Gunnery Department, 
 
BANCROFT LIBRARY 
 
 THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 J. Porter Shaw Collection 
 
 Gift of 
 Marguerite Bachrach 
 
INSPECTION 
 
 AND 
 
 PROOF OF CANNON. 
 
 WASHINGTON: 
 
 GOVERNMENT PRINTING OFFICE. 
 1864. 
 
BUREAU OF ORDNANCE, Navy Department, March 23, 1864. 
 
 SIR : The Bureau haa the honor to present the accompanying rules and regulations for 
 the "Inspection and Proof of Cannon" for the Navy. 
 
 These have been carefully compiled and revised by officers most experienced in ordnance, 
 and are approved by the Bureau. It therefore respectfully submits them for the adoption of 
 the Navy Department. 
 
 I am, sir, with high respect, your obedient servant, 
 
 H. A. WISE, 
 Chief of Bureau ad interim. 
 Honorable GIDEON WELLES, 
 
 Secretary of the Navy. 
 
 NAVY DEPARTMENT, Washington, March 30, 1864. 
 SIR: The rules and regulations for the "Inspection and Proof of Cannon," submitted 
 
 with your letter of the 23d instant, are hereby approved, and all officers of the Navy will 
 strictly observe and enforce them. 
 
 Very respectfully, 
 
 GIDEON WELLES, 
 
 Secretary of the Navy. 
 Commander H. A. WISE, 
 
 Chief of Bureau of Ordnance 
 
 ad interim, Navy Deparhment. 
 
A 2.^ 
 
 INSPECTION AND PROOF OF CANNON, 
 
 CONTRACTS. 
 
 Contracts for guns for the navy shall provide for the uniformity of the modo of their 
 niiinufiicture, as well as of the metal of which they are composed, which should bo of the best 
 quality attainable. 
 
 To this end, the Chief of the Bureau^of Ordnance, when he shall deem it important, may 
 employ some competent person to visit the furnaces from which the iron is to be supplied, and 
 examine the Various ores used, for the purpose of selecting the fittest kinds, and determining 
 their proper treatment for making gun-iron. 
 
 Experience having shown that certain kinds of metal and general modes of treatment are 
 essential to the production of guns of uniform endurance, these conditions will be insisted on. 
 But as it is also desirable to obtain the experience of the founder, .he will be the jivlge of the 
 particular metal and details of treatment, and will be required to produce a satisfactory trial-gun 
 in case of deviation from established processes. 
 
 .Before proceeding to execute a contract, a trial-gun may therefore be ordered, at the dis- 
 cretion of the Bureau, subject to the supervision of the resident Inspector, with reference 
 to material and treatment, and to be exposed to extreme proof with service charges. 
 
 After undergoing this proof in a manner satisfactory to the Bdreau, the trial-gun will servo 
 aa a standard, and the proportions of the several kinds of metal used, and the methods employed 
 in its<nanufacture, must be followed in all respects in the fabrication of the other guns. 
 
 A trial-gun may also be ordered by the Bureau, at any time when it may be reasonably 
 suspected that changes have occurred in the quality of the several kinds of metal usod ;it any 
 foundry, as is often the case from the use of different qualities of ores from the same bank, or 
 from the different workings of the same furnace. 
 
 But whether a trial-gun has been made or not, a gun may bo selected for extreme proof 
 with service charges, by the Chief of the Bureau, out of any lot of guns offered under contract, 
 as an exponent of the whole, to be paid for by the Bureau or not, as may be stipulated in the 
 contract. 
 
Contracts for guns are to comprise the following itetns, subject to such corrections and 
 additions as may be deemed necessary, from time to time, by the Bureau of Ordnance : 
 
 1st. In casting any particular lot of guns, iron from such furnaces, and in such proportions 
 of each grade or number; of pig, and such fuel is to be used, as may be decided on at the time 
 by the Bureau, concurrently with the founder. 
 
 2d. A proper proving ground is to be provided, and a suitable "butt" and "bomb-proof 
 shelter," when requisite, to be prepared by the contractor, and to be so situated that the 
 firing will not probably be interrupted by an interference of the authorities, the frequent 
 passage of vehicles, or other causes. The "butt" is to be so constructed as to allow the easy 
 recovery of projectiles, and the earth in it to be free from rocks, stones, or gravel ; the bomb- 
 proof shelter for the men is to be made safe and convenient of access. 
 
 3d. Either two skids or a ^proving carriage are to be provided by the contractor for 
 each gun to be fired. If skids be used, they are to be of sufficient thickness to keep the bores 
 of the guns level whilst their trunnions rest on the skids, and their breeches on the ground, 
 and of such length that the guns will not recoil clear of them. 
 
 4th. The ground is to be firm enough to prevent difficulty in transporting and handling 
 the guns. The guns are to be placed on the ground, at the expense of the contractor, who 
 should be also required to prevent the exposure of the guns to the weather, and to have them 
 thoroughly cleaned, should they be rusted, before prwof. 
 
 5th. The labor required in the proof will be paid for by the contractor. 
 
 6th. The contractor will furnish safe storage for the implements used in proof and inspec- 
 tion, without charge. The storage of powder and projectiles, and the transportation of them 
 to and from magazines, for the proof of guns, will be paid for by the Bureau. odMi'*^ VirwdL*- 
 
 7th. The manufacture, inspections, and proofs of all the guns contracted for, are to con- 
 form in all respects to the conditions prescribed and set forth in the specifications and drawings 
 annexed to and made part of the contract. 
 
 8th. The contractor is to afford facilities to the resident Inspector of ordnance for the 
 proper discharge of the duties required of him by these instructions, and by the specific 
 instructions given to him from time to time, by the Chief of the Bureau, in relation to the 
 manufacture, inspection, and proof of guns and projectiles. 
 
 9th. No payment is to be made to contractors for guns or projectiles until they shall 
 be delivered, in good order, at the place designated in the contract. 
 
 "The proving carriage is a simple frame of oak, with cheeks connected by transoms, which project beyond them sufficiently 
 for the handspikes to take. It has trunnion holes and cap-squares, which afford the means of proving the trunnions, as the 
 carriage is intended to slide on the ground. It presents the further advantage of saving much labor, as does the pendulum 
 in extreme proof. When a proving carriage is used, some means are required readily to mount and dismount the guns. 
 At several of the proving grounds permanent skids are arranged for the proof of cannon. The trunnions rest in a small chock 
 which slides on two of the skids, the breech resting on a third, of such height as to keep the gun level. They are placed at 
 an inclination of about eight degrees, and the gun generally returns to its position for loading after each fire. 
 
INSTRUCTIONS TO INSPECTORS RESIDENT AT FOUNDRIES. 
 
 L.The Inspector of Ordnance, resident at a foundry having a contract with or order from 
 the Bureau of Ordnance for the manufacture of guns or projectiles, is expected to attend daily, 
 during working hours, while any part of the work is in progress. 
 
 2. He is carefully to examine and note the kinds and qualities of the several lots of mate- 
 rials, including fuel, collected for the manufacture of guns or projectiles for the public service, 
 and to familiarize himself with the various processes employed in making guns and projectiles. 
 
 3. He is to keep a journal of his proceedings, and of the occurrences at the foundry or 
 elsewhere connected with the \vork in hand, noting therein every circumstance likely to be of use 
 for future reference and guidance, and comprising in his remarks as much reliable information 
 as is attainable upon all the points embraced in his specific instructions from the Bureau ; and 
 where, in any case, the information obtained is not the result of his own personal observation, 
 he will be careful to note the source from which it is derived. 
 
 4. He will also keep a separate and minute account of the materials and manufacture of each 
 gun, in reference especially to the points to which his attention may be called in his instruc- 
 tions, but also comprising, in his general remarks, every point which may suggest itself as ira- N 
 portant for reference. 
 
 / 5. He will see that each of the several kinds of metal and the fuel used is in itself of uni- 
 form quality, and bears the prescribed proportion to the whole charge of the furnace, which 
 [ charge is to be treated alike in making each gun contracted for. j 
 
 6. He will keep a careful record, in the prescribed form, of the manner of making moulds, 
 and the materials used in making them; of the character and proportion of each kind and quality 
 of metal of each charge of the furnace; the number of furnaces used ; the appearance of the 
 fractures of the pigs; the quantity and quality of the fuel; the state of the atmosphere; the 
 time required to fuse the whole charge, and the time it is kept in fusion before tapping; the 
 temperature of the runners and of the mould ; the arrangements for and the time occupied 
 in filling the mould; the mode of heating the pit and flask, and the temperatures thereof at 
 regular intervals; the mode and the time occupied in cooling the casting; the temperature of 
 the flask when hoisted out of the pit, and of the casting when taken out of the flask; and 
 every other particular which may be embraced in the contract or in his instructions,, or which 
 may present itself in the course of the operations and tend to secure uniformity and to facili- 
 tate comparison. 
 
 This record should also embrace, with dates, all the subsequent operations of cutting, turn- 
 ing, boring, chipping, and drilling, and the tests of the metal afforded by each of these pro- 
 cesses as to toughness, hardness, soundness, time required, color, as well as the measurement, 
 at various times, the tests of the samples, and the final inspections and proofs; a copy should 
 be left with the foundry for future reference. 
 
 7. He is expected, also, to note in his journal any particulars relating to the manufacture 
 of guus or projectiles making at the foundry for other parties, which may be either new or in 
 nny manner suggestive of improvement. 
 
6 
 
 He will keep the Bureau advised of the progress of the work, and of all departures from 
 the letter or spirit of the contract; and will, besides, make regular reports, on the last day of 
 each month, of what has been done in the course of it, in the prescribed form, with such addi- 
 tions as circumstances require. 
 
 8. He will make timely requisitions on the Bureau or on the nearest, navy yard, as directed, 
 subject to the approval of the Bureau, for such ammunition and implements as may be required 
 in the proof of the guns under contract. And he will see that all necessary and proper arrange- 
 ments are made on the proving ground in due season, and that the guns are properly placed 
 thereon by the contractor: and will notify the Bureau when everything is in readiness for the 
 final inspection and proof, in order that there may be no delay after the order is received at the 
 foundry. 
 
 9. He will not show to nor leave in the way of unauthorized persons any plans or drawings, 
 dimensions of guns, or the guns themselves, or any information respecting proofs or experi- 
 ments in progress, and is to discourage the doing so by the contractors or their agents. 
 This prohibition to form part of the contract as to contractor. 
 
 10. As soon as a lot of guns have been inspected and proved, according to the terms of the 
 contract and the instructions of the Bureau of Ordnance, the Inspector will forward his reports 
 thereon, and that on the mechanical tests of the samples, if not previously sent, to the Chief of 
 the Bureau for his decision. In his records and reports he will use the prescribed forms. 
 
 1 1. Guns are not to be received nor marked except with the Foundry numbers on the casca- 
 bel, nor are any bills for them to be approved by the Inspector until he shall have received au- 
 thority to that effect from the Bureau. 
 
 12. A certificate, in the form following, is always to accompany the bill of charges for ex- 
 penses incurred by the contractor in proving guns, viz : 
 
 r. 
 
 FOUNDRY, 
 
 ' / 
 
 I hereby certify that the alateriHjs charged In the foregoing bill/nave beenyused/and 
 authorized expenses charged therein incurred, it 
 made under contact with the Bureau of Onteance, by 
 
 the aphorized expenses charged therein incUp/ed, in proving. -/- \X guns 
 
 13. The bills must be made out in triplicate, and approved by the Chief of the Bureau, before 
 they can be paid by the navy agent. 
 
 After inspection, the bores of guns are to be oiled with fish oil. Oiling the outside would 
 prevent their being readily handled. 
 
FORM OF RECORD TO BE KEPT BY THE RESIDENT INSPECTOR AT THE FOUNDRY 
 
 FOR EACH GUN CAST. 
 
 Calibre and datt, . Foundry, No. . Weight in pound*. 
 
 Date i/7/i catt, 
 
 Mrtal. (Information to be ob- 
 tained in relation to the 
 furnace*, ores, anJ fuel 
 raed in smelting must he 
 obtained from the founder, 
 unless officers are gent to 
 the furnaces.) 
 
 From what ores, and the situation of ore beds. 
 From what furnace received. 
 Kind of fuel used in making the pig iron. 
 Cold, hot, or warm blast used in milking it. 
 
 General character and appearance of the pig iron, as respecta color, texture, 
 and. fracture. 
 
 {Weight of different kinds of pig iron used from different ores and furnaces for 
 this gun. 
 Weight used of different fusions of each kind of iron. 
 Total weight of metal for charge of furnace. 
 
 Relating to the process of 
 manufacture and cooling. 
 
 Kind of furnace. 
 
 Mode of preparing the hearth. 
 
 How many furnaces are used in melting iron for any one gun, and how do 
 their streams mingle before entering the mould. 
 
 Kind of fuel used. 
 
 Mode of firing. 
 
 Time required to obtain complete fusion. 
 
 Taking out specimens during the progress of melting. 
 
 Time kept in fusion. 
 
 How introduced into the mould of the gun. 
 
 What precautions are taken to prevent scoria entering the trunnions. 
 
 Time employed in filling the mould. 
 
 Dimensions of gun-head and nature of shrinkage 
 
 Arrangements for retarding the cooling. 
 
 Length of time the gun is left in pit for cooling. ' 
 
 Excess in the diameter in any part of the casting beyond the prescribed dimen- 
 sions of the gun. 
 
 Temperature of mould, ( at the time of casting, and after being opened, and 
 
 Temperature of pit, ) when the gun is hoisted out. 
 
 Position of the thermometer in the pit. 
 
 Temperature of the pit, and of the external air, at 8 a. m. and 4 p. m. daily, 
 during the time the gun is left in the pit for cooling. 
 
