i 
 
lime n* 
 
 LIBRARY 
 
 UNIVERSITY OF 
 CAltfOtNIA 
 

 
A TREATISE 
 
 LIGHTNING CONDUCTORS; 
 
 COMPILED FROM 
 
 A WORK ON THUNDERSTORMS, BY 
 S. W. HARRIS, F.R.S., 
 
 AND OTHER 
 
 STANDARD AUTHORS. 
 
 LUCIUS LYON, A.M. 
 
 NEW-YORK: 
 GEORGE P. PUTNAM, 10 PARK PLACE. 
 
 M.DCCC.LIII. 
 
 
ENTERED, according to Act of Congress, in the year 1853, by 
 
 Lucius LYON, A. M., 
 
 in the Clerk s Office of the District Court for the Southern District of 
 New-York. 
 
PREFACE. 
 
 IT is not a little remarkable, when we consider the 
 prevailing disposition of the times to apply the dis 
 coveries of natural science to useful purposes, and to 
 embody them in those material forms which make 
 them subservient to the wants of man, that, among 
 the books which are incessantly issuing from the 
 press, none has yet appeared, in this country, ex 
 clusively devoted to the subject of practical elec 
 tricity. Theoretically, indeed, the study of the phe 
 nomena of electricity awakens a lively interest in 
 every mind, both on account of the wonderful de 
 velopments which are constantly made, and the 
 subtle and mysterious nature of its essence ; seeming, 
 as it does, to occupy the interval between mind and 
 matter; but, since the brilliant experiment of Dr. 
 
PREFACE. 
 
 Franklin, identifying lightning with electricity, al 
 though much information has been acquired, both in 
 this country and abroad, no treatise has been pub 
 lished, exhibiting to the American reader those facts 
 which are necessary for his guidance, in applying 
 the discovery of Franklin successfully to the protec 
 tion of life and property. 
 
 The only explanation of this circumstance which 
 can be given is, that the construction and applica 
 tion of lightning conductors, has appeared to most 
 persons a matter too simple to need any aid from 
 books, while not a few have looked upon the whole 
 theory as absurd, and as a source of danger rather 
 than of safety. There has been, consequently, but 
 little encouragement for the compiling of a work 
 calculated to bring before the community all that 
 has been learned on this subject. 
 
 The various systems of rodding, however, which 
 have sprung up of late, and the different modifica 
 tions of the conductor, which have been patented 
 and presented to the public, each claiming some 
 peculiar advantage over all its competitors, have 
 created a curiosity, if not a necessity, which seems to 
 justify the publication of the present volume. 
 
 The valuable treatise recently published in Lon 
 don, from the pen of S. W. Harris, F. E. S., is quite 
 
PREFACE. V 
 
 too expensive to admit of general circulation ; and 
 it is thought, too, that one less extended will be 
 better adapted to the wants of the American public. 
 The compiler of the following work has, therefore, 
 aimed to comprehend within reasonable limits all 
 the facts that are essential, omitting such details as 
 are merely curious, or such as suggest no new and 
 valuable application of science. He has made a free 
 use of all the materials within his reach, referring, 
 for the satisfaction of the reader, as well as in justice 
 to his authorities, to the book and page from which 
 they have been derived. 
 
 There can be no doubt of the utility of such a 
 book as is here presented. After expending large 
 sums of money for the most approved apparatus of 
 rods, many persons have been bitterly disappointed 
 in their expectations, and have received no adequate 
 return for their outlays. The truth is, that our 
 countrymen have not acted on this subject with that 
 shrewdness for which, in other things, they are pro 
 verbial. They have taken too much upon trust, and 
 neglected the investigation of the facts. The iron 
 conductors, put up at no inconsiderable cost, and 
 supposed to secure perfect safety to the structures 
 which they surmount, instead of proving themselves 
 faithful sentinels and guardians in the hour of peril, 
 
VI PREFACE. 
 
 have too often turned traitors, and invited the de 
 struction which they promised to avert. The "swift 
 fire of Jove, hurled by his red right arm," has not 
 unfrequently bolted from the iron track, prepared 
 for its harmless descent, and, indignant at some de 
 fective joint, or sudden break, or the want of suf 
 ficient metal for its free discharge, has made a 
 forcible passage for itself, often leaving shattered 
 walls, and chimneys, and blazing roofs, to attest its 
 terrific power. Happy for the sufferers if the blasted 
 corpse of some loved one has not added unutterable 
 woe to the desolation of the scene ! 
 
 Such disastrous consequences are due, in part, 
 to imposture, but far more frequently to the igno 
 rance and carelessness of workmen, and to the blind 
 credulity of those who have employed them. In 
 many instances, too, the owners of property have 
 suffered an apparatus, originally well adjusted, to 
 get out of repair. The distrust which might have 
 arisen from these accidents, has no doubt been miti 
 gated or prevented, in a great degree, by the diffi 
 culty of detecting any defect in a system of con 
 ductors a philosophical knowledge of the sci 
 ence of electricity often being requisite for doing 
 so. 
 
 Partly from the imperfections alluded to above, 
 but much more from the unaccountable apathy which 
 
PREFACE. 
 
 exists on the whole subject, a very large proportion 
 of the owners of buildings in this country, and proba 
 bly a still greater proportion in other countries, have 
 neglected to avail themselves of the lightning con 
 ductor in any form. An incalculable amount of 
 property, and many lives, which might be made at 
 least relatively secure, are thus constantly and need 
 lessly jeopardized. How great a risk is incurred, 
 and how nearly absolute safety is attainable by con 
 ductors, the author hopes to demonstrate in the fol 
 lowing pages. 
 
 Mr. Harris, in his unrivalled work on Thunder 
 storms, has the following appropriate Introduc 
 tion: 
 
 " The fact of electrical conduction by metallic substances 
 having been so long and so well established, any further dis 
 cussion of the application of this principle to the purpose of 
 protection against lightning may possibly appear to persons, 
 conversant with such subjects, as in some degree superfluous. 
 The damage, however, which so frequently occurs in thun 
 derstorms, attended as it is with loss of life, and with serious 
 inconvenience to the best interests of the country, may be 
 fairly adduced as a sufficient reply to such an opinion. 
 
 " The beautiful spire of St. Martin s church, in London, 
 has been recently rebuilt, at a cost of full one thousand 
 pounds sterling, in consequence of an explosion of lightning, 
 
Vlll PREFACE. 
 
 which fell on it in July last. Brixton church, near London, 
 had also to undergo extensive repairs, rendered necessary 
 from the same cause. In January, 1841, the spires of Spit- 
 alfields and Streatham churches, were struck by lightning, 
 and the latter nearly destroyed ; and in August of the same 
 year an electrical discharge shook the spires of St. Martin s 
 and St. Michael s churches, at Liverpool, both modern edi 
 fices of a costly and elaborate construction. In January, 
 1836, the spire of St. Michael s church, near Cork, was rent 
 by lightning down to its very base; and in the following 
 October the magnificent spire of Christ church, Doncaster, 
 was almost totally destroyed by a similar discharge. 
 
 " Thus, in the United Kingdom alone, and within the 
 short space of five years, we find at least eight churches to 
 have been either severely damaged or partially demolished 
 by lightning ; to this list of casualties may be added the 
 fine old church of Exton, in Rutland, which, according to the 
 public journals, was in great measure destroyed in a thunder 
 storm, so lately as the 25th of last April. A writer in 
 NICHOLSON S Journal of Science, states that he has made a 
 calculation of the average annual amount of damage done 
 by lightning in England alone, and that it cannot be tar short 
 of fifty thousand pounds. 
 
 " In the British Navy the effects of lightning have been 
 most disastrous. Since the commencement of the war in 
 1793, more than two hundred and fifty ships are known to 
 have suffered in thunderstorms. It is not possible to state 
 with any degree of precision the total amount of damage 
 
PREFACE. IX 
 
 done, as all the instances in which ships have suffered cannot 
 be well ascertained : some idea, however, may be formed of 
 it from the following facts, derived from the official journals 
 of Her Majesty s ships, deposited at the Admiralty. In one 
 hundred and fifty cases, the majority of which occurred be 
 tween the years 1799 and 1815, nearly one hundred lower 
 masts of line-of-battle ships and frigates, with a correspond 
 ing number of topmasts and smaller spars, together with va 
 rious stores, were wholly or partially destroyed. One ship 
 in eight was set on fire in some part of the rigging or sails ; 
 upwards of seventy seamen were killed, and one hundred and 
 thirty-three wounded, exclusive of nineteen cases in which 
 the number of wounded is returned as many or sever 
 al. In one-tenth of these cases the ships were completely 
 disabled, and they were compelled in many instances to 
 leave their stations, and that too at a critical period of our 
 history. The expenditure in these few cases in the mere 
 material, could not have been far short of one hundred thou 
 sand pounds sterling. So that if the whole amount of the 
 loss to the public, in men, in money, and in services of ships, 
 could be ascertained, it would necessarily prove to be enor 
 mous ; more especially when we take into account the ex 
 pense of the detention and refit of the damaged vessels, the 
 average cost of a single line-of-battle ship to the country 
 being one hundred pounds per diem and upwards. Now 
 between the years 1809 and 1815, that is to say, within the 
 short period of six years, full thirty sail of the line, and fif 
 teen frigates, were more or less disabled. 
 
X PREFACE. 
 
 " A very considerable portion of this mass of destruction 
 occurred, it is true, at a time when a great number of ships 
 were required ; but at a more recent period, in time of peace, 
 when the Navy has been greatly reduced, we find a large 
 amount of these casualties to be constantly occurring. On 
 the Mediterranean station alone, between the years 1838 and 
 1840, the Rodney, Powerful, Ceylon, Tribune, Scorpion, 
 Wasp, Tyne, and Blazer, were struck by lightning, and 
 many of them severely damaged : the Rodney, in addition 
 to the destruction of her mainmast, was set on fire. In little 
 more than twelve months, about the year 1830, three line- 
 of-battle ships, a frigate, and a brig, were also more or less 
 disabled. In other parts of the world we have lately had 
 the Rhadamanthus, Gorgon, Snake, Racehorse, Pique, and 
 many others, damaged by lightning; and in 1832, the South 
 ampton, of fifty guns, narrowly escaped being blown up in 
 the Downs. 
 
 " It has been suggested that many ships reported as 
 missing, have been destroyed in thunderstorms, a surmise 
 almost converted into a reality, by the ravages which light 
 ning is known to be capable of producing. From a refer 
 ence to the official log of the Lacedcemonian, and to the evi 
 dence of Admiral Jackson, who then commanded her, it ap 
 pears, that His Majesty s ship Peacock disappeared during a 
 violent storm of lightning on the coast of Georgia, in the 
 year 1814. The Loup Cervier, another of His Majesty s 
 ships, was last seen off Charlestown, on the evening of a se 
 vere thunderstorm, and has not since been heard of. When 
 
PREFACE. 
 
 His Majesty s ship Resistance, of forty-four guns, was blown 
 up by lightning in the Straits of Malacca, in the year 1798, 
 two or three of the crew were picked up by a Malay proa, 
 which happened to be in company ; but for this circum 
 stance, the fate of this ship would have remained in the same 
 obscurity which now hangs over so many vessels reported 
 as * missing, as all the rest of the crew perished. 
 
 " The journals of the ships of the Honorable East India 
 Company furnish appalling statements of the damage and 
 loss of life, caused by the electrical explosions which have 
 fallen on them, while freighted with the rich products of the 
 East : even so lately as 1842, the Coote, of twenty guns, one 
 of the navy of this great mercantile power, had her masts 
 shivered in pieces by lightning at Madras. 
 
 " Though we have not the same means of ascertaining 
 the damage done to our mercantile marine, yet the loss to 
 the shipping interest, in consequence of lightning, must be 
 extremely great. Scarcely a year passes, without a calami 
 tous account appearing in the public prints, of some fine 
 merchant ship having been damaged or totally destroyed. 
 In March last, the Toronto, one of the splendid packets which 
 sail between London and New-York, was struck by light 
 ning, which killed one of the crew, *nd damaged the vessel ; 
 and in August, 1842, the Defiance, a large transport laden 
 with Government stores, including rockets and gunpowder, 
 had her mainmast completely rent through to the keel by 
 an electrical discharge off Nankin ; the ship was filled with 
 a sulphurous smoke, and the greatest consternation prevailed 
 
Xll PREFACE. 
 
 among the troops and seamen, from the dread of an imme 
 diate explosion. In May, 1840, the ship Madras was set on 
 fire, and a portion of her side was driven out by an electrical 
 explosion, and in 1839 a similar accident befel a large barque 
 called the John and James off Algiers, so that she was with 
 difficulty prevented from sinking. In 1838, the Orwell, a 
 large trader laden with cotton, was set on fire, and narrowly 
 escaped total destruction. Within a few years the merchant 
 ships Tanjore, Poland, Logan, Ruthelia, Bolivar, Boston, 
 and Lydia, are known to have been entirely consumed. 
 
 " However well, therefore, the fact of electrical conduc 
 tion may be known, however well scientific men may bo 
 agreed that, by the judicious employment of metallic bodies, 
 we may ensure protection against lightning, certain it is 
 tliat the principle itself is far from being generally under 
 stood, or universally adopted. Indeed, to existing prejudices 
 arising entirely out of a misapprehension of the laws of elec 
 trical discharge, may be traced the great destruction of life 
 and property so frequently occurring from the effects of 
 lightning. 
 
 " It is not easy to explain how, in the present advanced 
 state of natural knowledge, so many anomalous views and 
 opinions on this interesting subject should pervade the public 
 mind, since in no department of physical science is the field 
 of observation more fertile, or the path of experience more 
 direct and certain. We have at our command the results 
 of observation for nearly a century, during which time light 
 ning rods have been employed ; a great many instances are 
 
PREFACE. Xlll 
 
 to be found, in which lightning has fallen on buildings un 
 der a variety of peculiar circumstances. In some cases light 
 ning rods have been present, in others not: moreover, we 
 can successfully imitate by artificial means the great opera 
 tions of nature, and examine experimentally every probable 
 result of a shock of lightning, and every possible contingency 
 attendant on it. We ought, therefore, to find no difficulty in 
 arriving at a practical solution of such questions as these : 
 Is the application of a lightning conductor desirable in any 
 particular case ? May it, by a species of attractive force in 
 herent in it, cause a discharge of lightning, which, otherwise, 
 would not have occurred in this particular direction ? If so, 
 may it occasion the damage it was set up to avert, through 
 its inability to meet the explosion that may fall on it ? Is it 
 liable to produce destructive effects, by any species of lateral 
 discharge of the electricity in passing along it ? What are 
 the best dimensions and form of a lightning conductor ? and 
 such like. If such questions as these cannot now be deter 
 mined, they in all probability never will be." 
 
 Now if this unpretending volume, by attracting 
 a more careful attention to practical electricity, and 
 by diffusing in this community all the important in 
 formation that has yet been elicited on this subject, 
 shall be the means, under God, of preserving the 
 property of any individual, or of preventing the loss 
 of a single life, the author will feel that the time and 
 
XIV PREFACE. 
 
 labor devoted to its preparation will be amply com 
 pensated by the amount, however small, thus contri 
 buted to the sum of human happiness. 
 
 Lucius LYON. 
 
CONTENTS. 
 
 SECTION I. 
 
 GENERAL VIEW OF NATURAL AND ARTIFICIAL ELECTRICITY. 
 
 Electricity considered in relation to common matter, 3. Electrical 
 conditions of a thunderstorm, 12. Insulation Conduction 
 Charge Discharge, &c., 17. Identity of common electricity 
 with the agency of lightning, 23. Nature of ordinary electrical 
 arrangements producing artificial lightning, 27. Various phe 
 nomena of lightning and thunder, 34. Appearances termed 
 fire-balls, 38. Sulphurous odor of the electric discharge, 42. 
 Artificial disruptive discharges, 44. Further observations on 
 thunder-clouds, 49. Electrical discharges, 52. Ascending or 
 upward stroke, 59. 
 
 SECTION II. 
 
 APPLICATION OF METALLIC CONDUCTORS TO THE DEFENCE 
 OF BUILDINGS AND SHIPPING FROM LIGHTNING. 
 
 Laws and operation of disruptive discharge, 69. Observed effects on 
 buildings and ships, 74. St. Martin s church struck by light- 
 
XVI CONTENTS. 
 
 ning, 76. Brixton church struck by lightning, 83. Nature of 
 lightning rods, 89. Laws of electrical conduction, 92. Mechani 
 cal effects of the electrical discharge, 94. What quantity of 
 metal is requisite for a lightning rod? 105. How far does the 
 protecting power of a lightning rod extend ? 110. 
 
 SECTION III. 
 
 RESULTS OF THE APPLICATION OP LIGHTNING RODS TO 
 BUILDINGS AND SHIPS. 
 
 FROM THE PERIOD OF THEIR FIRST BEING EMPLOYED IN 
 THE YEAR 1760. 
 
 Introductory remarks, 117. Whe lightning rods and other me 
 tallic conductors have effectually guarded buildings, <fec. against 
 damage by lightning? 118. Whether lightning rods attract 
 lightning? 132. Whether in certain cases pointed condnctors 
 actually prevent explosions of lightning from falling on build 
 ings ? 141. Phenomena observed, when a dense explosion of 
 electricity falls on a lightning rod, 152. Harmless character of 
 the luminous appearances observed on lightning rods, 154. 
 Division of the charge, 156. Instances in which buildings pro 
 vided with pointed conductors are said to have been damaged 
 by lightning, 158. Precautions when exposed to the action of 
 thunderstorms, 170. Construction of lightning rods applied 
 to buildings, 171. Practical deductions, 184. Concluding ob 
 servations, 187. 
 
SECTION I. 
 
 GENERAL VIEW OF NATURAL AND 
 ARTIFICIAL ELECTRICITY. 
 
 Electricity considered in relat in to common matter Conditions of 
 a Thunderstorm Insulation Charge Conduction Discharge, 
 <fe c> Identity of Natural and Artificial Electricity Nature of 
 ordinary Electrical arrangements producing Disruptive Dis 
 charge Various Phenomena of Thunder and Lightning Ap 
 pearances termed Fire Ba]ls Sulphurous odor of the Electrical 
 Discharge Artificial discharges of various kinds Luminous 
 appearances similar to those in Nature Further observations 
 on Thunder Clouds Electrical Discharges Possible Causes of 
 Discharge Upward Discharge. 
 
NATURAL 
 
 AND 
 
 ARTIFICIAL ELECTRICITY. 
 
 Electricity considered in relation to Common Matter. 
 
 BEFORE entering upon the subject of the application 
 of metallic substances to buildings and ships, with a 
 view to their protection from lightning, it may not 
 be unimportant to review the amount of information 
 we are in possession of, relative to the nature and 
 operation of thunderstorms. 
 
 A large induction of facts, leaves little doubt of 
 the existence of some elementary or primordial prin 
 ciple in nature, every where present, and intimately 
 associated with the particles of common matter, ac 
 cording to some general law. In what this element 
 consists, we are quite ignorant ; we know, however, 
 that there is such a constituent principle, and that it 
 is capable of exerting, under given circumstances, an 
 all-powerful action ; hence it may be considered as a 
 
4 ELECTRICITY CONSIDERED 
 
 species of unknown physical force or agency, the 
 laws of which it is our business to investigate. 
 
 Now it is no objection to the practical results of 
 such an inquiry, to say that we are ignorant of the 
 nature of the agency with which we are dealing it 
 being the great end of modern philosophy rather to 
 trace, and apply the uniform relations of certain 
 facts, than to speculate upon the nature of the mys 
 terious causation, upon which the connection de 
 pends. Thus Newton was content to examine the 
 laws of gravity, and the relations of this force to 
 common matter, without in any way meddling with 
 its nature as an occult cause ; and from this method 
 of inquiry the happiest consequences have resulted. 
 The same method is equally applicable to the subtle 
 principle active in a thunderstorm : we may arrive 
 at all the practical information we require relative to 
 this grand yet fearful display of its powers, even 
 although we should never understand its nature as a 
 primary source of causation. 
 
 This physical force or agency has been termed 
 electricity,* and there is some strong evidence for 
 supposing it to be an extremely attenuated and 
 subtle kind of matter differing, however, in its 
 properties from any form of matter of which we 
 have cognizance. 
 
 It is insensible to ordinary perception so long as 
 it is distributed amongst the particles of bodies ac- 
 
 * The Greeks observed its effects in amber, faftcrpov, hence the 
 term. 
 
IN RELATION TO COMMON MATTER. 5 
 
 cording to a given law. In this state it is said to be 
 neutral, or inactive ; when, however, the equilibri 
 um of distribution is from any cause disturbed, then 
 a variety of interesting phenomena begin to appear, 
 and the electrical agency manifests a tendency to re 
 turn to its previous state of quiescence. 
 
 A variety of natural and artificial ^operations 
 affect the neutral electrical state of matter. Under 
 natural operations, may be classed changes of tem 
 perature, changes in the form of bodies, chemical 
 changes, &c. ; thus brimstone, chocolate fresh from 
 the mill, wax, resin, &c., when melted, become elec 
 trical in cooling; the tourmalin, also, and many 
 other substances, evince electrical signs under a 
 change of temperature. In the decomposition of 
 water, by means of sulphuric acid and zinc, we find 
 the bottle in which the chemical action is proceeding 
 strongly electrical ; and it is a remarkable fact, that 
 during the progress of thunderstorms, the vapor of 
 the atmosphere is condensed into rain, or frozen into 
 hail, and the general temperature of the air altogether 
 changed. 
 
 Hence, from the sum of our knowledge respect 
 ing meteorological phenomena, there appears great 
 reason to conclude, that the causes which produce 
 artificial electricity are all in full operation in the 
 masses of vapor, among which natural electricity 
 appears active. 
 
 This opinion is maintained by several eminent 
 electricians of the present day. It was warmly es 
 poused by the late Mr. Singer, who advanced in 
 
6 ELECTRICITY CONSIDERED 
 
 support of it the following positions : (1.) That the 
 electrical phenomena of the atmosphere take place, 
 in all climates, to the greatest extent, about the 
 period of the greatest degree of heat, when the rays 
 of the sun have caused a considerable accumulation 
 of vapor. (2.) Where this cause operates to the 
 greatest extent, as, for instance, within the tropics, 
 natural electricity is produced on the largest scale. 
 (3.) When the natural source of evaporation is 
 assisted by collateral causes, electrical changes occur 
 with astonishing activity, as in the eruption of a 
 volcano, or the heat imparted to the air in its pas 
 sage over large extents of hot sands, as those of 
 Africa. (4.) By the action of winds, currents of air 
 of different temperatures are often mixed, so that 
 such as have been heated and charged with moisture, 
 become suddenly cooled, thus occasioning a precipi 
 tation of water, and the occurrence of electrical 
 changes. This is often witnessed on the coast of 
 Guinea during the existence of the Harmattan. 
 (5.) These electrical changes are every where most 
 frequent when the causes of evaporation and conden 
 sation suddenly succeed each other. 
 
 After advancing several cogent arguments in 
 favor of the above facts, and noticing, in a very can 
 did manner, some objections urged against the theo 
 ry they are intended to support, Mr. Singer con 
 cludes with the following truly appropriate and 
 judicious observations: "Although the immediate 
 causes by which the various phenomena of the at 
 mosphere are produced, be still far beyond our com- 
 
IN RELATION TO COMMON MATTER. 7 
 
 prehension, yet the connection of their several effects 
 is a sufficient demonstration that they are not purely 
 mechanical, but subservient to the direction of su 
 preme power and intelligence. By this means, the 
 most simple arrangement becomes the source of sub 
 lime effects. The process of evaporation which 
 modifies the action of the sun s rays, and conveys to 
 every part of the earth s surface a source of fertility, 
 does at the same time diversify the appearance of 
 the atmosphere by an endless variety of imagery, 
 enlivening the horizon with the most brilliant and 
 glowing tints, and in all probability effecting those 
 electrical changes which are the precursors of the 
 most magnificent phenomena in nature." 
 
 Under artificial operations may be classed fric 
 tion, pressure, and other mechanical actions: the 
 electrical machine, essentially a plate or cylinder of 
 glass, made to revolve between or against fixed 
 cushions, is sufficiently illustrative of this we ob 
 serve brilliantly luminous sparks fly round the 
 glass, and dart off from a metallic substance opposed 
 to it, in consequence of the disturbed state of the 
 electrical distribution in these bodies. 
 
 Amongst the various relations of electricity to 
 common matter, we find the following : Some 
 bodies facilitate the transmission of electrical action 
 in so much greater degree than others, that they 
 have been considered in the light of conductors of 
 electricity ; other bodies, on the contrary, admit of 
 so little freedom in this respect that they have been 
 denominated non-conductors, or insulators of electri- 
 l* 
 
8 ELECTRICITY CONSIDERED. 
 
 city. The distinction, however, between conductors 
 and non-conductors, although more or less arbitrary, 
 may still be sufficiently defined for practical pur 
 poses : thus all the metals more particularly may 
 be taken as conducting bodies, whilst all vitreous 
 and resinous substances may be considered as non 
 conducting bodies, or insulators. Hence it is, that 
 we find the metallic conductors opposed to the cyl 
 inder of an electrical machine, supported on a glass 
 pillar ; by which the active electricity developed by 
 the friction, becomes as it were imprisoned, and 
 accumulated on the metal. 
 
 It should, however, be clearly understood, that 
 there are no substances which perfectly conduct or 
 perfectly obstruct the transmission of electricity, their 
 insulating or conducting power being only a differ 
 ence in degree : still the differences are so great be 
 tween various substances, that if classed in relation 
 to such differences, those at the extremes of the 
 series admit of being considered, the one as conduc 
 tors, the other as insulators. Thus, while vitreous 
 and resinous bodies admit of but extremely slow 
 conduction, during which sensible and even consid 
 erable portions of time elapse, metallic bodies allow 
 conduction to proceed with incredible rapidity. Pro 
 fessor Wheatstone, by a highly ingenious experimen 
 tal process, has clearly shown, that the transmission 
 of accumulated electricity through a copper wire, 
 one-fifteenth of an inch in diameter, and about half 
 a mile in length, proceeds at the rate of 576,000 
 miles in a second of time ; supposing the electrical 
 
IN RELATION TO COMMON MATTER. 
 
 action to move from one extremity to the other; and 
 that the light of the spark produced by it, has a less 
 duration than the one-millionth part of a second. 
 
 The learned Mr. Cavendish, in the course of 
 some extensive inquiries into the electricity of the 
 torpedo, found the difference between the conducting 
 powers of iron and water, to be nearly in the ratio 
 of four hundred millions to one ; that is to say, elec 
 tricity meets with no more resistance in passing 
 through an iron rod four hundred millions of inches 
 long, than it would meet with in passing through a 
 column of water of the same diameter, only one inch 
 long.* 
 
 TABLE shoiuing the order of the Conducting and Insu 
 lating Powers of various Substances. 
 
 CONDUCTORS. 
 
 INSULATORS. 
 
 1 
 | 
 
 All known metals. 
 Well-burned charcoal. 
 Plumbago. 
 Burning gaseous matter, as flame. 
 
 4 
 1 
 
 Ice at of Fahrenheit. 
 Dried vegetable substance. 
 Dried animal substances. 
 Parchment. Leather. Feathers. 
 Baked wood. 
 
 i 
 
 Concentrated acids. 
 
 1 1 Oils and fatty substances. 
 ^ 1 Bituminous matter. 
 
 
 Dilute acids. 
 
 I Bilk. 
 
 V 
 
 Saline fluids 
 
 
 
 
 I 
 
 Living animals. 
 Living vegetables. 
 Wood in its ordinary state. 
 Snow and ice. 
 
 I 
 
 Animal fur and hair. 
 Dry gases, including the atmos 
 phere. 
 Pure steam of high elasticity. 
 Glass and all vitrefactions. 
 
 [" Aqueous vapor. 
 -g Common earth and stone. 
 
 1- 
 I 
 
 Diamond. Transparent gems. 
 Talc. 
 
 I Dry chalk and lime. 
 S, | Marble and porcelain. 
 s Paper. 
 
 
 
 Amber. 
 All resins and resinous bodies. 
 Brimstone. 
 
 [Alkaline matter. 
 
 
 Shell-lac. 
 
 * Phil. Trans, for 1834, Part II. 
 
10 ELECTRICITY CONSIDERED 
 
 If we arrange various kinds of substances in 
 series, according to the comparative degree of resist 
 ance they offer to the transmission of electricity, we 
 obtain the following order. The first column in the 
 preceding Table contains the best conductors, and 
 leads by degrees into the second column, in the 
 order of their increasing resistance, until we arrive 
 at the opposite extreme. 
 
 The order above given, is sufficiently near the 
 truth : it is almost impracticable, however, to assign 
 the exact place of some of the equivocal substances, 
 more especially as their conducting power is liable 
 to vary from many accidental causes. All charcoal 
 will not conduct equally well, and some bodies which 
 conduct badly as solids, will, by a change of temper 
 ature up to fluidity, become immediately conduc 
 tors : thus ice at . of Fahrenheit is an insulator, 
 but on approaching the melting point it becomes a 
 conductor; the conducting power of green vegeta 
 bles, and raw meat, depends on the fluids they con 
 tain. The extremes of the series, however, are per 
 fectly defined ; if we commence with the metals we 
 have the order of conducting power, and conversely, 
 by commencing with shell-lac, we have the order of 
 insulating power. 
 
 For the purpose of a greater degree of generali 
 zation, we may include, in the conducting class, all 
 metals and metallic ores, acids, saline bodies, all 
 fluids except oils, also stones and earthy matter, liv 
 ing animals and vegetables. 
 
 Under the insulating class, we may comprise all 
 
IN RELATION TO COMMON MATTER. 11 
 
 resinous and bituminous matter, all vitreous matter, 
 all gaseous matter, precious stones, dry animal and 
 vegetable matter, silk and oils. 
 
 The following is an easy and simple experimental 
 illustration of the conducting and insulating power 
 of various bodies in respect of ordinary electricity. 
 
 Let a succession of sparks about two inches in 
 length, continue to pass from the insulated conductor 
 of an electrical machine to a metallic ball in connec 
 tion with the ground. Apply now a stick of sealing- 
 wax, or a dry rod of glass, to the conductor, no 
 sensible effect will be produced on the current of 
 sparks. But if the conductor be touched with a rod 
 of wood, or put into communication with the walls 
 of the building, the sparks will immediately cease, 
 evidently showing that the accumulated electricity 
 had been by these last substances carried off, whilst 
 the wax and glass evinced no such power. In this 
 way we may test the conducting power of the vari 
 ous substances above given, either directly, or by in 
 closing them in non-conducting tubes. 
 
 Although the distinction between conductors and 
 non-conductors of electricity is to a great extent 
 arbitrary, yet it is plain from the above facts, that 
 such a distinction, in a positive sense, is quite ad 
 missible. Thus the substances commencing the first 
 column of the preceding table, may be taken as 
 being more especially conductors ; those terminating 
 the second, as obstructors or non-conductors of elec 
 tricity : and the great practical fact which marks the 
 distinction between them is this, that the substances 
 
12 ELECTRICAL CONDITIONS 
 
 considered more especially as insulators, oppose such 
 complete resistance to the transmission of electrical 
 action, that an instantaneous return of the disturb 
 ance to a state of quiescence (p. 4), is never effected 
 through them, without mechanical violence and dis 
 placement of their particles, without a vivid evolu 
 tion of light and heat, and without producing at the 
 same time, all the furious effects peculiar to an 
 irresistible expansive force. The best conducting 
 substances, on the contrary, yielding as they do 
 almost immediately to the electrical transmission (p. 8), 
 at once quiet the disturbance without any such dis 
 astrous consequences. The transmission through 
 these is comparatively passive; and it is only in 
 some few instances to be hereafter considered, that 
 we find the small degree of resisting power they 
 possess, productive of any ill consequence, and then 
 only to the conducting substance itself, not to neigh 
 boring bodies. 
 
 Electrical conditions of a Thunderstorm. 
 
 We are indebted to Dr. Faraday s valuable and 
 most interesting series of Inquiries in Electricity,* 
 for very practical and sound views of the nature of 
 electrical action. These we shall now proceed to 
 apply to the conditions of a thunderstorm, which 
 will serve at the same time to explain them. 
 
 A thunderstorm may be considered, as the result 
 of a great electrical disturbance (pp. 4, 5), between 
 
 * Phil. Trans. 1881, to 1838. 
 
OF A THUNDERSTORM. 13 
 
 masses of vapor condensed in the atmosphere under 
 the form of clouds, a portion of the earth s surface 
 directly opposed to these masses, and the inter 
 mediate air ; the particles of which instead of allow 
 ing the disturbance to subside rapidly, virtually 
 maintain it up to a point, at which its force is no 
 longer to -be resisted. For example ; let the mass 
 of vapor P P (fig. 1), under the form of a cloud, be 
 
 FIG. 1. 
 
 o 
 
 o 
 
 
 
 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 
 
 o 
 
 
 
 
 A 
 
 
 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 o 
 
 
 
 
 
 o 
 
 
 
 o 
 
 
 
 
 
 N _____ _ N 
 
 supposed to contain active electricity, in consequence 
 of some of those changes in the condition of the 
 atmosphere, to which we have already alluded (p. 5). 
 Let N N be a portion of the earth s surface directly 
 opposed to these masses ; and A the intermediate 
 atmospheric particles. Now, Faraday has shown, 
 that in such a case as this, all these intermediate 
 particles assume a peculiar forced electrical state, 
 which he terms a polarized state. By way of typical 
 illustration, let a, 6, c (fig. 2), represent three of thes*e 
 consecutive particles, and suppose in their neutral 
 condition the electrical distribution of each particle 
 
14 
 
 ELECTRICAL CONDITIONS 
 
 to be uniform and equal, as indicated by the equali 
 zation of the dark and light squares. Now, when 
 these particles become placed under the influence of 
 a thunderstorm, as represented in figs. 1 and 4, there 
 would be no longer this uniform distribution. The 
 electricity of the particles would be compelled to 
 
 FIG. 2. 
 
 FIG. 3. 
 
 assume some new condition, such, for example, as 
 that shown in fig. 3 ; that is, we may consider the 
 electrical agency as being no longer distributed 
 according to a law of quiescence, but to be, as it 
 were, collected in the particle in some other way, 
 according to a law of disturbance. Suppose this 
 represented by the shadowed and light portions of 
 the particles a b r c (fig. 3), the dense portions being 
 constrained to appear in opposition to the light ones; 
 and let us further imagine, that this state consists in 
 a concentration of the electricity of each particle in 
 one of its opposite faces : in this case the particles 
 are said to be polarized. 
 
OF A THUNDERSTORM. 
 
 15 
 
 The immediate consequence of such a forced 
 state as this, is, that the electricity, rendered active 
 by any of the causes above mentioned (p. 5), propagates 
 through an insulating medium, such as the air, a 
 species of disturbance from particle to particle, which 
 at last arriving at distant conducting substances, 
 elicits an active electrical condition of such sub 
 stances, similar in effect to the primary disturbance, 
 but opposite in kind. This Faraday shows to be the 
 essence of that peculiar action of electrified on distant 
 bodies, termed induction. Thus, assuming by way 
 of illustration that P (fig. 4) were a cloud containing 
 
 FIG. 4. 
 
 a greater quantity of electricity, than it could support 
 in a state of quiescence, there would be immediately 
 
16 ELECTRICAL CONDITIONS 
 
 propagated through the intermediate particles of air 
 a, b, , d, &c., an induced action of this kind, the 
 intermediate particles a, 6, c, d, would be constrained 
 to assume the polarized state just mentioned. There 
 would be, according to the principle we have just 
 supposed, an alternate electrical condensation and ex 
 haustion P ;?, p n lt Pi riv &c., brought into play, which 
 at last reaching the earth s surface, would there elicit 
 an electrical force, N, exactly equal to the force at p, 
 but of an opposite or neutralizing quality ; so that 
 there would arise at N, by this kind of action, an 
 electrical exhaustion or displacement, just sufficient 
 to tranquillize the active accumulation at p. Now 
 it is of no consequence to the general result, which 
 of these opposite states P, N be supposed to reside in 
 the cloud P : we evidently may conceive the whole 
 chain (fig. 4) to exist without any actual change in its 
 condition, although the point K were imagined to be 
 the state of the cloud, and P that of the earth : the 
 intermediate particles a, 6, c, c?, would still become 
 polarized in the same way, but in an opposite sense. 
 We have only to conceive the figure reversed, and 
 this will be immediately apparent, the conducting 
 surfaces of the clouds and earth, being nothing more 
 than the terminating planes of a great intermediate 
 action, set up between them in a given direction.* 
 The induced disturbance at N, in the points im- 
 
 * Faraday has not unaptly termed insulating bodies dielectrics, 
 and the media, through which induction is sustained, dielectric 
 media, as expressive of substances through which electrical action 
 is propagated from particle to particle. i 
 
OF A THUNDERSTORM. 17 
 
 mediately opposed to the electrical cloud P, may be 
 considered as a species of reaction, and as giving ori 
 gin to a new force. We have, therefore, in every 
 disturbance of this kind, two forces present, exactly 
 equal and opposite to each other. These opposite 
 electrical states, have been imagined by some philoso 
 phers, to depend on the presence of two equally 
 powerful, but dissimilar agents, termed the vitreous 
 and resinous electricities, from the circumstance of 
 one of them being very commonly produced by the 
 excitation of vitreous, the other by the excitation of 
 resinous substances. There is not, however, any es 
 sential difference between them, so far as relates to 
 their action as physical forces ; and although, for the 
 sake of perspicuity, they may be considered as posi 
 tive and negative powers, or as positive and negative 
 electricities ; yet it is still to be remembered, that one 
 is as much a positive force as the other. It will be 
 immediately perceived, that the two forces must ne 
 cessarily exist both at the same time (p. 15) as at P, N 
 (fig. 4) : hence it is found impossible to charge com 
 mon matter with one of them, without the other ap 
 pearing somewhere, either in near or distant bodies,* 
 just as it is impossible to pull against a fixed point, 
 without eliciting in that point, an equal and oppo 
 site force. 
 
 Insulation Conduction Charge Discharge, &c. 
 
 These points being apprehended, we are immedi 
 ately prepared to receive the simple and lucid expla- 
 
 * FARADAY S Researches in Electricity, p. 365. 
 
18 INSULATION CONDUCTION 
 
 nation, which this eminent philosopher has given us, 
 of the terms, insulation, conduction, charge, dis 
 charge, &c. 
 
 We have already shown (p. 15) in what that pecu 
 liar arid wonderful influence, termed electrical induc 
 tion, may be said to consist, viz., a polarization, or 
 forced state of material particles, by which an action 
 is propagated, and made to appear in bodies however 
 distant. This we have conventionally, or typically, 
 represented in fig. 4, page 15 ; now supposing this 
 state of the particles could be maintained under all 
 circumstances, complete obstruction to the return of 
 the opposite forces to a state of quiescence would be 
 the result ; and we should arrive at perfect insulation 
 of these forces. This however is not the case, the 
 constrained state of the particles will not remain, ex 
 cept for a limited portion of time. Thus in fig. 4, 
 the positive force in p, will, if sufficient time be al 
 lowed, discharge into the negative force n of particle 
 a, the positive force of this particle into the negative 
 force ?i ! of particle 6, and so on to the negative force 
 N, until the whole disturbance is quieted, and the po 
 larization of the particles a, b, c, d, reduced. This 
 process constitutes conduction, and it always proceeds 
 more or less rapidty through every kind of substance; 
 the more rapidly however it can proceed, the better 
 the conducting power, and conversely, the less freely 
 it can proceed, the more perfect the insulating power 
 (p. 7). 
 
 Insulating bodies are, therefore, as already ob 
 served (p. 8), only conductors of a rigid and stubborn 
 
CHARGE DISCHARGE, ETC. 19 
 
 kind, the particles of which return to their normal 
 state so slowly, that for a limited portion of time, 
 they admit of being considered as exceptions to the 
 general law of conduction ; yet it is upon these bodies 
 that the process of induction depends, and upon this 
 process depends further, the state of things called 
 electrical charge, typically illustrated in fig. 4. As 
 long as the particles a, Z>, c, &c., can suffer the con 
 strained state in which they are placed (p. 12), so long 
 will the charge be maintained with but small loss ; 
 but when they can no longer resist the tendency of 
 the opposite electrical forces P, N, to combine through 
 out the series, we have immediately what Faraday 
 terms disruptive discharge that is to say, the parti 
 cles in fig. 1 (page 13), are .displaced and broken 
 through, with a greater or less degree of mechanical 
 violence. In this case, the electrical disturbance in 
 the particles having become as great as they can sus 
 tain, any tendency to further disturbance, instead of 
 inducing further change, subverts the whole- system, 
 and a violent reunion of the opposite electrical forces 
 instantly ensues. 
 
 Although such discharges are of a sudden and 
 violent character, and productive of damage to bodies 
 through which they pass, yet they occasionally be 
 come so modified by various circumstances, as to as 
 sume a more progressive and quiet form, often free 
 from any attendant danger whatever. 
 
 If a pointed metallic rod, K (fig. 5), project freely 
 into a charged system, p, R, N, from one of its termi 
 nating planes N, the polarized particles immediately 
 
20 
 
 INSULATION CONDUCTION 
 
 at the extremity of the rod have the forced condition 
 (p. 12) so highly exalted, that it terminates in discharge 
 upon the next or more remote particles, the electrical 
 condition of which is less intense. The consequence 
 
 of this is, a luminous brush of beautifully colored 
 light, attended by a sort of roaring noise. This 
 brush discharge may be considered as taking place 
 between a good and bad conductor : it is, in fact, an 
 intermitting series of electrical sparks between metal 
 and air ; but in such rapid succession as to convey 
 the idea of a continuous stream. The discharge in 
 this case always commences at the root of the brush, 
 and is complete at the point of the rod, before the 
 more distant particles attain the same intensity: 
 hence the discharge is progressive, and occupies a 
 sensible time. 
 
 Brush discharge, by means of pointed or angular 
 
CHARGE DISCHARGE, ETC. 21 
 
 bodies, will, under certain conditions of conduction, 
 assume the appearance of a luminous star, especially 
 when it is proceeding from a negative or resineus 
 electricity (pp. 16, 17). Hence the observation, that 
 electrical discharge from a pointed conductor, is at 
 tended by a luminous brush of rays, but toward a 
 pointed conductor by a star of light. 
 
 When the air in contact with a metallic rod is 
 becoming rapidly charged, we have another species 
 of discharge, termed glow discharge ; that is to say, 
 the metal in contact with the electrified particles be 
 comes covered with a glow of lambent light, pro 
 ducing a beautiful effect. 
 
 Dr. Watson, in the 48th volume of the Phil. 
 Trans., has collected out of ancient history several 
 interesting notices of these electrical appearances. 
 Thus Pliny, in his Natural History, tells us " stars 
 settled on the sail-yards and masts of ships with an 
 audible sound : also on the spears of soldiers." 
 Seneca, again, in his Natural Questions says, that the 
 " spears seemed to be on fire in the Koman camp." 
 
 Similar appearances are mentioned by Caesar and 
 Livy. 
 
 In more recent periods, we find repeated notices 
 of similar natural phenomena. They are called by 
 the French and Spaniards, St. Helmo s, or St. Elmo s 
 fires ; by the Italians, the fires of St. Peter and St. 
 Nicholas. On ship-board in this country, sailors 
 call them comazants. "In the night (says the 
 Count de Forbin) we saw on different parts of the 
 ship above thirty St. Helmo s fires ; one of them was 
 
22 INSULATION CONDUCTION 
 
 more than a foot and a half in height ; its noise re 
 sembled that of fired gunpowder."* 
 
 Captain Waddel, of the merchant ship Dover, met 
 with a heavy electrical storm in January, 1748 : he says, 
 "Sundry very large comazants (as we call them) 
 settled on the spindles, and burnt like very large 
 torches."f The ship was soon after struck by light 
 ning. Captain Fanshawe, E. N., observed on board 
 his Majesty s ship Newcastle, in May, 1821, luminous 
 appearances "resembling the flame of a gas-light 
 on the extremities of the masts ; the lights were vi 
 sible " sometimes on one mast, sometimes on an 
 other, and sometimes on all of them." The ship 
 was sailing from Bermuda to Halifax, the weather 
 unsettled and squally, with a " mass of black clouds 
 close astern," vivid lightning and thunder occa 
 sionally. 
 
 At Plauzet, in France, the three-pointed extre 
 mities of the cross of the steeple, always appeared sur 
 rounded with a body of flame during great storms 
 of lightning.f 
 
 M. Toscan, the librarian of natural history in 
 the Botanic Gardens in Paris, witnessed, in May, 
 1803, during the presence of heavy black clouds, a 
 vivid glow of electrical light on a bent iron bar 
 surrounding a wall in the gardens ; it gave him the 
 idea of a large ball of fire of a foot in diameter, and 
 lasted eighteen seconds. This glow discharge pre- 
 
 * Phil. Trans., vol. xlviii. 
 
 f Phil. Trans., voL xlvi. p. 3. 
 
 \. PRIESTLEY S History of Electricity, p. 273. 
 
CHARGE DISCHARGE ETC. 23 
 
 ceded a heavy stroke of lightning on the house 
 about six feet distant.* 
 
 The fact of discharge occurring between bad 
 and good conductors, in such way as to produce a 
 spark, leads in some degree to an explanation of 
 certain electrical explosions observed to occur, al 
 though rarely, in an apparently serene sky. Thus 
 his Majesty s ship Dictator is said to have been struck 
 and damaged by a fire-ball at Martinique, in the 
 year 1794, during fine weather. In this case the 
 surface of the sea may have discharged upon the 
 nearest particles of air, which, by some of those 
 changes so frequently taking place in the atmo 
 sphere had become polarized. It is not improbable, 
 that on the same principle, luminous electrical dis 
 charges may occur between particles of polarized 
 air in different states of intensity, producing those 
 progressive appearances more especially called me 
 teors. These have all the characters of a dense elec 
 trical discharge propagated, as it were, from particle 
 to particle through a considerable space ; and pro 
 bably dragging into its path, light vapors and in 
 flammable matter floating in the atmosphere, and 
 increasing by their intense ignition the luminous 
 and highly brilliant appearance which such meteors 
 exhibit. 
 
 Identity of common Electricity with the agency of 
 Lightning. 
 
 The years 1745 and 1746 mark an important 
 
 * GILB. Annal, xiii., p. 484. 
 
24 IDENTITY OF COMMON ELECTRICITY 
 
 era in the history of physical science. Von Kleist, 
 dean of the Cathedral of Kamin, and some Dutch 
 philosophers in the university of Leyden, in endea 
 voring to confine electricity within the limits of a 
 small phial, discovered a method of accumulating it 
 on glass to a most unprecedented degree, and of 
 subsequently discharging it through bodies, in such 
 a way as to produce the most powerful and aston 
 ishing effects. By these discharges a fearful sen 
 sation could be impressed on living animals even 
 life itself destroyed ; metallic substances could be 
 violently heated, fused, and ignited ; inflammable 
 bodies set on fire, and the most compact substances 
 scattered in pieces, as if acted on by a violent ex 
 pansive force. When, therefore, the cause of light 
 ning became identified with that of ordinary elec 
 tricity, with the very element, as it were, by which 
 such effects were produced ; and the gigantic attempt 
 of Franklin (about seven years afterwards) actually 
 to draw electricity from the clouds, and appropriate 
 it in a similar way to the purpose of experiment, 
 had fully succeeded, then it was, that these artifi- 
 ficial electrical accumulations and discharges ac 
 quired a more than ordinary interest, as furnishing 
 us with a valuable means of investigating by minor 
 experiments, the laws and operations of the great 
 discharge in thunderstorms. 
 
 The identity of common electricity and lightning, 
 although not fully verified until the year 1752, had 
 nevertheless been long suspected. Mr. Gray, an 
 English electrician, observes (Phil. Trans, for 1735), 
 
WITH THE AGENCY OF LIGHTNING. 25 
 
 that " the electric fire seems to be of the same nature 
 with that of thunder and lightning,"* and the cele 
 brated Abbe Nollet, in his Legons de Physique, acutely 
 describes many great points of resemblance between 
 them. "If any one (he observes) should take upon 
 him to prove from a well connected comparison of 
 phenomena, that thunder is, in the hands of nature, 
 what electricity is in ours, that the wonders we ex 
 hibit at our pleasure are little imitations of those 
 great effects which inspire us with awe, and that the 
 whole depends upon the same mechanism, if it is to 
 be demonstrated that a cloud prepared by the action 
 of winds, by heat, &c., is an electrized body, I avow 
 this idea, well supported, wguld be to me a source 
 of great delight." 
 
 At length Franklin in America, and several phi 
 losophers in France, conceived the grand thought of 
 bringing the element of lightning out of the atmo 
 sphere, by means of pointed conducting bodies ; and 
 in the year 1752 electrical sparks were drawn from 
 the clouds. Tired of waiting for the erection of a 
 spire at Philadelphia, on which he proposed to fix a 
 pointed rod of iron, the American philosopher had 
 recourse to a common kite, as affording an immedi 
 ate and ready access to the region of lightnings. The 
 kite had a pointed wire, and the twine which held it 
 was attached to an insulating cord of silk. A passing 
 shower opportunely wetted the twine, and increased 
 
 * Dr. Wall also observes, Phil Trans., vol. xxvi., that the crack 
 ling sound and light produced by the excitation of amber represents 
 in some degree thunder and lightning. 
 2 
 
26 IDENTITY OF COMMON ELECTRICITY 
 
 its conducting power, at the same moment electrical 
 sparks were drawn from a key hung on the extrem 
 ity of the kite-string. 
 
 In the mean time, Dalibard and Delor, both zeal 
 ous partisans of Franklin, had drawn electrical sparks 
 from the clouds at Paris and in its vicinity, by 
 means of pointed iron rods, forty feet in length, ele 
 vated upon some of the highest ground they could 
 find ; and thus was verified one of the most interest 
 ing and important theories to be found in the history 
 of physics. 
 
 Dr. Franklin, in remarking on the similarity be 
 tween common electricity and lightning, cautions his 
 readers against any degree of disparity of effect as 
 an argument against the identity of these powers. 
 It is no wonder, he says, that the effects of the one 
 so far surpass the other. " If two gun-barrels, when 
 electrified, will strike at two inches distance, and 
 make a loud report, at how great a distance may 
 10,000 acres of electrified cloud strike, and how loud 
 must be that crack ?" 
 
 The great. points of coincidence between the com 
 mon electric discharge and lightning may be thus 
 specified : 
 
 Flashes of lightning are frequently waving and 
 crooked, of a zig-zag or forked appearance, some 
 times diffuse and colored the same is true of sparks 
 drawn from the ordinary electrical machine. 
 
 Lightning most commonly falls on elevated or 
 pointed objects the same is true of electricity. 
 
 Lightning seizes on the readiest and best line of 
 
WITH THE AGENCY OF LIGHTNING. 27 
 
 transit in its course to the earth the same is true of 
 the common electrical discharge. 
 
 Lightning burns up various kinds of matter 
 fuses and ignites metallic bodies the same is true 
 of the electrical discharge. 
 
 Lightning rends brittle substances, and scatters 
 various kinds of matter, as if they were acted on by 
 a violent expansive force such is also the case with 
 electricity. 
 
 Lightning impresses on living animals a peculiar 
 nervous shock, and sometimes destroys life this is 
 also the case with electricity. 
 
 Lightning reverses, destroys, or gives magnetic 
 polarity to steel such is also the result of powerful 
 electrical discharges. 
 
 When these coincidences are considered, together 
 with the fact that electricity may be drawn out of 
 the clouds and air, and applied to produce precisely 
 the same effects as those resulting from a common 
 electrical machine, it becomes quite evident that the 
 cause, whatever it be, of ordinary electrical pheno 
 mena, is identical with that of lightning; conse 
 quently we arrive at the important deduction, that 
 common electricity and lightning are subject to the 
 same laws, a deduction which cannot be too forci 
 bly insisted on, involving as it does the most valua 
 ble practical consequences. 
 
 Nature of ordinary Electrical Arrangements producing 
 
 Artificial Lightning. 
 The great discovery of the electrical jar, to which 
 
28 ORDINARY ELECTRICAL ARRANGEMENTS 
 
 we have adverted (p. 23), involves, in fact, all the 
 conditions of a thunderstorm, the disruptive dis 
 charge from the jar being the same in effect as thun 
 der and lightning. This will be immediately per 
 ceived by referring to what has been already ad 
 vanced on this subject (pp. 12, 15), where it may 
 be seen that the conditions there represented are re 
 ducible to the separation of two conducting planes, 
 p, N (fig. 1), by an intermediate insulating substance 
 A; one of the conductors, p, being limited, the other, 
 N, of indefinite extent. Now, to complete such a 
 system artificially, we have only to attach two con 
 ducting surfaces, P, N (fig. 6), to the opposite sides 
 of a square of glass, A, B, leaving about an inch of 
 
 FIG. 6. 
 P 
 
 the glass clear and projecting between the two. If 
 such a system be placed on a conducting base, com 
 municating with the earth, it is evident we have a 
 limited and insulated conductor, p, opposed to a con 
 ductor, N, of indefinite extent. Directly we charge 
 this system on the insulated surface, P, the two con 
 ducting surfaces, p N, become the terminating planes 
 of a great electrical action, and the particles of the 
 glass become polarized by induction (p. 15) : hence 
 this system is precisely the same as that represented 
 in fig. 4. The nature of the insulating substance 
 
PRODUCING ARTIFICIAL LIGHTNING. 29 
 
 between the planes, does not in any way interfere 
 with the conditions of this arrangement, nor does its 
 thickness, because induction goes on at all distances. 
 Faraday traced it from a small electrified ball in 
 the middle of a room to the walls, twenty -six feet 
 distant.* It takes place, however, with the same 
 constraining force, more readily according as the ex 
 tent of the intervening insulation is lessened. Hence 
 it is, that with a small thickness of glass we obtain 
 a very intense action, the density and compactness 
 of the glass furnishing a resistance, sufficient to main 
 tain the particles in their polarized condition. This 
 is not the case with a gaseous insulation, such as air, 
 the particles of which soon break down at small 
 distances, under the reactive force of the opposite 
 electrical powers (pp. 15, 19). 
 
 It is, however, requisite here to understand, that 
 disruptive discharges from this arrangement are gen 
 erally obtained by neutralizing the forces through a 
 side circuit of conductors ; that is to say, instead of 
 
 FIG. 7. 
 
 allowing the intermediate glass to become broken 
 down by the force between the conducting planes, P } 
 
 * Researches in Electricity, p. 411. 
 
80 ORDINARY ELECTRICAL ARRANGEMENTS 
 
 N, as suppbsed in figs. 1 and 4, we discharge the sys 
 tem through a side circuit, abode (fig. 7). This, 
 however, is of no consequence to the result of this 
 experiment, because the laws of such discharges, by 
 which the system is reduced to electrical quiescence, 
 remain the same ; and any substance exposed to the 
 effects of the discharge in the interval, c, would be 
 affected in precisely the same way as if it were in 
 the interval, p, N, immediately between the termina 
 ting planes. 
 
 Thus, suppose P N (fig. 8), to be the terminating 
 planes of a great electrical disturbance in an interval 
 
 FIG. 8. 
 
 p 
 
 of air. Imagine a conducting path suddenly opened, 
 and the system discharged : it is clear that whether 
 such a path were opened immediately between the 
 planes as at P a N, or at the edge of the planes as at 
 n b PJ the result must be the same. Now, imagine 
 the conducting circuit at the edge of the planes to 
 be curved into the form n o p, still this could not 
 possibly affect the law of the discharge in the circuit, 
 but this last is the case in question. Suppose, 
 further, we had made a disruptive interval in this 
 discharging conductor in any point of it, as 0, 5, a, 
 
PRODUCING ARTIFICIAL LIGHTNING. 31 
 
 still the result of the discharge in such an interval 
 would remain invariable ; consequently we may as 
 sume any one of the- three paths of discharge, P a N, 
 n b p, n o p, to be a casual association of bad and 
 good conductors, as in the case of a building, with 
 out in any way affecting the law of the discharge 
 through them. Therefore let the immediate position 
 of the line of discharge be what it may, whether 
 immediately between the planes P, N, or extending 
 without them as at n o 6, or whether interrupted by 
 a large interval P a, n 6, n o, still the laws regulating 
 the neutralization of the opposite electrical forces 
 through such a disjointed circuit must be always the 
 same. 
 
 Then, with respect to the immediate mechanical 
 form or arrangement of such a system, that is also a 
 matter of indifference; we may make the system 
 cylindrical if we please, and hence the immediate 
 application of the principle to the Leyden experi 
 ment or electrical jar. This piece of electrical appa 
 ratus in its improved state, consists of two conducting 
 surfaces P, N (fig. 9), pasted on the opposite sides of 
 a glass jar, a portion of the glass d d being left clear 
 and projecting between them. When electricity is 
 communicated to the interior insulated surface P, by 
 means of a rod a c, the outer surface N resting on the 
 ground, the whole system becomes charged as in the 
 former case, and may hence be in like manner dis 
 charged by means of a curved metallic wire n &, and 
 if we connect the charging rods of many such jars, 
 all resting on a common conducting base, we may 
 
32 
 
 ORDINARY ELECTRICAL ARRANGEMENTS 
 
 charge and discharge the whole together, as one 
 great system of enormous power, and produce 
 effects approaching to those of lightning. With the 
 great battery in the Tylerian Museum at Haerlem, 
 which exposed 225 square feet of insulated metallic 
 surface d, Yan Marum gave polarity to stee* bars nine 
 
 FIG. 9. 
 a b 
 
 O 
 
 X 
 
 / 
 ; 1 P 
 
 
 
 P 
 
 c 
 
 
 inches long, nearly half an inch wide, dtid one-twelfth 
 of an inch thick. A piece of box-wood four inches 
 in diameter and four inches in length was rent by it 
 in pieces. It melted readily various metals, and dis 
 persed them in all directions. An iron wire twenty- 
 five feet long, and about T J -th of an inch in diameter, 
 fell under the shock, into red hot balls dispersing in 
 all directions. A piece of tin wire eight inches long, 
 and one-eighteenth of an inch in diameter, disappear 
 ed in a cloud of blue smoke, throwing down red-hot 
 globules of tin, which repeatedly rebounded from a 
 
PRODUCING ARTIFICIAL LIGHTNING. 33 
 
 piece of paper beneath it.* In the course of similar 
 experiments by Mr. Brook, he says, "the report was 
 so very load, that our ears were stunned, and the 
 flash of light so very great, that my sight was quite 
 confused for a few seconds." 
 
 The electrical machine employed by Van Marum 
 consisted of two circular plates of glass, each five 
 feet five inches in diameter : these were set on the 
 same axis, and were rendered electrical by revolving 
 with friction between eight cushions, each about 
 fifteen inches long, and two inches wide. The 
 power of this splendid instrument was such, that 
 bodies at forty feet distance were sensibly influenced ; 
 pointed wires became tipped with a star of light 
 at twenty-eight feet distance (p. 19), and a powerful 
 current of brilliant light two feet or more in length, 
 crooked, and darting forth luminous brushes into the 
 air, was obtained by presenting a metallic ball in con 
 nection with the earth, to its great conductor. A 
 single spark melted a considerable length of gold- 
 leaf, and fired various kinds of combustibles. 
 
 We have thought it not unimportant to notice 
 these results, as having a direct bearing on the great 
 question of the defence of buildings from lightning. 
 For since the accumulation of electricity by artificial 
 means may be carried to an almost indefinite extent, 
 and is equally manageable, whatever may be the 
 extreme limit of force we choose to assign to such 
 accumulation, it necessarily follows that discharges 
 
 * Roz. xxxiii. and Phil. Mag., vol. viii. ; NICH. ii. 527. 
 2* 
 
34 VARIOUS PHENOMENA OF 
 
 of atmospheric electricity may be quite as easily 
 directed, by a judicious and scientific arrangement 
 of conducting bodies ; such discharges being in fact, 
 nothing more than the same force also resulting from 
 a species of electrical machine, and accumulated in a 
 similar way, by means of an apparatus of a perfectly 
 similar kind. The vapory masses of the clouds, 
 opposed through the intermediate air to the surface 
 of ground or sea, constitute a battery of enormous 
 power. The circumstance of the coatings of the jar 
 being metallic, whilst those in nature consist of 
 water, is a difference of no moment whatever ; espe 
 cially when we consider that the original experiment 
 of the Dutch philosophers, consisted in the electrifi 
 cation of water inclosed in a small phial, from which 
 they obtained so great a shock, as to induce one of 
 them to say that he would not again receive it for 
 the whole kingdom of France. 
 
 Various Phenomena of Lightning and Thunder. 
 
 The identity of ordinary electrical discharges with 
 the phenomena of thunder and lightning being thus 
 satisfactorily shown, we have now merely to consider 
 some of those modifications of the effect, characteristic 
 of these great natural operations. In the first place, 
 it is to be observed, that when the discharge takes 
 place very close to the observer, the effect is a brilliant 
 vivid light of momentary duration, intolerable to the 
 eye, and attended by a terrific and sudden whizzing 
 crash, as if ten thousand porcelain jars had fallen on 
 a stone pavement, and were smashed in pieces. 
 
LIGHTNING AND THUNDER. 35 
 
 When, however, some considerable distance is inter 
 posed, the light is more tolerable, and precedes the 
 crash by a sensible time ; in this case the noise begins 
 to soften down into a sort of reverberating roar ; at 
 still greater distances the reverberations are taken 
 up, and bandied about between the irregular forms 
 of the distant clouds and the surface of the earth, pro 
 ducing what has been termed, in common language, 
 peals of thunder. A similar effect ensues on the 
 earth s surface, during the discharge of cannon, where 
 surrounding objects present irregular sources of re 
 verberation: on the sea, where so few obstacles to 
 the diffusion of sound exist, distant thunder regular 
 ly dies away in a sort of sullen silence. The distance 
 of the point of discharge, may be estimated by the 
 time which elapses between the flash of lightning 
 and the thunder ; since for small distances, the pro 
 gress of light may be taken as instantaneous : sound, 
 on the contrary, has a more sensible duration, being 
 propagated through the air, at the rate of eleven 
 hundred feet in a second. It may be here remarked, 
 that an essential distinction exists between the light of 
 lightning, for which, as Franklin observes, we want 
 an appropriate term, and the presence of the electrical 
 agency itself. 
 
 Arago divides the phenomena of lightning into 
 three classes. In the first he places those luminous 
 discharges characterized by a long streak of light, 
 very thin, and well defined at the edges : they are 
 not always white, but are sometimes of a violet or 
 purple hue; they do not move in a straight line, 
 
36 VARIOUS PHENOMENA OF 
 
 but have a deviating track of a zig-zag form. They 
 frequently divide in striking terrestrial objects, into 
 two or more distinct streams, but invariably proceed 
 from a single point. The Abbe Eichard witnessed 
 a discharge of this kind descend from a cloud, and 
 divide upon two separate objects on coming near the 
 earth.* We have instances, in the damage done to 
 our shipping, of the trifurcation of lightning, in 
 which the three masts of a ship have all been struck 
 by the same discharge. This result ensued in His 
 Majesty s ship Implacable, under the command of Sir 
 George Cockburn, in July, 1810, near the Isle of 
 Wight. The fore and mizzen topgallant-masts were 
 shivered, and traces of the discharge were left on the 
 main-mast. 
 
 Under the second class, Arago has placed those 
 luminous effects not having any apparent depth, but 
 expanding over a vast surface : they are frequently 
 colored red, blue, and violet; they have not the 
 activity of the former class, and are generally con 
 fined to the edges of the cloud from which they 
 appear to proceed. 
 
 The third class comprises those more concentrat 
 ed masses of light, which he has termed globular 
 lightning. The long zig-zag and expanded flashes, 
 exist but for a moment, but these seem to endure 
 for many seconds : they appear to occupy time, and 
 to have a progressive motion. 
 
 It is more than probable, that many of these 
 
 * ffistoire Naturellc de I Air ct des Meteores. 
 
LIGHTNING AND THUNDER. 37 
 
 phenomena are at least reducible to the common 
 progress of the disruptive discharge, modified by the 
 quantity of passing electricity, the density and con 
 dition of the air, and the brilliancy of the attendant 
 light. When the state of the atmosphere is such, 
 that a moderately intense discharge can proceed in 
 an occasionally deviating zig-zag line, the great nu 
 cleus, or head of the discharge, becomes drawn out 
 as it were, into a line of light visible through the 
 whole track ; and if the discharge divides on ap 
 proaching a terrestrial object, we have what sailors 
 call forked lightning. If it does not divide, but ex 
 hibits a long rippling line, with but little deviation, 
 then they call it chain lightning. What sailors term 
 sheet lightning, is the light of a vivid discharge re 
 flected from the surfaces of distant clouds, the spark 
 itself being concealed by a dense intermediate mass 
 of cloud, behind which the discharge has taken 
 place. In this way an extensive range of cloud may 
 appear in a blaze of light, producing a truly sublime 
 effect. The appearance termed globular lightning, 
 may be the result of similar discharges ; it is no 
 doubt always attended by a diffusely luminous track, 
 this may, however, be completely eclipsed in the 
 mind of the observer, by the great concentration and 
 density of the discharge, in the points immediately 
 through which it continues to force its way, and 
 where the condensation of the air immediately be 
 fore it is often extremely great. It is this intensely 
 illuminated point which gives the notion of globular 
 discharge ; and it is clear, from the circumference of 
 
38 APPEARANCES TERMED FIRE-BALLS. 
 
 air which may become illuminated, the apparent 
 diameter will be often great. Mr. Heartier, of Ply 
 mouth, once witnessed a discharge of lightning of 
 this kind on the Dartmoor hills, very near him. 
 Several vivid flashes had occurred, before the mass 
 of clouds approached the hill on which he was stand 
 ing : before he had time to retreat from his danger 
 ous position, a tremendous crash and explosion burst 
 close to him. To use his own words, " the spark had 
 the appearance of a nucleus of intensely ignited mat 
 ter, followed by a flood of light ; it struck the path 
 near me, and dashed with fearful brilliancy down its 
 whole length, to a rivulet at the foot of the hill, 
 where it terminated." 
 
 Appearances termed Fire-Bails. 
 
 A great deal has been said relative to these ap 
 pearances, and some doubts have been entertained 
 of their real existence as mere balls of electrical 
 light. Nevertheless the evidence of the existence 
 of a form of disruptive discharge, faithfuly convey 
 ing to the observer such an impression, is beyond 
 question. A curious instance is given by Mr. Chal 
 mers whilst on board the Montague, of seventy -four 
 guns, bearing the flag of Admiral Chambers. In 
 the account read at the Eoyal Society,* he states that 
 " November 4th, 1749, whilst taking an observation 
 on the quarterdeck, one of the quartermasters re 
 quested him to look to windward ; upon which he 
 
 * Phil Trans., vol. xlvi., p. 366. 
 
APPEARANCES TERMED FIRE-BALLS. 39 
 
 observed a large ball of blue fire rolling along on 
 the surface of the water, as big as a mill-stone, at 
 about three miles distance. Before they could raise 
 the main-tack, the ball had reached within forty 
 yards of the main-chains, when it rose perpendicu 
 larly with a fearful explosion, and shattered the main- 
 topmast in pieces." In an account of the fatal ef 
 fects of lightning, in June, 1826, on the Malvern 
 Hills, when two young ladies were struck dead, it is 
 stated that the electric discharge "appeared as a 
 mass of fire rolling along the hill towards the build 
 ing in which the party had taken shelter."* 
 
 The great number of accounts of such appear 
 ances, and the remarkable coincidences in them all, 
 extending as they do through nearly a whole cen 
 tury, and consequently given by observers in no way 
 connected with each other, leave not the least doubt 
 of their existence. M. Deslandes transmitted to the 
 Academy of Science in Paris an account of a terrible 
 thunderstorm in Brittany, in April 1718, which 
 completely destroyed a church near Brest. In this 
 account it is stated that the damage was done by 
 three large globes of fire of three feet and a half in 
 diameter, which fell at once on the spire.f 
 
 It is by no means easy to explain these appear 
 ances on the principles applicable to the ordinary 
 electric spark : the amazing rapidity with which this 
 proceeds, and the momentary duration of the light 
 
 * Loyd s Evening Post. 
 \Annuaire pour 1838, p. 259. 
 
40 APPEARANCES TERMED FIRE-BALLS. 
 
 (p. 8), renders it almost a matter of impossibility that 
 the discharge should appear under the form of a ball 
 of fire ; it would be a transient line of light : we must 
 look, therefore, to some other source for an explana 
 tion of these appearances. 
 
 Now it is not improbable, that in many cases in 
 which distinct balls of fire of sensible duration have 
 been perceived, the appearance has resulted from the 
 species of brush or glow discharge already described 
 (p. 19), and which may often precede the main 
 shock : the ball of fire, observed by M. Toscan at 
 the Botanic Gardens in Paris, was evidently a result 
 of this kind. In short, it is not difficult to conceive, 
 that before a discharge of the whole system takes 
 place, that is to say, before the constrained condition 
 of the dielectric particles of air intermediate between 
 the clouds and earth (p. 15) becomes as it were over 
 turned, the particles nearest one of the terminating 
 planes, or other bodies situate on them, may begin 
 to discharge upon the succeeding particles, and make 
 an effort to restore the neutral condition of the sys 
 tem by a gradual process. Such was doubtless the 
 case in the instances given by M. Deslandes and M. 
 Toscan. 
 
 If therefore we conceive the discharging particles 
 to have progressive motion from any cause, then we 
 shall immediately obtain such a result as that ob 
 served by Mr. Chalmers on board the Montague (p. 
 38), in which a large ball of blue fire was observed 
 rolling on the surface of the water, towards the ship 
 
APPEARANCES TERMED FIRE-BALLS. 41 
 
 from to windward. This was evidently a sort of glow 
 discharge, or St. Helmo s fire, produced by some of 
 the polarized atmospheric particles yielding up their 
 electricity to the surface of the water, much in the 
 same way, as, in the appearance observed by M. