 15-inch smooth-bore, (navy) 17 Eodman 13-inch smooth-bore, (army) 1 Dahlgren 150-pounders, (rifles) 3 Dahlgren 80-pounders, (rifles) 2 Dahlgren 50-pounders, (rifles) 1 Dahlgren 30-pounders, (rifles) 2 Dahlgren 80-pounders, (condemned) 2 Dahlgren 50-pounders, (condemned) 13 Dahlgren 150-pounders, (condemned) 6 Dahlgren 13-inch smooth-bore 1 Dahlgren 11-inch smooth-bore 1 Miscellaneous wrought and cast-iron 9 150 Burst spontaneously 10 Cracked, fissured, or ruptured before proof 98 258 Eighteen Parrott 100-pounders, in addition to the above, are unac- counted for, supposed to be burst. Twenty-seven Parrott 150-pounders were condemned by the navy. Of 43 Eodman 15-inch guns, cast for the navy, which was the great- est number in service at any one time, 17 have burst or been disabled. Of three 12-inch Eodman rifles, cast for the navy, one was rifled on the plan of Mr. Parrott and burst at the 27th fire ; one on the plan of Atwater, burst at the 30th fire : one on the plan of Eodman, burst at the 16th fire. Of four Dahlgren 150-pounder rifles one burst at the 27th fire, one at the 20th fire, one at the 75th fire, and one at the 60th fire. One 13-inch gun, cast solid, at Providence, endured 178 fires. One 13-inch gun, cast hollow, at Pittsburg, endured 108 fires. The navy 15-inch guns cast on Eodman's plan are divided by Admiral Dahlgren into three classes : 1. The original Dahlgren model. 2. The same altered by Captain Wise. 3. The new model by Captain Wise. Of the first class 34 were cast, 17 were altered to the second class. Of these eight were disabled nearly Aa(/- after enduring but an average of 135 fires for each. Eep. No. 266 15 218 EXPERIMENTS ,ON HEAVY ORDNANCE. One-fifth of the unaltered guns were disabled after an average of 175 fires for each gun. Sixty-six guns were cast of the third class. The trial gun endured but 131 fires when it was disabled. Of the remaining 65, 40 have only been fired the nine proof rounds ; 25 have been mounted in iron-clads and have been altogether fired 1,333 times ; one burst, three condemned, two of them sold as old iron. One- fifth of these failed, being subjected to an average of 53 fires each. NOTE. The guns above enumerated are all the 15-inch Rodman guns, . which have been fired in service, none of the army guns having been so fired. The Eodmau gun was first officially adopted in 1862, by the ordnance board of which the inventor and patentee was a member. When General Dyer became Chief of Ordnance, in the fall of 1864, one of his first acts was to appoint General Rodman constructor of ordnance. He raised the price of the 15-inch gun to $7,000, which was previously $6,500, and issued an order to receive the guns made under the supervision of the constructor without subjecting tliem to the powder proof. Thus it can be seen that General Rodman has held in succession tbree important posi- tions in relation to the reception of his guns, one-twelfth of the whole price of which he has received as royalty, viz : 1st. Inventor and patentee while an officer of the United States army, and of the ordnance corps. 2d. A member of the ordnance board the power behind the throne which adopted his invention officially for the service of the United States. 3d. Constructor of ordnance, charged with the inspection and recep- tion of the guns in which he is interested as patentee, receiving a* royalty. Two hundred and ninety-six 15-inch guns have been received by the army ordnance department under this organization. Twelve hundred and thirty-three 10-inch Rodman guns, and 155 8-inch, for which carriages and a large supply of projectiles have been purchased. There is no data upon which to found an opinion that the Rodman gun, if subjected to service test, would have any special rate of endur- .ance. None of them, except those referred to above as used in the navy, have been fired in battle or service. A large proportion of them have ibeen mounted, without having been fired at all. The siege and sea-coast guns purchased by the army Ordnance Office from the 1st July, 1861, to June 30, 1866, cost $5,354,365 57 ; of this .amount $708,554 20 was paid for Parrott guns. The rest of this amount was paid principally for Rodman guns ; $3,230,526 32 was paid for Par- srott projectiles ; $289,105 80 was paid to Mr. Parrott for carriages for Ms 100-pounders, 200-pounders, and 300-pounders. The navy purchases from the Fort Pitt foundry, where the Rodman .guns were principally made, amounted to $2,116,052 62. The navy purchases from Mr. Parrott have not been ascertained. It as believed that more than 175 100-pounder guns were obtained. The number of the Dahlgren shell-guns which have been cracked or fissured .inside previous to proof, or during experiments or service, could not be learned. The chief of the bureau evaded the questions relating to the i)ad qualities of his own invention, while he was elaborate in his answers as to the bad qualities of the guns of other inventors. EXPERIMENTS ON HEAVY ORDNANCE. 219 EXPLANATION OF DIAGRAMS. PLATE I illustrates the fractures usually occurring in guns, which are of six descriptions, viz : 1. Eupture through the breech, along the reinforce, branching to either side forward of, or at, the trunnions, as shown in Fig. 1. This fracture is sometimes accompanied by cross fractures of the reinforce. 2. Eupture at the muzzle, as shown in Fig. 2. 3. Eupture caused by the blowing out of the breech, as shown in Fig. 3. 4. Eupture in banded guns, by which a slab is blown off the side ot 'the gun forward of the band, as shown in Fig. 4. 5. Cracks on the exterior of the gun, as shown in Fig. 5. 6. Cracks in the interior of guns. (Not shown by diagram.) PLATES II, III, and IV illustrate the general direction of fracture in unbanded guns, cast hollow and solid, and of the old and new models. Figs. 1 and 2, Plate II, represent interior and exterior lines of frac- tures in a hollow-cast 10-inch Columbiad, old model. Fig. 1, Plate III, shows the line of fracture in a hollow-cast of improved model, and Fig. 2 the line of fracture in a solid-cast gun of old model. Fig. 1, Plate IV, represents the latest improved model of a Eodman hollow-cast gun. Figure 2 represents a burst 13-inch gun of the same kind, showing the general direction of fracture to be the same as in the preceding diagrams. PLATES V and VI illustrate the cause of rupture, as shown by the direction of fractures, supposed to result from the combined effect of pressure and unequal heating. (See evidence of General Eodrnan, Gen- eral Gilinore, and Norman Wiard. PLATE VII illustrates the difference in the texture and strength of iron, caused by difference in the rate of congelation when cast. PLATES VIII and IX represent the Eodman external and internal pressure metres. PLATE X, fractures of guns at the breech. Fig. 1, Whitworth 80-pounder gun, with inner tube extended and protruding one inch at the breech. Fig. 2, Parrott 200-pounder gun, with breech blown out. Fig. 3, Armstrong 300-pounder, with breech blown out. Fig. 4, perspec- tive view from the rear of same gun after the accident. PLATE XI illustrates fissures and differences of texture in wrought iron. Figs. 1, 2, 3, and 4 show fissures resulting from unequal cooling. Fig. 5, crystallized wrought iron. Fig. 6, fibrous wrought iron. (See evidence of Norman Wiard, and Appendix D.) PLATE XII represents the Ames wrought-iron gun, and shows the method of building up the gun by welding together a succession of cross sections. PLATES XIII and XIV illustrate the method of fabricature and mount- ing of guns proposed by Norman Wiard, designed to provide for restrain- ing the force of pressure and unequal expansion, and to cause the recoil to be in the direction of the plane of the axis of the bore. PLATE XV, experimental castings illustrating the effect of unequal cooling on cast-iron. (See evidence of Norinan Wiard.) Plate I Tlg.l Fig. 3. n rig. 4. Fig. 5. Plate II Plate III Fig 2 Plate IV MEDIUM 13 INCH RODMAN CUN flan r i Plale V Fig. 1 Fig 2 FigS Fig 5 Fig 6 Fig 4 iff. 7. Plate YI 8 Inch. Columbiad. Kgl Fig 2 PlatcTII DIFFERENCES OF TEXTURE IN CAST IRON. J)a& to differences in/ the rat&^of 'congelation; of the/ same irons, whew cast w different sizes of mass. BY NORMAN WIARD r,g 2 Figl Fig. 4 Fig Fig. 1. cas-t 2 inches diameter, tensile strength '28,000 Fy. t. . 4 .. . " " 22,000 Fiq 3. 8 n . , MOOO R 4 . 12 ,, , 16.000. Plate VIII. 17 3. Plate IX RODMAN INTERNAL PRESSURE INSTRUMENT .Section on A B. Seclio/1 on C.D. Fitf.3. Plate X Plate XI .,;;.^- -,::-v Fig 1 o Fig3 > Fitf. (> Plate XII Plate :xm. Elevation or 200 PS." WIARD RIFLE Solid Section/ on/ ss. Section/ oiv tt. DETAILS. Combined JHfle and Smooth/ -tort*. 200 PB-* WIARD wA. CaLSin, Plate XIV. Plate XV UNIVERSITY OF CALIFORNIA LIBRARY THIS BOOK IS DUB ON THE LAST DATE STAMPED BELOW OCT 18 USE DEC 281960 LD REC'D LD JUL 31963 YC 6429! UNIVERSITY OF CALIFORNIA LIBRARY