 Temperature of the air, and gun when it is detached from the mould. 
 
 Under the head of general remarks, any facts which may seem to the inspector 
 worthy of record. 
 
8 
 
 Qualities of the metal. 
 
 External imperfections, if any, of the gun when cleaned. 
 How does the metal work under the tools, hard, soft, or otherwise ? 
 Is it tenacious or brittle ? 
 Time occupied in boring the gun. 
 Time occupied in turning the gun. 
 Appearance of the bore, perfect or otherwise. 
 Appearance of surface after being brought down to true dimensions. 
 Appearance of core, sound or otherwise. 
 Appearance of core-metal at places of fracture. 
 Tenacity and density of specimens from gun-heads. 
 
 Tenacity and density of specimens from core taken between muzzle and trun- 
 nions. 
 
 Tenacity and density of specimens from nearly opposite to trunnions. 
 Tenacity and density of specimens from near the bottom of bore. 
 Any apparent causes for doubting the good qualities and. strength of the gun. 
 Any other useful information. 
 
 The Resident Inspector shall take accurate measurements of the different parts of the guns 
 as soon as they are finished. These examinations are for the information of all the parties, but 
 are not to be considered as decisive for reception. 
 
 As soon as the casting has been completed the information shall be collected and forwarded 
 to the Bureau of Ordnance, according to the form now in use, or that which shall be from 
 time to time prescribed. 
 
 The manufacture of rifled cannon and projectiles being consided as yet only experimental, 
 specific directions relative to their manufacture, inspection, and proof, will be given from 
 time to time as requisite. 
 
9 
 
 TENACITY AND DENSITY OF IRON. 
 
 The Resident Inspecting Officer will subject the metal of each gun to the usual tests of tena- 
 city and density, and for this purpose will take samples from the sinking head, the core, or 
 such other available parts of the casting, and in such manner as may be prescribed, and will 
 forward duplicate specimens to the Ordnance Yard at Washington for trial. 
 
 The axis of the sample is to be parallel to or at right angles with the axis of the casting, aa 
 may be required by the Bureau. Fairly to represent the metal of the gun, the samples from 
 the head should not be taken from the part opposite the bore, but opposite to the middle of 
 the thickness of the metal remaining in the gun after being bored and turned. The mass from 
 which the sample is taken, whether sinking head or core, must have the same foundry number 
 cast or stamped upon it as the gun to which it belongs, before being taken away from the 
 gun. Each sample must have the foundry number of the casting it represents ; and an initial 
 letter and a number, designating the part of the gun or gun-head from which it was taken, 
 and its distance from the axis of the bore, and from the base line, stamped upon both its ends. 
 To prevent confusion, the samples should be marked on one end before they are disconnected 
 from the mass, and should not be separated from it, except in the presence of the inspecting 
 officer. 
 
 When practicable, the tests are to be made at the foundry, before the guns are subjected 
 to proof. They are to be carefully made, and duly recorded and reported to the Bureau with 
 the other proofs and inspections, that they may afford means of comparison between the metal 
 of different foundries and guns. 
 
 No particular value is attached to these tests as an indication of the endurance of the gun, 
 but only as exhibiting the similarity that the several guns bear to the standard gun. Experi- 
 ence has shown that a variation of 2,250 pounds, more or less, in the tensile strength, is a 
 sufficient limit to be allowed, and within which to confine the founders; an exact adherence 
 being impossible. 
 
 THE INSTRUMENTS employed in TESTING METALS are as follows : 
 
 THE TESTING MACHINE, (devised by Major W. Wade,) complete with the implements for 
 determining the resistance offered by various kinds of metal to tensile, torsional, transverse, 
 bursting, crushing, and indenting forces. 
 
 THE HYDROMETER, (constructed on the principle of Nicholson's, and improved by Wade,) 
 complete with implements and adjusting weight for the determination of the density of samples.* 
 
 The elaborate "Reports of Experiments on the Strength and other Properties of Metal for 
 Cannon," published in 1856, by authority of the Secretary of War, contains full descriptions 
 of these instruments, and their implements, with plates. A copy of this work will be furnished 
 for the use of the inspecting officer at each of the foundries. 
 
 WURDEMAN'S DENSIMETER, or balance for specific gravities. 
 2 
 
10 
 
 DETERMINATION OF DENSITY AND TENACITY. 
 
 DENSITY. 
 
 To determine the density, the sample is weighed in air, and in pure distilled water. Clear 
 rain or river water may he substituted, if its relative density be first accurately determined. 
 The hydrometer may be employed for this purpose, and the proper correction applied. 
 
 The weight of the hydrometer, together with its balance weight in distilled water, deter- 
 mines the weight of a quantity of standard water equal in bulk to the immersed part of the 
 instrument. 
 
 The weight of the hydrometer and its load, when immersed in like manner, in any other 
 water at the same temperature, determines the weight of a corresponding bulk of the latter ; 
 and this weight, divided by the former, gives the multiplier for correcting the density, when 
 ascertained in any other than distilled water. 
 
 At the foundries, generally, river water is found to be sufficiently pure for use, without 
 requiring any correction. 
 
 In determining the density of samples, first load the weight-dish with the grain weights, 
 until the hydrometer is immersed to its zero mark, and then record the sum of the w'eights in 
 the dish as the balance of the hydrometer. Next remove the weights, and place the sample in the . 
 dish with as many weights as will bring the hydrometer again to its zero point, and record the 
 sum of these weights as the balance with the sample in air. The difference between these 
 balances is the weight of the sample in air. Then place the sample on the bulb, and immerse 
 both, until the hydrometer is again adjusted to its zero, and then record the weights employed 
 in this adjustment as the balance with the sample in water. The difference between this balance 
 and that given by the sample in air is the weight of water displaced by the immersed sample. 
 lu this operation, care must be taken to remove any air bubbles, which is facilitated by first 
 wetting the specimen. 
 
 The temperature of the water at the time of weighing the immersed sample is observed 
 and noted by means of a thermometer suspended in it. If it is not at 60, the weight of water 
 displaced by the sample is divided by the tabular number opposite the noted temperature, 
 and the quotient gives the corrected displacement. The weight of the sample in air, divided 
 by the corrected displacement, gives the density of the sample. 
 
 EXAMPLE. 
 
 Sample No. 4 H, from gun head : 
 
 Balance of the hydrometer 11485.0 
 
 Balance with sample in air 923.0 
 
 Difference = weight of sample in air 10562.0 
 
11 
 
 Balance with sample in water 2370.4 
 
 Balance with sample in air 923.0 
 
 Difference = weight of water displaced : noted temperature, 72 J 1447.4 
 
 Tabular number 72 J= .998912 
 Then 1447.4 
 
 = 1449.0 = corrected displacement 
 
 .998912 
 And 10562 
 
 =7.289 = density. 
 
 1449 
 
 Or by logarithms : 
 
 Logarithm*. 
 
 Water displaced at 72J = 1447.4 3.1C05886 
 
 Tabular number for 72J = .998912 I 9995274 
 
 Logarithm of corrected displacement 3.1610612 
 
 Weight of sample in air= 10562 4.0237461 
 
 Corrected displacement 3.1610612 
 
 Density = 7.289 = 0.8626849 
 
 If impure water has been used, correct the ascertained density by the rule given in the 
 last paragraph. 
 
 The determination of densities by the hydrometer, (or hydrostatic balance,) although 
 theoretically exact, requires much practice to arrive at correct results, and is moreover very 
 tedious. 
 
 The densimeter, or balance, may therefore be advantageously substituted for it, the results 
 being occasionally checked by the hydrometer. 
 
12 
 
 Weights of distilled water displaced ly the same glass bulb at different temperatures, compiled by W. Wade from Uasslcr'i 
 
 report on weights and measures. 
 
 Tempera- 
 ture, Fahr. 
 
 Weight of water 
 reduced to an unit. 
 
 Logarithms of 
 weights. 
 
 Tempera- 
 ture, Fahr. 
 
 Weight of water 
 reduced to an unit. 
 
 Logarithms of 
 weights. 
 
 Tempera- 
 ture, Fahr. 
 
 Weight of water 
 reduced to an unit. 
 
 Logarithms of 
 weights. 
 
 o 
 
 
 
 o 
 
 
 
 o 
 
 
 
 32.00 
 
 1. 000395 
 
 0. 0001706 
 
 45. 00 
 
 1. 000621 
 
 0. 0002699 
 
 58.00 
 
 1.000133 
 
 0. 0000579 
 
 .25 
 
 406 
 
 . 0001764 
 
 .25 
 
 619 
 
 . 0002687 
 
 .25 
 
 118 
 
 . 0000512 
 
 .50 
 
 420 
 
 .0001825 
 
 .50 
 
 616 
 
 . 0002675 
 
 .50 
 
 101 
 
 . 0000439 
 
 .75 
 
 433 
 
 .0001880 
 
 .75 
 
 613 
 
 . 0002660 
 
 .75 
 
 085 
 
 .0000368 
 
 33.00 
 
 444 
 
 . 0001928 
 
 46.00 
 
 610 
 
 .0002646 
 
 59.00 
 
 068 
 
 . 0000296 
 
 .25 
 
 455 
 
 . 0001975 
 
 .25 
 
 606 
 
 . 0002631 
 
 .25 
 
 051 
 
 .0000222 
 
 .50 
 
 467 
 
 . 0002028 
 
 .50 
 
 602 
 
 .0002615 
 
 .50 
 
 034 
 
 . 0000149 
 
 .75 
 
 479 
 
 .0002078 
 
 .75 
 
 598 
 
 . 0002598 
 
 .75 
 
 017 
 
 . 0000072 
 
 34.00 
 
 489 
 
 . 0002123 
 
 47.00 
 
 594 
 
 . 0002578 
 
 60.00 
 
 1.000000 
 
 0. 0000000 
 
 .25 
 
 499 
 
 .0002167 
 
 .25 
 
 589 
 
 . 0002558 
 
 .25 
 
 0. 999981 
 
 1.9999919 
 
 .50 
 
 510 
 
 . 0002214 
 
 .50 
 
 584 
 
 . 0002537 
 
 .50 
 
 963 
 
 .9999839 
 
 .75 
 
 519 
 
 . 0002253 
 
 .75 
 
 579 
 
 . 0002515 
 
 .75 
 
 945 
 
 .9999760 
 
 35.00 
 
 527 
 
 . 0002288 
 
 48.00 
 
 574 
 
 . 0002493 
 
 61.00 
 
 927 
 
 .9999681 
 
 .25 
 
 536 
 
 . 0002329 
 
 .25 
 
 569 
 
 . 0002470 
 
 .25 
 
 909 
 
 .9999603 
 
 .50 
 
 545 
 
 . 0002366 
 
 .50 
 
 564 
 
 . 0002448 
 
 .50 
 
 890 
 
 .9999522 
 
 .75 
 
 553 
 
 . 0002401 
 
 .75 
 
 558 
 
 . 0002421 
 
 .75 
 
 871 
 
 .9999440 
 
 36.00 
 
 560 
 
 . 0002432 
 
 49.00 
 
 551 
 
 .0002393 
 
 62.00 
 
 853 
 
 .9999361 
 
 .25 
 
 566 
 
 . 0002459 
 
 .25 
 
 545 
 
 . 0002366 
 
 .25 
 
 834 
 
 . 9999280 
 
 .50 
 
 572 
 
 . 0002463 
 
 .50 
 
 538 
 
 .0002336 
 
 .50 
 
 814 
 
 .9999193 
 
 .75 
 
 577 
 
 . 0002504 
 
 .75 
 
 531 
 
 . 0002306 
 
 .75 
 
 795 
 
 . 9999108 
 
 37.00 
 
 581 
 
 . 0002523 
 
 50.00 
 
 524 
 
 . 0002276 
 
 63.00 
 
 774 
 
 .9999020 
 
 .25 
 
 586 
 
 . 0002542 
 
 .25 
 
 517 
 
 . 0002244 
 
 .25 
 
 753 
 
 . 9998929 
 
 .50 
 
 589 
 
 . 0002561 
 
 .50 
 
 508 
 
 .0002207 
 
 .50 
 
 733 
 
 . 9998840 
 
 .75 
 
 595 
 
 . 0002581 
 
 .75 
 
 499 
 
 . 0002168 
 
 .75 
 
 712 
 
 . 9998747 
 
 38.00 
 
 599 
 
 . 0002603 
 
 51.00 
 
 490 
 
 . 0002130 
 
 64.00 
 
 692 
 
 .9998660 
 
 .25 
 
 604 
 
 . 0002622 
 
 .25 
 
 482 
 
 . 0002191 
 
 .25 
 
 672 
 
 . 9998574 
 
 .50 
 
 609 
 
 .0002642 
 
 .50 
 
 472 
 
 . 0002050 
 
 .50 
 
 651 
 
 . 9998483 
 
 .75 
 
 614 
 
 .0002666 
 
 .75 
 
 462 
 
 . 0002007 
 
 .75 
 
 629 
 
 . 9998388 
 
 39.00 
 
 619 
 
 . 0002685 
 
 52.00 
 
 452 
 
 . 0001961 
 
 65.00 
 
 608 
 
 .9998294 
 
 .25 
 
 628 
 
 . 0002725 
 
 .25 
 
 441 
 
 . 0001915 
 
 .25 
 
 585 
 
 .9998198 
 
 .50. 
 
 635 
 
 .0002755 
 
 .50 
 
 430 
 
 . 0001869 
 
 .50 
 
 563 
 
 .9998104 
 
 .75 
 
 642 
 
 .0002786 
 
 .75 
 
 419 
 
 . 0001821 
 
 .75 
 
 542 
 
 .9998011 
 
 40.00 
 
 646 
 
 . 0002806 
 
 53.00 
 
 409 
 
 . 0001775 
 
 66.00 
 
 521 
 
 . 9997918 
 
 .25 
 
 649 
 
 . 0002817 
 
 .25 
 
 398 
 
 . 0001727 
 
 .25 
 
 499 
 
 .9997822 
 
 .50 
 
 650 
 
 . 0002821 
 
 .50 
 
 387 
 
 . 0001679 
 
 .50 
 
 479 
 
 .9997737 
 
 .75 
 
 650 
 
 . 0002821 
 
 .75 
 
 374 
 
 . 0001625 
 
 .75 
 
 454 
 
 .9997630 
 
 41.00 
 
 649 
 
 . 0002819 
 
 54.00 
 
 363 
 
 . 0001574 
 
 67.00 
 
 432 
 
 .9997533 
 
 .25 
 
 649 
 
 . 0002815 
 
 .25 
 
 349 
 
 . 0001515 
 
 .25 
 
 409 
 
 .9997435 
 
 .50 
 
 647 
 
 . 0002810 
 
 .50 
 
 337 
 
 . 0001465 
 
 .50 
 
 387 
 
 . 9997338 
 
 .75 
 
 645 
 
 .0002802 
 
 .75 
 
 322 
 
 .0001398 
 
 .75 
 
 365 
 
 .9997243 
 
 42.00 
 
 644 
 
 .0002796 
 
 55.00 
 
 307 
 
 .0001348 
 
 68.00 
 
 343 
 
 .9997146 
 
 .25 
 
 643 
 
 .0002792 
 
 .25 
 
 296 
 
 . 0001286 
 
 .25 
 
 320 
 
 . 9997047 
 
 .50 
 
 642 
 
 .0002787 
 
 .50 
 
 282 
 
 . 0001223 
 
 .50 
 
 297 
 
 .9996945 
 
 .75 
 
 641 
 
 .0002781 
 
 .75 
 
 267 
 
 . 0001161 
 
 .75 
 
 273 
 
 .9996843 
 
 43.00 
 
 639 
 
 . 0002774 
 
 56.00 
 
 254 
 
 . 0001103 
 
 69.00 
 
 249 
 
 .9996740 
 
 .25 
 
 637 
 
 .0002766 
 
 .25 
 
 239 
 
 . 0001040 
 
 .25 
 
 226 
 
 .9996636 
 
 .50 
 
 ea5 
 
 . 0002756 
 
 .50 
 
 224 
 
 . 0000973 
 
 .50 
 
 202 
 
 .9996532 
 
 .75 
 
 633 
 
 . 0002748 
 
 .75 
 
 209 
 
 . 0000910 
 
 .75 
 
 178 
 
 .9996427 
 
 44.00 
 
 631 
 
 . 0002740 
 
 57.00 
 
 195 
 
 . 0000846 
 
 70.00 
 
 153 
 
 . 9996320 
 
 .25 
 
 629 
 
 .0002731 
 
 .25 
 
 181 
 
 . 0000783 
 
 .25 
 
 127 
 
 . 9996208 
 
 .50 
 
 626 
 
 . 0002721 
 
 .50 
 
 165 
 
 . 0000717 
 
 .50 
 
 102 
 
 .9996098 
 
 .75 
 
 1.000624 
 
 0. 0002710 
 
 .75 
 
 1.000148 
 
 0. 0000644 
 
 .75 
 
 0.999076 
 
 T. 9995985 
 
13 
 
 of diitilltd trattr diiplaetd by the lamt glati knit at diftreut temptraturti, l(c. Continued. 
 
 b 
 
 Weight of wa- 
 ter reduced 
 to an unit. 
 
 }! 
 
 Temperature, 
 Fahr. 
 
 Weipht of wa- 
 ter reduced 
 to an unit 
 
 o 
 
 1* 
 
 f * 
 
 Temperature, 
 Fahr. 
 
 Weipht of wa- 
 ter reduced 
 to an unit. 
 
 "3 
 
 Is 
 
 It 
 J 
 
 o 
 
 
 
 o 
 
 
 
 o 
 
 
 
 71.00 
 
 0.999050 
 
 1.9995873 
 
 76.25 
 
 0.998430 
 
 ~1. 9993175 
 
 81.50 
 
 0.997754 
 
 "1.9990233 
 
 .as 
 
 024 
 
 .9995759 
 
 .50 
 
 399 
 
 .9993039 
 
 .75 
 
 718 
 
 .9990079 
 
 .50 
 
 0.986907 
 
 .9995648 
 
 .75 
 
 367 
 
 .9992904 
 
 82.00 
 
 681 
 
 .9989918 
 
 .75 
 
 969 
 
 .9996588 
 
 77.00 
 
 337 
 
 .9992771 
 
 .85 
 
 644 
 
 .9989756 
 
 78.00 
 
 942 
 
 .9995401 
 
 .85 
 
 309 
 
 .9992649 
 
 .50 
 
 607 
 
 .9989596 
 
 .35 
 
 912 
 
 .9995274 
 
 .50 
 
 278 
 
 .9992515 
 
 .75 
 
 571 
 
 JBKM:!.* 
 
 .50 
 
 884 
 
 .9995150 
 
 .75 
 
 848 
 
 .9992382 
 
 83.00 
 
 536 
 
 .9989286 
 
 .75 
 
 855 
 
 .9996027 
 
 78.00 
 
 216 
 
 .9992244 
 
 .85 
 
 500 
 
 .9989138 
 
 73.00 
 
 -.'.-. 
 
 .9994892 
 
 .85 
 
 184 
 
 .9992104 
 
 .50 
 
 468 
 
 .9988969 
 
 .85 
 
 795 
 
 .9994765 
 
 .50 
 
 152 
 
 .9991965 
 
 .76 
 
 433 
 
 .9988837 
 
 .50 
 
 766 
 
 .9994635 
 
 .75 
 
 120 
 
 .9991836 
 
 -4. IN' 
 
 398 
 
 .9988684 
 
 .75 
 
 736 
 
 .9994506 
 
 79.00 
 
 088 
 
 .9991686 
 
 .25 
 
 363 
 
 .9988532 
 
 74.00 
 
 705 
 
 .9994373 
 
 .25 
 
 055 
 
 .9991545 
 
 .50 
 
 327 
 
 .9988378 
 
 .85 
 
 675 
 
 .9994241 
 
 .50 
 
 022 
 
 .9991400 
 
 .75 
 
 292 
 
 .9988223 
 
 .50 
 
 645 
 
 .9994113 
 
 .75 
 
 0.997989 
 
 .9991258 
 
 85.00 
 
 256 
 
 .9988068 
 
 .75 
 
 615 
 
 .9993979 
 
 80.00 
 
 956 
 
 .9991113 
 
 .25 
 
 220 
 
 .9987908 
 
 75.00 
 
 584 
 
 .9993845 
 
 .25 
 
 923 
 
 .9990970 
 
 .50 
 
 183 
 
 .9987750 
 
 .85 
 
 553 
 
 .9993710 
 
 .50 
 
 889 
 
 .9990822 
 
 .75 
 
 150 
 
 .9987604 
 
 .50 
 
 521 
 
 .9993574 
 
 .75 
 
 855 
 
 .9990673 
 
 86.00 
 
 0.997116 
 
 1.9987456 
 
 .75 
 
 492 
 
 .9993440 
 
 81.00 
 
 821 
 
 .9990526 
 
 
 
 
 76.00 
 
 0.996461 
 
 1.9993313 
 
 .25 
 
 0.997788 
 
 1.9990383 
 
 
 
 
 To make the corrections for the weight of water displaced when the body is weighed at any 
 other temperature than (TO , divide the ascertained displacement by that number in the table 
 which corresponds with the noted temperature, and the quotient will be the weight of water 
 which the same body would have displaced in the same water if weighed at the temperature 
 of 60. Or by logarithms, subtract the logarithm opposite the noted temperature from the 
 ascertained logarithm of displacement, and the remainder will be the logarithm of the corrected 
 displacement. The volume of the body weighed changes with variations of temperature, and 
 this will cause a slight error when the weighings are made at extremes of temperature. But 
 as the difference between the dilatation by heat of the glass bulb and cast-iron cannot bo 
 measured, error from this cause may be neglected. 
 
 The temperature of 60 Fahrenheit has been taken as the nnit, because that is about the 
 medium temperature which occurs in ordinary practice. 
 
14 
 
 WURDEMAN'S DENSIMETER, OR BALANCE FOR SPECIFIC GRAVITIES. 
 
 DESCRIPTION. 
 
 The balance for the determination of specific gravities is in principle a simple beam 
 scale of accurate workmanship. 
 
 As made by Wurdeman, it consists of an open beam of German silver, twelve and nine 
 tenths (12^,) inches in length between the knife edges; one and three fourths (1|) inches in 
 width at the centre; three fourths (|) of an inch at the extremities of the beam; and two 
 tenths ( T 2 ) of an inch in thickness. 
 
 From the extremities of the beam the scale pans are suspended on knife edges. 
 
 The knife edge, in the centre of the beam, is one and four tenths (! T *o) inches long; those 
 at the extremities nine tenths (y 9 ,) of an inch; all bearing their lengths on steel plates, which 
 are preferable to stones, as the latter are seldom of sufficient uniformity in texture to give, in 
 cutting and polishing a perfectly' plain surface. 
 
 The beam is supported on a hollow column, through which a rod passes for lifting the beam, 
 which, when not in use, rests on its Y's on a cross-bar at the top of the column; this bar also 
 supports the scale pans on separate rests, free from contact with the knife edges. 
 
 The column is set on a brass plate, furnished with a circular spirit level and foot screws 
 for accurately levelling it. 
 
 The whole apparatus is enclosed in a glass case, to protect it from dust or currents of air, 
 with a sliding front, which is counterpoised for convenient manipulation. 
 
 ADJUSTMENTS. 
 
 The beam is balanced by two adjustments placed above it: Firstly, by the horizontal 
 screws, with milled heads, for the zero of the index below; and, secondly, by the large nut on 
 the perpendicular screw for vertical balance. This last, when once set, it is seldom necessary 
 to touch. 
 
 To adjust the arms to equal length: There is to each knife-edge end a steel screw, with 
 <C~ capstan head, which, when screwed forward, will spring out the part on which the knife edge 
 rests, and thus lengthen its distance from the centre. Both ends are made thus adjustable, by 
 which means perfect symmetry of the two parts of the beam is obtained, and the necessity of 
 screwing back during the adjustment is obviated, since it will merely be necessary to lengthen 
 the arm which proves to be shortest. 
 
 To test this, the relative place of the scales should be changed after first balancing them 
 exactly; if, after the change, either preponderates, it proves that arm to be the longest. One 
 half the difference is to be corrected with weights, and the other half with the adjusting screws. 
 Great caution must, however, be observed in not screwing up too much at a time. 
 
 A correct result in weighing may be obtained without this adjustment being absolutely 
 exact, by first balancing the specimen to be weighed with any convenient substance, then re- 
 moving the specimen and substituting in its place known weights until equilibrium with the 
 counterpoise is restored. 
 
15 
 
 / USE OP THE INSTRUMENT. 
 
 By a crank placed in front of the case, the centre bearing is gently raised, which, lifting 
 the beam off its Y's, also takes up the scales. 
 
 When the beam is completely raised, the oscillations of the scales are arrested by touching 
 the spring lever on the right of the crank. On abandoning the lever the preponderance of 
 the specimen, or the weight, will immediately be manifested, and additional weights may be 
 added or removed until they are in equilibrium. 
 
 When placing the specimen and estimated counterbalancing weights in the scales, the beam 
 should always be let down on the supports; but small weights may be added or changed whilst 
 simply arresting the scales with the lever. 
 
 The door should not be pushed up higher than is just necessary to obtain convenient access. 
 
 As the balance is very sensitive, care should be taken not to abrade the pans by carelessly 
 putting in the specimens, or rubbing to remove dust. . 
 
 DETERMINATION OF SPECIFIC GRAVITY. ^ 
 
 For the determination of specific gravities a German silver vessel is used, just large enough 
 to conveniently hold the specimen, and open at the top, which is planed off perfectly straight, 
 so that a plate-glass, provided for the purpose, can be slid over it, and will shut air-tight. 
 This vessel is filled with distilled water, carefully removing air bubbles from inside the vessel, 
 or drops mechanically adhering to the outside. Weight and temperature are noted, and a 
 table may be computed, so that this element constitutes, for the instrument used, a constant. 
 It will be convenient to keep the water in a reservoir of considerable size, to avoid the incon- 
 venience of frequent changes of temperature. 
 
 The absolute weight of the specimen having been previously taken and noted, the specimen 
 is then submerged in the vessel, and displaces a quantity of water equal to its volume. The 
 vessel is again covered with the plate-glass, using the same precautions as above, and the 
 weight is taken. 
 
 Since specific gravity is represented by the ratio of the absolute weights of the same 
 volume of water, and of the article to be determined, we have to divide the weight of specimen 
 by a quantity obtained, by deducting the weight of the vessel, with specimen inserted, from 
 the sum of weight of vessel filled with water, aud of the weight of specimen. 
 
 Therefore, if 
 
 = Weight of vessel filled with water (constant); 
 W = Absolute weight of specimen; 
 Wi = Weight of vessel with specimen submerged ; 
 8 = Specific gravity; 
 
 We have 
 
 8 _ _W _ 
 
 \V-\V, 
 
16 
 
 BY DENSIMETER. 
 
 FORM OF EECORD OF COMPUTATION, 
 
 Fort Pitt Foundry, 
 
 Calibre. 
 
 No. 
 
 Spec. 
 
 Temp 
 
 Weight. 
 
 Grains. 
 
 Grains. 
 
 Temp. 
 
 Log. 
 
 8p. Gr. 
 
 
 1910 
 
 H. 1 
 
 63 
 
 Tank filled 
 
 8962 1 ) 
 
 
 63 
 
 1 9999020 ) 
 
 
 
 
 
 
 Spec, in air 
 
 9845 5 \ 
 
 18807 6 
 
 
 3 9932378 \ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 17465 
 
 
 3 9931398 
 
 
 
 
 
 
 Water displaced . 
 
 
 1342 6 
 
 
 3 1279466 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 8651932 
 
 7.332 
 
 IX-inch 
 
 1910 
 
 H. 2 
 
 63 
 
 
 8962. 1 > 
 
 
 63 
 
 1 9999020 ^ 
 
 
 
 
 
 
 
 9787.2J 
 
 18749. 3 
 
 
 3. 9906585 ) 
 
 
 
 
 
 
 
 
 17416. 5 
 1332. 8 
 
 
 3. 9905605 
 3 1247650 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 8657955 
 
 7.342 
 
 
 1910 
 
 H. 3 
 
 63 
 
 
 8962. 1 ) 
 
 
 63 
 
 1 9999020 \ 
 
 
 
 
 
 
 
 9899. 6 J 
 
 18861.7 
 
 
 3. 9956176 ] 
 
 
 
 
 
 
 
 
 17513. 5 
 1348.2 
 
 
 3. 9955196 
 3. 1297543 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8657653 
 
 7.341 
 
 IX-inch shell gun . . 
 
 1912 
 
 H.I 
 
 63 
 
 
 8962.1 > 
 9872. 5 5 
 
 18834.6 
 
 63 
 
 1. 9999020 ? 
 3.9944271 $ 
 
 
 
 
 
 
 
 
 17487.2 
 1347 4 
 
 
 3. 9943291 
 3 1294965 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 86483-26 
 
 7.325 
 
 IX-inch 
 
 1912 
 
 H. 2 
 
 63 
 
 
 8962.1 ) 
 
 
 63 
 
 1.9999020 ) 
 
 
 
 
 
 
 
 9846. 6 5 
 
 18808,7 
 
 
 3. 9932863 $ 
 
 
 
 
 
 
 
 
 17467. 3 
 1341 4 
 
 
 3.9931883 
 3 1275583 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 8656300 
 
 7.339 
 
 IX-inch 
 
 1912 
 
 H. 3 
 
 63 
 
 
 8962. 1 ) 
 
 
 63 
 
 1. 9999020 \ 
 
 
 
 
 
 
 
 9724 ) 
 
 18686 1 
 
 
 3. 9878450 $ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 17361 3 
 
 
 3. 9877470 
 
 
 
 
 
 
 
 
 1324 8 
 
 
 3. 1221503 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 8655967 
 
 7.338 
 
 FORM OF 
 
 Report of the density and tensile strength of the specimens taken 
 
 Calibre. 
 
 Foundry 
 mark. 
 
 Specimen. 
 
 Temp. 
 
 tank. 
 
 Density hy 
 densimeter. 
 
 Temp, 
 hydro. 
 
 Density by 
 hydro. 
 
 Diff. of 
 temp. 
 
 
 No. 1910 
 
 H. 1 
 
 63 
 
 7.332 
 
 64 
 
 7.330 
 
 1 
 
 
 1910 
 
 H 2 
 
 63 
 
 7 342 
 
 
 7.341 
 
 
 
 1910 
 
 H 3 
 
 63 
 
 7 341 
 
 
 7.340 
 
 
 
 No. 1912 
 
 H. 1 
 
 63 
 
 7.325 
 
 64 
 
 7.324 
 
 1 
 
 
 1912 
 
 H 2 
 
 63 
 
 7 339 
 
 
 7.338 
 
 
 
 1912 
 
 H 3 
 
 63 
 
 7 338 
 
 
 7.340 
 
 
 
 
 
 
 
 
 
 
17 
 
 ORDNANCE-YARD, WASHINGTON. 
 Atacmfor 19, 1863. 
 
 BY HYDROMETER. 
 
 Calibre. 
 
 No. 
 
 Spec. 
 
 'emp. 
 
 Weight. 
 
 Grains. 
 
 (ilains. 
 
 
 Log. 
 
 8p. Or. 
 
 
 1910 
 
 H 1 
 
 64 
 
 Bal. of hyd 
 
 12784. 2 ) 
 
 
 64 
 
 1.9998660 ) 
 
 
 
 
 
 
 Bal. with spec, in air 
 
 2938.5$ 
 
 '.M.i. . 
 
 
 3.9932466$ 
 
 
 
 
 
 
 Spec, in water 
 
 4281.3 
 
 1342.8 
 
 
 3.9931126 
 3.1280113 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8651013 
 
 7.330 
 
 IX.i nc h 
 
 1910 
 
 H. 2 
 
 64 
 
 
 12784. 2 ) 
 
 
 64 
 
 
 
 
 
 
 
 
 2996.7 $ 
 
 
 
 3. 9906718 $ 
 
 
 
 
 
 
 
 4329.6 
 
 1332 9 
 
 
 3. 99U537H 
 3 1247976 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8657402 
 
 7.341 
 
 IX-inch 
 
 1910 
 
 H. 3 
 
 64 
 
 
 12784.2? 
 
 
 64 
 
 1.9998660) 
 
 
 
 
 
 
 
 2884.7 $ 
 
 
 
 3.9956133$ 
 
 
 
 
 
 
 Water displaced 
 
 4332.9 
 
 1348 2 
 
 
 3. 99M793 
 3. 1297543 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8657250 
 
 7.340 
 
 IX-inch 
 
 1912 
 
 H. 1 
 
 64 
 
 
 12784.2) 
 
 
 64 
 
 1.9998660 ) 
 
 
 
 
 
 
 
 2911.8J 
 
 9872.4 
 
 
 3. 9944227 $ 
 
 
 
 
 
 
 Water displaced 
 
 4259.4 
 
 1347 6 
 
 
 3. 99428*7 
 3 1295610 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8647277 
 
 7.324 
 
 IX-inch 
 
 1912 
 
 H. 2 
 
 64 
 
 
 12784. 2 ? 
 
 
 64 
 
 1.9998660 ) 
 
 
 
 
 
 
 
 2937.8$ 
 
 9846.4 
 
 
 3. 9932775 $ 
 
 
 
 
 
 
 
 45279.2 
 
 '1341.4 
 
 
 3.9931435 
 3 1275583 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8655852 
 
 7.338 
 
 IX-inch 
 
 1912 
 
 H.3 
 
 64 
 
 
 12784.2 1 
 
 
 64 
 
 1 9998660 ( 
 
 
 
 
 
 
 
 3060.2 | 
 
 9724.0 
 
 
 3.9878450$ 
 
 
 
 
 
 
 Water displaced .. 
 
 4384.6 
 
 1324 4 
 
 
 3.9877110 
 3 1220192 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .8656918 
 
 7.340 
 
 REPORT. 
 
 from the following cannon, Fort Pitt Foundry, Pitt-tburg, Pa. 
 
 Actual density. 
 
 Mean density. 
 
 Ilium, of 
 specimen. 
 
 Breaking weight. 
 
 Tensile strength. 
 
 Mean tent. str. 
 
 Date, when received, Ac. 
 
 7.331 
 
 r.M 
 
 7.341 
 7.326 
 7.330 
 7.339 
 
 
 7.338 
 7.334 
 
 1.20 
 1.20 
 
 Pound$. 
 SfHMK) 
 390(10 
 %NXN) 
 S7700 
 37800 
 
 asm 
 
 1'nanils. 
 
 am 
 
 3448(1 
 
 .:\\-> 
 
 :m.\n 
 
 ::.:i-.' 
 33600 
 
 
 34187 
 
 MM 
 
 Received November 19, 1863. 
 Broken November 24, 1863. 
 
 3 
 
18 
 
 TENACITY. 
 
 After the density is ascertained, and before the sample is inserted in the pincers for the 
 tensile test, its smallest diameter in the middle is accurately measured by the specimen calipers, 
 and recorded. The breaking weight is divided by the area of its smallest diameter, and the 
 quotient gives the tenacity, or the strength per square inch. 
 
 In order to obtain reliable comparative results, it is necessary that the specimens shall all conform to the 
 standard in size and shape ; 
 
 The breaking strain be applied slowly and gradually; 
 
 That the specimen he placed fairly in the clamps, so that it is not subjected to a strain of torsion with 
 that of extension. 
 
 EXAMPLE. 
 
 Sample No. 4 H, from gun head : 
 
 Breaking weight, 50500 
 
 Diameter, 1.25. Area, 1.22719 , 
 
 Logarithms. 
 4.7032914 
 0889099 
 
 Tenacity, or strength per square inch, 41151 pounds 4.6143815 
 
 The following table contains the areas and the logarithms for all the variations of diameter 
 likely to occur in tensile samples: 
 
 Diam. 
 
 Area. 
 
 Logarithms. 
 
 Diam. 
 
 Area. 
 
 Logarithms. 
 
 Diam. 
 
 Area. 
 
 Logarithms. 
 
 1.190 
 
 1. 11220 
 
 . 0461839 
 
 1.204 
 
 1. 13853 
 
 . 0563429 
 
 1.297 
 
 1.32120 
 
 . 1209698 
 
 1.191 
 
 1.11407 
 
 .0469135 
 
 1.205 
 
 1. 14042 
 
 . 0570639 
 
 1.298 
 
 1.32324 
 
 . 1216393 
 
 3.192 
 
 1.11594 
 
 . 0476425 
 
 1.206 
 
 1. 14231 
 
 . 0577845 
 
 1.299 
 
 1. 32528 
 
 . 1223083 
 
 1.193 
 
 1. 11782 
 
 . 0483707 
 
 1.207 
 
 1. 14421 
 
 . 0585045 
 
 1.300 
 
 1. 32732 
 
 . 1229767 
 
 1.194 
 
 .11969 
 
 . 0490985 
 
 1.208 
 
 1.14610 
 
 . 0592237 
 
 1.301 
 
 1.32937 
 
 . 1236446 
 
 1.195 
 
 . 12157 
 
 . 0498257 
 
 1.209 
 
 1. 14800 
 
 . 0599425 
 
 1.302 
 
 1.33141 
 
 . 1243120 
 
 1.196 
 
 . 12345 
 
 . 0505523 
 
 1.210 
 
 1. 14990 
 
 .0606607 
 
 1.303 
 
 1.33346 
 
 . 1249788 
 
 1.197 
 
 . 12533 
 
 . 0512783 
 
 1.290 
 
 1. 30698 
 
 . 1162693 
 
 1.304 
 
 1.33550 
 
 . 1256451 
 
 1.198 
 
 . 12721 
 
 . 0520035 
 
 1.291 
 
 1. 30901 
 
 . 1169423 
 
 1.305 
 
 1.33755 
 
 . 1263109 
 
 1.199 
 
 . 12909 
 
 . 0527283 
 
 1.292 
 
 1.31104 
 
 .1176148 
 
 1.306 
 
 1.33960 
 
 . 1269763 
 
 1.200 
 
 . 13097 
 
 . 0534523 
 
 1.293 
 
 1.31307 
 
 . 1182868 
 
 1.307 
 
 1. 34165 
 
 . 1276411 
 
 1.201 
 
 .13286 
 
 . 0541759 
 
 1.294 
 
 1. 31510 
 
 . 1189583 
 
 1.308 
 
 1. 34370 
 
 . 1283033 
 
 1.202 
 
 .13475 
 
 . 0548989 
 
 1.295 
 
 1.31713 
 
 .1196293 
 
 1.309 
 
 1.34576 
 
 . 1289691 
 
 1.203 
 
 .13664 
 
 .0556211 
 
 1.296 
 
 1.31917 
 
 . 1202998 
 
 1.310 
 
 1. 34782 
 
 . 1296325 
 
19 
 
 INSPECTIONS OF NEW GUNS. 
 
 New guns are to be closely examined and measured, inside and out, for defects of metal or 
 manufacture, aud the results recorded in the prescribed forms by the Inspector resident at the 
 foundry, as soon after being finished as possible, if he has not already done so in the various 
 stages of manufacture, which is preferable, as the detection of errors which pass the limits of 
 toleration may save useless subsequent labor. Internal defects of metal will, for instance, 
 generally be betrayed by a close examination of the core pieces. As rust tends to conceal 
 defects, this examination of the guns is to take place before exposure to the weather. And 
 previously to the final examination and proof of guns, they are not to be covered with paint, 
 lacquer, oil, or any material which may hide defects of metal. 
 
 If it is ascertained that any attempt has been made to conceal defects, the gun or guns so 
 treated are to be rejected without further examination. 
 
 As the water-proof, which is of great importance in detecting defects of metal not other- 
 wise developed, necessarily succeeds immediately the powder-proof, and can be effectively 
 applied only in fine weather and when the temperature is above the freezing point, final inspec- 
 tions are to be made at such times only. 
 
 DESCRIPTIVE LIST OF INSTRUMENTS REQUIRED AND USED IN THE INSPECTION AND 
 
 PROOF OF GUNS. 
 
 1st. A mirror for reflecting the sun's rays into the bores. Two will be required if the sun 
 be in rear of the inspector. 
 
 2d. A lamp attached to a staff for examining the bores when the sun is obscured, or the 
 guns are under cover. 
 
 3d. A standard cylinder gauge. This is a hollow cylinder of iron, turned to the least 
 allowed diameter of the bore, and one calibre in length. It has a cross-head at each end, one 
 of which has a smooth hole through its axis to fit the staff, and the other is tapped to receive 
 the screw in the end of it. 
 
 4th. A measuring staff of steel or iron, in joints of suitable length, which are connected 
 together by screws. Each joint is provided with a light brass disc, the diameter of which ia 
 0.05 inch less than that of the bore. Through the centre of the disc there is a hole which 
 fits upon a shoulder at the joint; the whole is so arranged that when the joints are screwed 
 together the discs between them are held firmly in place, while the length of the staff is not 
 affected by them. A sled point is screwed on to the end. When pushed to the bottom of the 
 bore, the staff coincides very nearly with its axis. The outer joint is graduated to inches 
 and tenths. A slide is made to play upon it with a vernier scale, graduated to hundredths 
 of an inch. On the inner end of the slide a branch projects at a right angle, sufficiently long 
 to reach across the muzzle face, and when in contact with it to indicate the precise length 
 obtained from that point to the end of the measuring point on the other end of the staff. 
 A half disc of wood, made to fit the bore, with a groove for the staff to rest in, placed just 
 inside of the muzzle, is useful in preventing any springing of the staff. 
 
20 
 
 The point being taken off, the staff can be used with the cylinder gauge to measure the 
 distance to which the latter descends. But as the graduation is intended for the points, care 
 must be taken in this case to allow for the difference. 
 
 5th. A chamber gauge for verifying the shape and size of conical chambers. 
 
 The head should be made of close-grained, well-seasoned wood, and of the exact dimensions 
 of the chamber. Two planes crossing each other at a right angle, coinciding with the vertical 
 and horizontal central sections, have been found better than a solid block. The edges should 
 be bevelled. A metal socket in its centre connects it with the measuring staff. Being pushed 
 to the bottom of the bore, if the length coincides with that obtained by the point, it is obvious 
 that the chamber is large enough, provided the cylindrical part has not been bored too deep, 
 in which case a shoulder would be found at the junction. The edges of the gauge should be 
 chalked before it is inserted. When withdrawn, if the chalk marks are visible all around the 
 chamber, it is evident that the chamber is not too large. With slight modifications, this 
 arrangement may be applied to the slope of cylindrical chambers, and to the curve at the 
 bottom of the bore of any guns. Should the inspection of guns with conical chambers or 
 slopes take place at the foundry, an examination of the chamber reamer will be very satis- 
 factory. If found correct in size and shape, the impossibility of making the chamber too large 
 will be apparent. 
 
 6th. A star gauge, for measuring the u diameters of the bores and of cylindrical chambers. 
 This instrument is composed of the staff", the handle and a set of points for each calibre. 
 
 The staff is a brass tube, made in three pieces, for convenience of stowage, and connected 
 together, when required, by screws. Its inner end expands into a head, in which are placed 
 four steel sockets, at equal distances from each other, which receive the points. Two of the 
 sockets opposite to each other are secured permanently. The two others are movable. A 
 tapering plate or wedge, the sides of which are cylindrical, runs through a slit in the head; 
 an aperture in the inner ends of the movable socket embraces the cylinder, so that when the 
 plate is moved forward or backward, the sockets are projected or withdrawn. The tapering 
 of the plate has a certain known proportion to its length, so that if it is moved in either 
 direction a given distance, a proportional movement is imparted to the sockets, and to the 
 points which they contain. It is easy to see how, in this manner,' a movement of .10 in. 
 may increase or diminish the distance between the points .01 in. Therefore there would 
 be no difficulty in estimating, to a considerable degree of accuracy, a difference of .001 in. 
 between the points. In general, however, the distance on the plate required to move the 
 points .01 in. is about .06 in. only. 
 
 A square sliding-rod is connected with the tapering-plate, and runs through the whole 
 length of the tube, projecting some inches beyond the outer end. This rod has as many parts 
 as there are joints in the staff, and, like them, connects by screws. Bach section of the rod 
 works in its proper joint, through a square socket at each end, and is prevented from falling 
 out by pins. When screwing the joints together, if the ends of the rod are pressed up to each 
 other they become connected by the same motion. 
 
21 
 
 The staff is graduated to inches and quarters, so that the distance of the points from the 
 ninz/.le of the gun may always be known. A centre line, starting from the centre of the upper 
 socket, id marked upon the staff throughout its length. 
 
 The handle in use at present is of brass, made to fit over the outer end of the staff, and 
 to connect with the sliding-rod by a screw, having a large milled head at the outer extremity 
 of the handle. It may bo used on either joint, as required. A slit through the handle permits 
 a part of the staff near the end to be seen beneath. A scale on one side of the slit is graduated 
 with the distance that the rod moves, to throw the points .01 in. apart. 
 
 That part of the handle containing the slit and scale is separated from the other part; it 
 is made to fit closely over it. On each side there is a small tube; a thread is cut in one, through 
 which a fine screw, held by a stud on the permanent part of the handle, works and gives it 
 motion; a guide runs through the other. Seen through the slit is a small plate of silver 
 inserted in the staff, and a fine mark upon it to show the place of zero, when the points are 
 adjusted. The zero mark on the scale is made to correspond with it by means of the screw 
 just mentioned. 
 
 The points are of steel, with a strong shoulder at one end, below which the screw is cut 
 that fits into the socket in the head. A wrench is made to fit the other end so as to turn the 
 point firmly into its place. They are made of such a length that they will just pass into the 
 adjusting ring when they are all in place. To this instrument belong the adjusting 
 rings and the muzzle rest in the form of T ; of the rings there is one for each calibre, reamed 
 out to the exact minimum diameter of the bore. The latter can be used for any class of 
 gnns. Its office is to keep the staff of the star gauge in the axis of the bore. For this 
 purpose it contains a groove, above the perpendicular branch, to receive the lower half of 
 the staff. There is a movable slide on each branch, which can be adjusted to marks for 
 each calibre, so that points projecting from their rear will enter the muzzle and hold the 
 rest in place. In this position the upper edge of the transverse branch coincides with the 
 diameter of the bore. 
 
 A hook is pivoted on the innef side of the transverse branch, on one side of the groove, 
 and so fitted that when the star gauge is in the gun, it embraces one-half of that portion 
 of the staff which is above the groove. Therefore, if the transverse branch be placed so 
 as to coincide with the axis of the trunnions, the hook thrown over the staff, and the latter 
 turned so that the centre line just meets the end of the hook, the perpendicular points will 
 be perpendicular to the axis of the trunnions. If the staff is then drawn out carefully, the 
 measurements will all be taken in the same plane. A notch in the end of the hook, made to 
 coincide with the plane of the muzzle, may be used for marking the distances on the staff. 
 
 The upright branch is movable, and is made to fit into the end of the transverse branch 
 for convenience and security in packing. 
 
 In examining the bores after proof, it has been found that the greatest indentation occurs 
 in general near the seat of the projectiles. But as it is not always found at precisely the same 
 point of the circle of the bore, a convenient mode of searching for it is desirable. This ia 
 
22 
 
 supplied by a disc for circular measurements, which may also be considered as belonging to the 
 star gauge. It is made of composition, and is divided into halves, with a hole through the 
 centre to receive the staff of the star gauge. 
 
 It is turned so as to fit into the muzzle of the gun closely, with a projecting lip two or 
 three inches broad to hold it in place, and with cleats overlapping the edges, to keep it from 
 going in too far. The face is a plane surface. The circumference is divided into as many 
 equal parts as may be thought desirable, which are numbered in regular order. The centre 
 hole is reinforced on the inside by a projection which is turned to receive a collar that fits 
 closely around it, and holds the two halves together when they are placed on the staff. 
 
 When ready for use, the face is in the plane of the muzzle face. Its zero mark is made 
 to coincide with a light punch mark on the muzzle face, directly below the line of sight. 
 
 On the staff of the star gauge a brass slide is fitted, having a thumb-screw to hold it in any 
 position; from the inner end a point extends at a right angle to its axis, of sufficient length to 
 meet the points at the circumference of the disc; a centre line extends from the base to the 
 apex. The slide being moved so as to make its inner end coincide with any mark upon the 
 staff, at which a circular measurement is required, and the centre line of the point being made 
 to coincide with that of the staff, it is secured by the thumb-screw. The point of the slide is 
 then in the same plane with the perpendicular measuring points, and its direction always indi- 
 cates theirs; a series of measurements made before proof may thus be compared with another 
 made at the same points after proof. 
 
 It is obvious that the determinations will not be absolutely accurate, for when the gun is 
 worn, should the stationary points be perpendicular, the movable points being then horizontal, 
 would fall below the true horizontal diameter, and the measurements would be more in error 
 than it would be with the points in any other direction. Still, if care is taken to preserve the 
 points at the greatest length possible, a very tolerable degree of accuracy may be attained. 
 In the inspection of guns arranged on skids, the gun itself should be turned, which will ensure 
 accurate measurements. Care must also be taken not to allow the joints of the staff to be- 
 come so loose that the coincidence of the centre line is destroyed when they are screwed 
 together. If this should occur, however, a few turns of thread placed between them at the 
 time of putting the instrument together would remedy the difficulty. 
 
 7th. An instrument for verifying the interior position of vents. 
 
 When the vent is drilled in the vertical plane of the axis, as in the guns of old patterns, 
 a simple head, shaped to fit the bottom of the bore, or the chamber, with a staff fitted to it, is 
 sufficient. But for the Dahlgren guns, with two vents, some other plsfti is better. The follow- 
 ing has been found satisfactory: 
 
 A head of well seasoned wood, which is fitted to the chamber, is attached to a wooden 
 disc of the diameter of the main bore. The surface of the head corresponds with a longitudinal, 
 central section of the chamber; at the point where the projection of the vent would meet it a 
 piece of hard wood is inserted. A central line drawn through its length, crossed at a right 
 angle by another line at any known point from the smaller end, will afford convenient points 
 to measure from. A stout square wooden staff is attached to the axis of the head; at a dis- 
 
23 
 
 tanco equal to the length of the bore, the end is jogged into the centre of a half disc of wood, 
 which is fitted to. the bore. The whole is so constructed that the straight edge of the half 
 disc (or the chord) is in the same plane as a horizontal section of the head. A few holes are 
 bored through the disc attached to the half head, to allow the instrument to pass freely into 
 the pm and out of it. ^ 
 
 A wire of untempered steel of the size of the vent, with a sharp well centred point, and 
 a small spirit level, are required to use with this instrument. 
 
 The gun being levelled, and the instrument being pushed to the bottom of the bore, the 
 upper edge of the half disc near the outer end of the staff is then brought to a level. The 
 surface of the half head then corresponds with the horizontal central section of the chamber. 
 The point of the wire being pushed gently to meet it, will show very accurately the interior 
 position of the vent. 
 
 8th. Profile boards for distances in front and rear of the base line. 
 
 Their lower edges are adapted to the shape of the gun, and the upper ones are parallel 
 to the axis of the bore. 
 
 
 
 The distances from the base line of the several parts, and of the points at which diameters 
 are to be measured, are laid off accurately on the upper edge, and then marked in lines perpen- 
 dicular to it on the sides, and lower edges of the profile. A narrow strip is attached to the 
 upper edge to prevent warping, and the whole is well coated with shellac varnish to keep it 
 from absorbing moisture. 
 
 The following instruments are used in connexion with the profile boards : 
 
 A rule for verifying the marks, of such a length that not more than one fleeting may bo 
 necessary, to be graduated decimally according to the standard. 
 
 A small square of steel, to be used in referring the marks on the board to those on the 
 rule. 
 
 A steel straight-edge, long enough to extend across the muzzle-face, and several inches on 
 the board, to ascertain the extreme length from base to muzzle. It is also used for the same 
 purpose at the extreme end of the cascable. A steel scratcher, to mark the gun at points not 
 otherwise indicated, where diameters are to be measured. 
 
 9th. A trunnion square of steel or iron, for ascertaining the position of the trunnions, with 
 reference to the axis of the bore. This instrument is a square with two branches, one of 
 which is fixed and the other movable. The foot of each branch is in the same plane, and is 
 parallel to the upper edge of the main piece which connects them. The latter is graduated to 
 inches and tenths. The movable branch slides on the main piece, and may be secured to it by 
 two thumb-screws. It is provided with a vernier scale graduated to hundredths of an inch. 
 Between the branches there is a, slide,n\so provided with a vernier graduated as before, with a 
 thumb-screw to secure it firmly; in its centre there is a sliding point, moving vertically, with a 
 thumb-screw to fasten it. Above the foot of each branch there is a slit to receive the shank of 
 a plate, on the end of which a thread is cut; the lower edge of the plate forms a right angle 
 with the branch, and the plate is fastened to the branch by a nut, at a point from tlio end 
 equal to the semi-diameter of the trunnion, which is marked on each branch. 
 
24 
 
 When the feet of the branches, or the lower edge of the plates, rest upon the trunnions, 
 the upper edge of the main piece is parallel to their axis, if their alignment is correct. "When 
 in the latter position, the edges of the feet will lie close against the sides of the trunnions. 
 
 A graduated steel wedge is used to measure the deviation of the trunnions from the feet of 
 the square. 
 
 10th. A trunnion gauge, which is an iron ring of the proper diameter of the trurfnions. 
 Its outer edge coincides with the diameter of the rimbases. 
 
 llth. A trunnion rule to measure the distance of the trunnions from the base ring, or line. 
 This is an iron rod with a head at one end, through which passes one branch of a small square. 
 The centre of the rod is marked on the end, and the square is set so that the inner edge of 
 the branch which is parallel to the rod is at a distance equal to the semi-diameter of the trun- 
 nion from the centre. It is secured in this position by screws and clamps. 
 
 The upper side of the rod is graduated to inches and tenths. A slide with a slot through 
 it, to show the graduation beneath, traverses upon it, and is kept from turning by a guide on 
 the lower side. There is a vernier upon the slide graduated to hundredths of an inch; a 
 thumb-screw serves to secure the slide at any point on the rod. That end of the slide from 
 which the graduation of the rod commences has both of its sides drawn out to form knife 
 edges; the knife edges and the end of the slide are in the same plane. When the square at the 
 end is placed on the trunnion, the end of the rod will touch its side at the point of its greatest 
 diameter. The rod being held parallel to the axis of the bore, with the side of the head 
 pressing the rimbase, the knife edge will be in a proper position to fall into the base line when 
 moved to find it. 
 
 12th. A beam calliper for measuring diameters is a square of steel or iron, with two 
 branches, one of which is fixed and the other sliding. The inner edges of the two branches, 
 when pushed together, lie, of course, in contact with each other throughout their length. 
 The beam is graduated to inches and tenths. A vernier is attached to the sliding branch, 
 graduated to hundredths of an inch. The latter is provided with a thumb-screw to fasten it at 
 any point. 
 
 The length of the beam must be rather greater than the diameter; and that of the 
 branches than the semi-diameter of the guns to be inspected, at their largest points. 
 
 13th. A cascable block is a wooden cylinder of the proper diameter of the breeching hole, 
 the size of which is used to verify. 
 
 The opening between the jaws may be ascertained by measuring the iron block, which ia 
 fitted to go between them, or by a template. 
 
 14th. A vent guide, to be used with vents in guns of Dahlgren's pattern. 
 
 This instrument is made of bronze or composition. When placed upon the gun, one 
 of its branches coincides with the curve of the cylinder, and the other, starting from its centre, 
 lies along the cylinder in contact with it longitudinally. The lower edges of the branches are 
 a right" line and a curved line, making two right angles with each other. The length of that 
 of the transverse branch is equal to the distance between the centre of the two vents. The 
 rear surface of the transverse branch is curved and quadrilateral. Its sides are inclined, so 
 
25 
 
 that their rear edges show the exact direction of the vents. Every point in the upper edge 
 jies in the same horizontal plane. The height is sufficient to permit the edges to give an 
 accurate direction to the drill. 
 
 The upper edge of the other branch runs off in a sloping curve to its extremity. 
 
 A centre line is drawn through the lower edge of the longitudinal branch, and is continued 
 upwards on the rear surface of the transverse branch to the top. 
 
 The guide being placed with its centre upon the centre mark of the gun, and the centre 
 line of the longitudinal branch being made to coincide with the centre line scribed upon the 
 cylinder, the rear lower edge of the transverse branch will then coincide with the base line, ita 
 extremities will indicate the centres of the vents, and the rear edges of the sides will show 
 their true direction. 
 
 15th. Vent gauges of untempered steel wire, with shoulders to prevent them from slipping 
 into the vent. One should be of the proper'diameter of the vent, one of the greatest, and one 
 of the least diameter allowed. 
 
 16th. A vent searcher, a steel wire of the length of the vent, bent to a right angle at the 
 lower end and pointed. It is used for detecting imperfections in the sides of the vents. 
 
 17th. A semicircular protractor of metal for measuring the inclination of vents, or for 
 ascertaining their deviation from the guide. 
 
 18th. A set of templates for verifying the shape of lock-lugs, the angle of the rear sight 
 mass, the curve between the base line and the front of rear sight mass, that at the end of the 
 cascable, the bevel of the breeching hole, the opening of the cascable, the shape of the muzzle 
 swell, <tc. 
 
 If the inspection should take place at the foundry, the templates used in chipping might 
 be verified and used for inspection. 
 
 For guns of Dahlgren'a pattern, a bronze model, showing the shape of the lugs and 
 rear sight mass, and the position of the vents, has been furnished as a guide to the contractors. 
 
 19th. A standard foot-rule for verifying measures. 
 
 20th. A foot-rule of steel for measuring the masses, the length of the trunnions, and for 
 other purposes. The graduation should be extended to each end. 
 
 21st. A set of ring gauges, large, medium, and small, for inspecting the projectiles used in 
 proof. 
 
 22d. A small beam calliper, with outside edges, for examining the adjusting rings and the 
 ring gauges. 
 
 23d. A platform balance for weighing the projectiles used in proof, and for bringing the 
 shells up to the standard weight. For use with the above there should be provided a bag of 
 dry sand, a funnel, some toooden plugs for the fuze holes, and a hammer. 
 
 24th. A set of implements for loading and cleaning, viz : , 
 
 A rammer, faced with hard wood or metal, with a graduated scale on the staff, near the 
 muzzle, to show the distance of the front of the projectiles from the muzzle. 
 
 A bristle sponge with a worm in its end, for ordinary use in firing. 
 
26 
 
 A sheepskin sponge, for drying the bore after cleaning it. 
 
 A gun scraper. 
 
 A ladle. 
 
 A boring bit. 
 
 A priming wire. 
 
 A lock and laniard, should navy primers be used in firing; but if friction primers are used, 
 then a laniard with a hook in its end will be required, only. 
 
 A breeching and a couple of tackles, if the guns should be fired on skids. 
 
 pix handspikes. 
 
 Six buckets and a large tub, for washing out the guns. 
 
 And if the firing is made into a butt, then a couple of wheelbarrows, with two or three 
 pickaxes, and half a dozen shovels, will be necessary. 
 
 25th. A searcher, with six or more points, to detect injuries or cavities in the bore. 
 
 26th. A machine for taking the interior impression of vents. 
 
 This consists of a wooden head, one-half of which is cylindrical, and the other half is of 
 the shape of the chamber, both being rather smaller than the .parts of the bore that they are 
 intended for. A staff, flat on its upper side, and rounded on its under side to fit the curve of 
 the bore, is mortised into the circumference of the cylindrical part of the head. A mortise is cut 
 through the chamber part of the head, extending several inches in rear and front of the position of 
 the vent. Into this mortise a loose piece is fitted, capable of free motion upwards and downwards, 
 the top of which is fitted with holes to secure the wax or composition which is spread over its 
 surface. This movable piece rests on a wedge attached to a flat rod running through a slot in 
 the head; there is a slot in this rod about four inches long, a pin passing through it into the staff. 
 To use the instrument, withdraw the rod as far as the slot will permit, which will allow the 
 movable piece on which the composition has been spread, to drop below the surface of the head, 
 and protect it. Push the head to the bottom of the chamber, and arrange the position of the 
 staff so that the movable piece will cover the vent, then press the end of the rod home. This 
 motion will throw out the composition, and a distinct impression of the vent and of fire cracks, 
 (should there be any,) will be left upon its surface; draw the rod back as far as tbe slot will 
 allow, and withdraw the instrument: the impression, being protected thereby, will come out 
 uninjured. 
 
 Impressions of injuries or cavities in the bore may easily be taken by a similar contrivance. 
 
 27th. Hydraulic pump and apparatus for the water-proof. 
 
 Any of the various patterns of this machine may be applied to the proof of guns.' An iron 
 cross-head is secured to a stout wooden block which fits into the muzzle, and which has a flange 
 or shoulder to cover the muzzle-face ; rings of caoutchouc or gutta-percha are placed between 
 them; an iron rod with a ring in oue end, to fit over the trunnion, and with a thread cut on 
 the other end, is used on each side of the gun, to cqnnect the trunnion with the cross-head. 
 The whole is set up with nuts, and the pressure upon the rings makes a tight joint; a coupling 
 upon the cross-head receives the hose, and the water is forced into the gun through a hole in 
 
 the wooden block. Care should be taken that the valve is loaded with the proper weight for 
 
 * 
 
 proof. 
 
 28th. Dies for marking guns. A full set of figures, with such capital letters as may be 
 required for the inspection marks; these should be one inch in length. Also, small letters o 
 suitable size to mark "Ibs.," and a full set of half-inch figures. 
 
27 
 
 USE OF THE INSPECTING INSTRUMENTS. 
 
 The guns having been freed from rust, and their foundry numbers noted, in the order of 
 their relative positions, ou the field-book, the inspecting officer will proceed to verify the in- 
 struments to be used in their measurement, if this has not been previously done in a manner 
 entirely satisfactory to him. 
 
 He will then examine carefully the guns, inside and out, for defects of metal or of manu- 
 facture, and note the results. 
 
 The interior of the bore is to be examined by reflecting the rays of the sun into it from a 
 mirror or mirrors; or, if the sun is obscured awl there can be no delay, by means of a spirit-lamp, 
 or of a wax taper, on the end of a rod, taking care not to smoke the surface of the bore. 
 
 The cylinder gauge is then to be introduced, which must pass freely to the bottom of the 
 cylindrical part of the bore. If obstructed, the depth to which it reaches should be noted. 
 
 The star gauge is used to ascertain the exact diameter of the bore, and of the cylindrical 
 part of the chamber. The bore must be measured at intervals of \ inch from the bottom of 
 the cylindrical part to the seat of the shot; of 1 inch from that point to the trunnions; and of 
 5 inches from the trunnions to the muzzle. If any marks of the reamer or other defects are 
 seen in the bore, they are to be searched for, and their depths and positions noted. These 
 results are to be tabulated according to the blank forms furnished. The whole length of the bore 
 is ascertained by means of the measuring staff, with the point screwed on, supported in the 
 axis of the bore by the discs and half-lampion. 
 
 In the absence of this instrument, a pine rod, having the proper length of the bore marked 
 on it, and the end rounded fo the curve of the bottom of the bore, will answer as well, using 
 a thread or a straight-edge across the face of the muzzle. 
 
 The shape and dimensions of the chamber, and the position of the interior orifice of the vent. 
 are verified by means of the chamber gauge, the description of which will explain its use. Ar 
 inspection of the chamber reamer will be generally satisfactory in determining the size and 
 shape of the chamber. 
 
 The vent is measured by the appropriate gauges, the smaller of which must enter freely, 
 anil the larger not at all. It is searched for roughness or for cavities in the metal around it, 
 by means of the searcher, the point of which should feel every part of it carefully. 
 
 Its inclination to the surface, and its position externally, is verified by means of the vent- 
 guide furnished for the Dahlgren guns, and by the semicircular protractor and the vent-gauge. 
 
 In guns of the ordinary construction the position of the vent is marked on the profile 
 board, and its inclination to the surface is determined by the protractor and vent-gauge. 
 
 The exterior lengths of the gun are measured by the profile board, marked with/ the trne 
 dimensions, the differences being measured by the foot-rule, or, if minute, estimated by the eye. 
 
 The exterior diameters are measured with the callipers and square, or by the set-gauges used 
 in turning, and a graduated wedge. 
 
 To verify the position and alignment of the trunnions of a gun, it is first necessary to aecer- 
 
28 
 
 tain, by means of the trunnion gauge and of the callipers, their cylindrical form and their 
 diameters, which should bo the same, or allowance must be made for half the difference in 
 measuring their axial distances from the base line, by the trunnion rule, which should next 
 be done. These distances should be equal, or their axes do not coincide an error not 
 tolerated. 
 
 The trunnion square is then placed upon the trunnions in the plane of their axis. The 
 feet of its branches should coincide with the surfaces of both trunnions, throughout their length, 
 above and in rear, and their inner edges with the faces of the rimbases. Then, with the beam 
 compass, scribe on the upper surface of the gun the distance of the axis of the trunnions from 
 the base line, and push the sliding point of the square down, till, at that distance, it touches 
 the surface of the gun, and screw it fast. Then turn the gun over, and again scribe on it the 
 same distance from the base line. The square being again applied, will determine whether 
 the trunnions are above or below the axis of the bore, which will coincide with that of the gun, 
 if accurately bored and turned on the same centres and bearings. If the branches rest upon 
 the trunnions before the point of the slider touches the gun at the scribe, their axis is below; 
 but if the point touch first, above the axis of the bore, by half the space between. The 
 graduated wedge being placed under the vertical sliding point will determine the amount. If 
 both touch at once, both axes are in the same plane. 
 
 No gun can be received, the axis of the trunnions of which is above that of the bore. 
 
 The lengths of the trunnions are measured with the foot-rule, and the diameters of the 
 rimbases by that of the exterior rim of the trunnion gauge. 
 
 If the alignment of the trunnions be correct, it will serve as a means of determining the 
 correctness of the line of sight, which, before the gun is removed from the lathe, should be 
 distinctly traced on the sight-masses and the swell of the muzzle, and should be at right 
 angles to the base line, to the axes of the trunnions, and to the connecting piece of the 
 trunnion square, when its branches rest against their rear, with the plates across their upper 
 surfaces. 
 
 The Inspector will further satisfy himself of the correct tracing of the line of sight on the 
 gun by examining the lathe and the manner of tracing it in the plane of the axis of the bore, 
 at right angles to the axis of the trunnions, as by it are placed the sights and vent, and in their 
 absence it serves as a line of metal sight. 
 
 The positions of the sight-masses are verified by the profile board, and by reference to the 
 line of sight, traced on them; their form and dimensions by the templates. 
 
 The positions of the lock-lugs and their forms are verified by means of the bronze pattern 
 furnished to each foundry for each class of the Dahlgren guns, and their dimensions by the 
 templates. For other guns the position of the lock-piece is marked on the profile board, and 
 their measures taken as above. 
 
 The opening of the cascable and its curves, and those of the breech and the muzzle-swell, 
 are verified by means of the "cylinder Uoc/e" and the templates. 
 
The following variations from the proper dimensions may be tolerated by the Inspector, 
 though every effort should be made to conform exactly to the drafts furnished by the 
 Bureau of Ordnance. 
 
 Inch. 
 
 T ,. ,. A , it , f more 0.03 
 
 In the diameter of the bore . . J 
 
 ( less 0.00 
 
 f where 1 more 05 
 
 turned or planed f less ; OS 
 
 Lxtenor diameter < , 
 
 1 where not ) more 20 
 
 (_ turned or planed ) less 05 
 
 !of the bore, more or less 10 
 from rear of base ring or line to face of the muzzle, more or less .25 
 of the cascable, from rear of base ring to the end, more or less SJO 
 of the reinforce, more or less 15 
 
 From the axis of tninnions to base line, more or less 05 
 
 In the length of chamber, more or less 10 
 
 C above axis of the bore 00 
 
 In the position of the axis of the trunnions.. I , . . .. , 
 
 I below axis of the bore 20 
 
 In the length of trunnions, more or less .05 
 
 Diameter of trunnions, less 0.25 
 
 In the same gun, no variations to be tolerated in the position of the trunnions, or in their alignment. 
 
 diameter more 0.025 
 
 In the vent.. -. 
 
 do. less .000 
 
 ( more 10 
 
 In lock piece any dimensions ! 
 
 Variation of position of exterior orifice of vent 05 
 
 Idem of interior do. do 20 
 
 in the bore or vent 00 
 
 on exterior surface of reinforces, where turned or planed .10 
 
 elsewhere, where turned or planed .25 
 
 on trunnions, within one inch of rimbases .10 
 
 . on trunnions, oNcwlirrc 5 
 
 Depth of cavities . . 
 
 Enlargement or indentation of bore By proof, not to exceed 02 
 
 The measures are to be taken by scales corresponding with the standard measures of the 
 United States. 
 
 If two or more cavities should be near each other on the exterior, the gun may be rejected, 
 though the cavities should be of less depth than tolerated in the table. 
 
 If the trunnions are placed within the limits of toleration, the preponderance must not 
 vary more than 5 per cent., more or less, from that fixed in the contract. 
 
30 
 
 POWDER-PROOF. 
 
 The proof charges shall be as follows: 
 
 
 Calibre and class of g 
 
 tin. 
 
 Charge of 
 powder. 
 
 Projectile. 
 
 Wads. 
 
 Number of 
 
 fires. 
 
 
 C X V-inch 
 
 43, 000 Ibs. 
 
 Pounds. 
 56 
 
 
 SaboUi'd" 
 
 04* 
 
 
 
 
 <* 
 
 Sbett- 
 
 
 
 
 Xl-inch 
 
 16,000 Ibs. 
 
 
 
 
 j 
 
 w 
 
 
 
 "" (.15 
 
 Shell 
 
 
 10 
 
 s 
 
 
 12 500 Ibs 
 
 f!8 
 
 Solid shot 
 
 
 i 
 
 ~< 
 
 
 
 U2 
 
 Shell 
 
 
 10 
 
 J3 
 
 
 9 000 Ibs 
 
 
 
 
 1 
 
 
 
 
 UO 
 
 Shell 
 
 
 10 
 
 
 8-inch of 63 cwt., or 
 
 7,000 Ibs. 
 
 
 Shot 
 
 
 I 
 
 
 
 
 ^ UO 
 
 Shell 
 
 
 10 
 
 
 .8-inch of 55 cwt., or 
 
 6,000 Ibs. 
 
 fio 
 
 
 
 
 
 rivX. (.v-j^ 00. \ 
 
 
 \8 
 
 Shell 
 
 
 10 
 
 
 [ 130-pdr. of cwt., or 
 
 16, 000 Ibs. 
 
 30 
 
 1 shot 
 
 Gromet 
 
 10 
 
 
 64-pdr. of 106 cwt., or 
 
 12,000 Ibs. 
 
 20 
 
 do 
 
 do 
 
 10 
 
 CO 
 
 
 6,400 Ibs 
 
 15 
 
 do 
 
 do 
 
 10 
 
 ?J 
 
 32-pdr. of 51 cwt., or 
 
 5, 700 Ibs. 
 
 13 
 
 ....do 
 
 ....do 
 
 10 
 
 "o 
 
 32-pdr. of 42 cwt., or 
 
 4, 700 Ibs. 
 
 10 
 
 do 
 
 do 
 
 10 
 
 02 
 
 32-pdr of 33 cwt or 
 
 3,600 Ibs. 
 
 10 
 
 do 
 
 do 
 
 10 
 
 
 i, 32-pdr of 27 cwt., or 
 
 3,000 Ibs. 
 
 9 
 
 .. do 
 
 do 
 
 10 
 
 
 
 
 2 
 
 H 
 
 11 
 
 ID 
 
 The cannon powder for proof shall be of not less than 1,500 feet initial velocity, as 
 determined by the gun pendulum at the Ordnance yard, Washington. 
 
 It shall be filled in service cylinders, and well settled. 
 
 For chambered pieces the increased charges should fill the chamber and necessary portion 
 of the bore. 
 
 The projectiles shall be of full weight, and not below the mean gauge; the shell shall be 
 filled with a mixture of sand and ashes to bring them up to the proper weight of the filled shell. 
 
 Sabots for the shell and a gromet wad over the shot. 
 
 The gun should be fired on skids or a proving carriage, to test the trunnions. 
 
 If five per cent, out of any lot offered for ordinary proof under a contract shall fail to 
 sustain it, the whole may be rejected, as may be stipulated in the contract. 
 
 WATER-PROOF. 
 
 The pressure to be applied in the water-proof will be two atmospheres, or thirty pounds 
 to the square inch. 
 
 The penetration of water in this proof through the metal of the piece, in any place, will 
 cause the rejection of the gun; and if, on examination after the water-proof, there shall be any 
 defects indicated by weeping or dampness in the bore, the gun shall be rejected. 
 
 The water-proof is alone to be depended on to detect minute clusters of cavities in the 
 bore, which, for this purpose, should be perfectly dry, and examined by sunlight. All inspec- 
 
 * .Modified by Bureau Order of OctT 3'! L8G3, to - 
 
31 
 
 tions, consequently, should take place in fair weather, and when the temperature is above the 
 freezing point. 
 
 MARKING GDN8. 
 
 Guns for the naval service, received by authority of the Bureau of Ordnance, are to be 
 marked in the following manner, viz: 
 
 On the cylinder, in the line of sight near the sight mass, all accepted guns arc to have 
 stamped an anchor tb inches long. 
 
 Drawings of these stamps will be furnished by the Bureau of Ordnance. 
 
 On the base ring or line, the initials of the foundry, the register number, and the weight of 
 gun in pounds. 
 
 On the right trunnion, the calibre and year of fabrication. 
 
 On the left trunnion, the letter P. and the initials of the inspecting officer; all the above in 
 one-inch letters. 
 
 On the upper jaw of the cascalle, the preponderance in pounds to be stamped lightly with 
 half-inch figures. 
 
 On the end of the upper jaw, the cascable block and head of the pin, the foundry number 
 in quarter-inch figures. 
 
 The foundry number is also to be marked on the right rimbase. 
 
 Guns rejected for imperfections of any kind will have the letter C stamped on the anchor, 
 so as to partially obliterate it. 
 
 The founders are to be dissuaded from selling such guns to other parties, and required 
 to break them up. 
 
 Guns rejected for such defects as render them dangerous to those who fire them should be 
 irreparably mutilated, with the consent of the founder. 
 
 OluOJ i" 1" '" 
 
 Mivj;tll-lli:i!t.H. 
 
 X..I.- - On .ill .i|.|.n.\rd Nii\;i] duns HM- 
 
 :.l:illl|lf(l nil tin- 1-ylilliliT lir:ir tin- n 1 
 Ill tll<- I ..... Ill' Sl'jlll 
 
 _ When tin- (Inn is f., mil-mill', I lli. I. -Mi-r "' istn I 
 
32 
 
 EXTREME PROOF OF TRIAL GUNS. 
 
 The extreme proof of guns intended for trial of metal, subject to such modifications by 
 the Bureau as future experience may dictate, will be conducted as follows: 
 
 A suitable "butt" shall be erected to arrest the flight of the projectile used in proof, and 
 to admit of their easy recovery, and a bomb-proof, readily accessible, for the protection of the 
 firing party. 
 
 When practicable the "butt" should be made thick enough to allow the shot to just pass 
 through, and be stopped by another beyond it, without penetrating the latter; this is, for 
 Xl-inch, about 12 feet. 
 
 With care, it is estimated that 130 shells may be fired 1,000 times, at the rate of one 
 hundred rounds per day. 
 
 After undergoing the ordinary proof established for its calibre and class, the gun selected 
 for extreme proof shall be subjected to at least 1,000 rounds with service charges. 
 
 It may be fired from the skids, or suspended, as the Bureau may direct. 
 
 During the trial the gun shall be frequently and critically examined inside and out for 
 cracks or defects, especially about the interior orifice of the vent, of which impressions are to be 
 taken in wax at regular intervals in the manner prescribed on page 26, or in such other manner 
 as the Bureau may direct. If they show that the vent is corroded in furrows, and enlarged 
 considerably in diameter at its junction with the bore, a permanent impression is to be taken 
 in lead to show the conical enlargement. The following manner, practiced at the Experimental 
 Battery at Washington, is recommended: 
 
 IMPLEMENTS REQUIRED. 
 
 1. A soft wire about 0.07 in. diameter, and 3 or 4 fathoms long. 
 
 2. A lever about twice the length of the bore, and about 3 inches in diameter, and shod 
 to suit the curve of the bore nearly. 
 
 3. A small button of soft lead, judged to be of sufficient size to fill the vent at least one 
 inch from the bore. This is to be pierced lengthwise to receive the wire. 
 
 TO TAKE THE IMPRESSION. 
 
 Shove the wire through the vent; let it pass along the bore and out 'at the muzzle; put it 
 through the leaden button and tie a knot at the end. Draw the wire back through the vent 
 until the leaden button is introduced firmly into the inner orifice. 
 
 Apply the lever, making its shoe bear on the button, and force it well in by repeated 
 blows, the muzzle being the fulcrum. This done, disengage the button by pushing in the 
 priming-wire. 
 
 In taking impressions of the vent and cracks, each button in turn is used as a pattern for 
 moulding its succsssor, allowing for the progressive enlargement of the vent, or the cracks 
 emanating from it. When the crack shows itself, the head of the button should be so enlarged 
 as to include it. 
 
0. 
 
 I /**^W 
 
 O 
 
 to 
 O, 
 
 
 u 
 p 
 
 p 
 
 - 
 
 
 
 d 
 o 
 
 S 
 
 I 
 
 
 
 - 
 - 
 
 o 
 
 CM 
 
 m 
 
 ; 
 
 
 ^ 
 
 
 r> ! 
 
 r^ 
 
 o 
 
 PC 
 
 C 
 O 
 
 
 
 in 
 
 S 
 
 - 
 
C>s. 
 
 CD 
 OO 
 
 o 
 
 !25 
 
 
 3 
 
 O 
 
 2" 
 
 Xi 
 
 
 o 
 in 
 
 4* 
 
33 
 
 They examinations should take place after every twenty fires, at least, and more frequently 
 any unusual enlargement of the vent or extension of cracks shall be developed and 
 indicate its speedy destruction. 
 
 Before each examination the bore of tho gun is to be carefully washed and dried. 
 
 In recording the measurements of the bore in extreme proof and after service, distinguish 
 between "indentation," which is the depression at the " seat of the shot, " which is always 
 below, and the "wear of the bore," which is generally above, and increase of bore or "en- 
 largement" from any other cause. 
 
 When from the appearance of tho bore at the interior orifice of the vent, and especially 
 when a crack or cracks appear to be extending rapidly, the vent so enlarged may be filled 
 with melted tin, zinc, or Babbitt metal; a tight-fitting sponge head being pushed to the bottom 
 of the chamber to close the interior orifice, and the other vent be drilled through for the pur- 
 pose of continuing the firing. 
 
 The precise time at which this is to be done will vary, according to circumstances; such 
 as quality of metal, charge, and elevation. 
 
 The endurance of a gun with service charges may be surely predicted by observation of 
 the progressive wear of the interior orifice of the vent. 
 
 There are certain general forms in which this enlargement takes place. They may be 
 classed as triangular, lozenge, quadrilateral, star, circular, and elliptic. (See plate.) 
 
 With the ordinary central vent, when subjected to a rapid, continuous fire, the enlarge- 
 ment usually takes the form of an isosceles triangle, the apex of one of the angles towards the 
 muzzle, and tlu3 other two perpendicular to it. 
 
 With the lateral vent of the Dahlgren system it usually takes the lozenge form, the cracks 
 extending from the opposite angles lengthwise of the bore. 
 
 With those rifled cannon in which the vent is bouched, the cracks appear around the 
 bouching, and although the bouching preserves the vent, yet the formation of fissures around 
 the enlarged orifice when once commenced causes a greater tendency to rupture. With the 
 vent not bouched, the wear in rifled cannon is about double that of the smooth bore. 
 
 So long as the wear of the vent is regular and without cracks, a mere enlargement is not 
 indicative of danger ; but when it reaches a diameter of four-tenths (.4) of an inch the vent 
 should be closed and a new one opened. 
 
 A gun of large calibre should not in service be expected to endure more than 400 or 500 
 rounds before it will be necessary to open the new vent, which, however, will be of no advan- 
 tage, unless the old one be closed at its interior orifice, on which the gases would otherwise 
 continue to act as a wedge. 
 
 The first distinct appearance of the cracks, as shown by the button, is the proper limit. 
 
 After the gun bursts, make a sketch or draft showing lines of fracture, and reserve 
 specimens to be sent to the Ordnance yard at Washington for trial of density and tensile 
 strength ; and if practicable, a photograph should be taken. 
 5 
 
34 
 
 PREPARATION OP GUNS FOR SERVICE. 
 
 After the guns have been received at the navy yards it is necessary to adjust the sights, 
 and, in the guns of the Dahlgren pattern, cut the screw hole in the cascable. 
 
 CUTTINJ} THE SCREW HOLE. 
 
 The boring and screw-cutting machine is a convenient portable hand drill-press, the use 
 of which is readily understood by any machinist. 
 
 The gun being carefully levelled and the trunnions placed horizontal, the position of the 
 centre of the screw hole, which in the guns of the Dahlgren pattern is tangent to the radius 
 of the breech, is marked on the neck of the cascable with a centre punch. 
 
 The machine is placed on the cascable, the boring shaft inserted in the hollow leading bar, 
 and its movable centre placed on the mark. The instrument is then set vertical, by a spirit 
 level on the cogged driving wheel and the four pairs of set screws on the clamp-head embra- 
 cing the cascable. 
 
 The centre is then removed and a drill inserted in the lower extremity of the boring shaft, 
 which, being held firmly by a shoulder and turned by a four-armed wrench, while pressed up 
 to the metal by slowly turning the cogged driving wheel, cuts the hole. This is successively 
 enlarged, by two or more counterbits, to the size of the body of the screw. 
 
 The cutter is then inserted in the leading bar, and the thread cut. 
 
 ADJUSTMENT OF THE SIGHTS. 
 
 The bore having been thoroughly cleaned, the axis is levelled by a spirit level; this may 
 be very conveniently done by the aid of the levelling bar. The axis of the trunnions is to be 
 placed horizontal, either by placing a small level on the trunnions, or, as more exact, by using 
 the trunnion square. If the trunnion square is used it will be proper to verify the position of 
 the line of sight, which is frequently incorrectly placed at the foundries. 
 
 The breech sight is then to be adjusted. 
 
 A brass head or tompion, fitted with a vertical arm, on which there is a ledge for a spirit 
 level, is then introduced into the bore, and the arm placed vertical by the spirit level and a 
 tangent screw. 
 
 The arm is pierced on its centre line with two holes one at the height of the prescribed 
 diameter of the muzzle, the other nt a height equal to the proper distance of the bottom of the 
 sight notch from the axis of the bore. A waxed thread or fine wire being stretched from the 
 upper hole to the centre of the sight notch will coincide with the line of sight traced on the 
 swell of the muzzle, the top of the reinforce sight mass, and the base line, if they are correctly 
 placed. It will also be parallel to the axis of the bore if the adjustment of the breech sight 
 is exact, and the top of the reinforce sight is made to coincide with it. 
 
 This is, however, seldom the case, and after the adjustment of the reinforce sight it is 
 necessary to verify it. 
 
 This is done by the levelling bar a square steel bar with parallel faces, somewhat longer 
 
3 
 
 o 
 
 20 
 
 07 
 
 J 
 
 I 
 
 
 m 
 o 
 
 01 
 co 
 
 m 
 co 
 
 O 
 
 3 
 O 
 
 o 
 
 o 
 o 
 
 
 . 
 
 
 
 
 ~> 
 

35 
 
 than the distance between the sights, the rear end of which is bevelled at CO , (the angle at 
 which the sight is placed*) 
 
 The outfcr end of this bar is placed on the reinforce sight, which has been previously 
 adjusted to the proper height, and the bevelled end in contact with the outer face of the sight 
 bar. The bar is then levelled by two screws placed near the inner end, and a spirit level on 
 
 its npper surface. 
 
 If then the bottom of the sight notch coincides with the bottom of the bar, the line of 
 
 eight is parallel to the axis; otherwise, the reinforce sight or the sight bar must be lowered 
 until coincidence is obtained. 
 
 A centre line on the bar verifies the coincidence of the line of sight, and also the motion 
 of the sight bar in the vertical plane. The bevel verifies the angle of the bar, and the dis- 
 tance between the outer faces of the sight notch and of the reinforce sight being also marked 
 on the levelling bar, verifies this adjustment. 
 
 Another method is sometimes and more advantageously used in adjusting the sights of 
 puns which have not been turned. 
 
 Twoyfron or wooden discs are turned to the exact diameter of the bore, 
 
 nxi twanr three feet longer than the boreX One of the discs ik placed near *ne hflttom ui yuo ^ t 
 borevfeie other just w/ithni the muzzle. /On \be part proiecting\eyond tire muzzlev there/is a j^ ,_> 
 double ffHuare, each/arm of^hich is divided inbo equal>parts and nayversed by a fine* 
 
 The ffauaro being set vertical by a spirit level or/plumb line, aruLii waxed thread/oN: wire 
 stretched auit/from the outerVarm through the/Wit, cutting equalVivisions on/eacbVind 
 passing through the centre of/tneNelit, it is evident tba\a line ofynght isN^btaine^r through/The 
 centre of nfetal\nd parallol/U) the aicis of the/bore. 
 
 Thijr method najs the/advantage of adjusting the sights/In any plane parallel to the axis, 
 as in the case of the aide sights of rifled and other cannon. ,-* 
 
 
 
 ADJUSTMENT OF THE SIDE SIGHTS. 
 
 The gun having been levelled, and the trunnions placed horizontal, a centre line is to be 
 drawn on the top of the left (or right) rimbase. 
 
 The support for the sight is then to be fitted to the breech, at the distance from this line 
 marked on the pattern sight for its calibre, with the bottom of the sight notch in the bar, 
 exactly the height of the front sight (one inch) above the upper surface of the rimbase ; the 
 sight bar perpendicular. 
 
 It is advisable to place a very thin sheet of rubber under the support to prevent the heads 
 of the screws from being jumped off by the vibration. The screws have the same thread as 
 those for the present reinforce sight. 
 
 After the breech sight is adjusted a parallel to the axis of the bore is to be drawn in the 
 usual manner, and the front sight screwed in on the rimbase. 
 
 Some trifling adjustment may then be required to bring the height of the top of the 
 front sight and the bottom of the sight notch parallel to the axis of the bore in both the 
 horizontal and vertical planes. 
 
37 
 
 REPORT. FORM (1.) 
 
 NOTE. The Proof Gun is to be entered at bead of each page In red ink. 
 
 CIIAKOE OF FURNACE, IN POUNDS. 
 
 NO. 
 
 NO. 
 
38 
 
 CHARGE OP FURNACE, IN POUNDS. 
 
 NO. 
 
 TOTAL IN POUNDS. 
 
 NO. 
 
MO. 
 
 COMBINATION OP METAL, PER CENTUM. 
 
 FOTNACK 
 
 FUEL. 
 
 BLAST. 
 
 NO. 
 
40 
 
 NO. 
 
 DATE OP CASTING. 
 
 TIME. 
 
 REQUIRED TO OBTAIN 
 COMPLETE FUSION. 
 
 KEPT IN FUSION. 
 
 OF FILLING MOULD. 
 
 REMAINED IN OPEN 
 PIT. 
 
 NO. 
 
41 
 
 rh uwiif to Iw nut, showing tlw ciMCt plicw nwtrt 
 
 
 MKAN DENSITY AND TENSILE STRENGTH OF 3 SPECIMENS. 
 
 MO. 
 
 NO. 
 
 AT FODKDBT. 
 
 AT WAIUIKOTON. 
 
 DKJI0TT. 
 
 TIXtlLZ mUWOTH. 
 
 DIUMTT. 
 
 
 
 
 ft 
 
 Con. 
 
 BMd. 
 
 Core. 
 
 HMd. 
 
 Con. 
 
 HMd. 
 
 Con. 
 
 
 
 
 
 
 
 
 
 
 
 
 % 
 
 
42 
 
 
 EXCESS OF ROUGH OVER FINISHED 
 
 GUN HEADS. 
 
 
 
 
 
 DIMENSIONS. 
 
 
 
 
 
 NO. 
 
 -- at Muz- 
 'ace. 
 
 "3 
 
 s 
 
 "2 
 00 
 
 Si 
 
 "S 
 t 
 v f: 
 
 3 
 
 ea . 
 
 00 
 
 8 at Breech 
 y Under. 
 
 LENGTH. 
 
 DIAMETER. 
 
 TIME OF BORING. 
 
 TIME OF TURN- 
 ING. 
 
 NO. 
 
 
 I 1 
 
 M 
 
 |J 
 
 W 
 
 CJ 
 
 S a 
 w 
 
 a 
 
 w 
 
 
 
 So 
 1- 
 
 w g 
 
 j 
 
 
 
 
 
 
 Inches. 
 
 Inches. 
 
 luchee. 
 
 
 
 
 
 "*1 
 
 
 
 
 
 
 
 
 
 
43 
 
 METAL WORKED. 
 
 NO. 
 
 AT FOURDKT. 
 
 AT WASHMOTOK. 
 
 CAVITIES, Ac. 
 
 NO. 
 
44 
 
 APPEARANCE AT FOUNDRY OP- 
 
 NO. 
 
 NO. 
 
 FRACTURE OF CORE. 
 
 CORE. 
 
 BORE. EXTERIOR SURFACE. 
 
NO. 
 
 WEIGHT OP 
 GUN. 
 
 PREPONDER- 
 ANCE. 
 
 DISTANCE FROM 
 BASE-RING TO CEN- 
 TRE OF TRUNNIONS. 
 
 MAXIMUM INDEN- 
 TATION BY POW- 
 DER PROOF. 
 
 DIAMETER OF BORE BY 
 8TAROAUUE, AFTER PROOF. 
 
 HO. 
 
 POD NIX. 
 
 POUNDS. 
 
 INGRES. 
 
 IOOOTHS or AN INCH. GREAT* r. 
 
 LlAlT. 
 
 
 
 
 Rfcbt. 
 
 Left. 
 
 
 
 
 
 
 
 
 * 
 
 
 
 
 
 
 
46 
 
 NO. 
 
 NAME OF INSPECTOR. 
 
 ARE THE INSPECTOR'S MEASURE- 
 MENTS WITHIN REGULATION 
 LIMITS J 
 
 NO. 
 
47 
 
 HO. 
 
 REGISTER. 
 NO. 
 
 REMARKS. 
 
 NO. 
 
48 
 
 REPORT. (FORMS.) 
 Dimensions of guns cast at the Foundry of , 18 
 
 CLASS. 
 
 LENGTHS FROM A, THE BASE, TO . 
 
 inch. 
 Ibs. 
 
 B. 
 
 C. 
 
 D. 
 
 e. 
 
 E. 
 
 F. 
 
 G. 
 
 H. 
 
 I. 
 
 K. 
 
 L. 
 
 Left. 
 
 Right. 
 
 Prescribed dimensions - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Foundry No. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DIAMETER AT . 
 
 
 A. 
 
 C. 
 
 D. 
 
 E. 
 
 F. 
 
 G. 
 
 H. 
 
 I. 
 
 K. 
 
 L. 
 
 Gun. 
 
 Rimbases. 
 
 Prescribed dimensions. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Foundry No. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 * 
 
 
 MISCELLANEOUS. 
 
 
 LENGTHS. 
 
 Diameter of 
 bore. 
 
 ! 
 
 WEIGHT OF GUN. 
 
 Preponder- 
 ance at base. 
 
 
 
 fe4 
 fl 
 
 o 
 
 Int. of vent, 
 dist'ce from 
 a. 
 
 Int. of vent 
 dist'ce from 
 axis. 
 
 Bore, 
 a c. 
 
 Chamber, 
 ab. 
 
 Lbs. 
 
 Prescribed dimensions - 
 
 
 
 
 
 
 
 
 
 
 
 
 Foundry No. 
 
 
 
 
 
 
 
 
 
 
 
 
\ 
 
 "y > 
 
49 
 
 R E I'O R T .(FORM 2) Continued. 
 
 X. 
 
 X. 
 
 O. 
 
 (REK DIAGRAM.) 
 
 P 
 
 LKHOTH or TRi-.i- 
 
 noM. 
 
 
 KKMAKKN. 
 
 
 Left. 
 
 Rlbt 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 - 
 
 
 C'.vIlndiT gnge dMcciub. 
 
 (SEE DIAGRAM.) 
 
 U. 
 
 N. 
 
 O. 
 
 p. 
 
 TKUXMOXS. 
 
 RIMBA8U. 
 
 Tmnnlonn 
 below *xi> 
 
 
 Left. 
 
 lilt-Ill. 
 
 Left. 
 
 Right 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 CHAROEI or Povt- 
 Dot. tu. 
 
 Powder, bjr whom 
 Kurt-. mxld.tr of 
 mUBftctan. 
 
 IMTUI. TELOriTT 
 
 or rowoiK, FKKT. 
 
 WEIGHT or PIMM- 
 TILE. LBS. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
50 
 
 REPORT. (FORM 3.) 
 
 The excess over prescribed diameter of bore before and after proof, as found by the star gauge, at different 
 der ( inches from face) to seat of shot; thence at every * inch** to trunnions, ( 
 
 searched for and recorded, with its distance from face ; thus 
 
 Calibre and No. of Gun. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 inch > B. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Foundry No. ) A. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 inch } B. P. 
 Foundry No. ) A. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 inch ) B. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Foundry No. S A. P. 
 
 
 
 
 
 
 
 
 & 
 
 
 
 
 
 
 
 
 inch IB. P. 
 Fonnflry No. ) A. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 inch IB. P. 
 Foundry No. J A. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 inch }B. P. 
 Foundry No. J A. P. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
51 
 
 REPORT. (FORM 3 Continued. 
 
 distance* from the muzzle, to lie taken at every J inch from the bottom of the cylin- 
 
 inches from the face ;) thence every five inches. The greatest enlargement to be 1 
 
 ii 
 
 ih 
 
 !i 
 
 
 
 
 
 
 
 iz S i fc 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .! 
 
 m i s 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 -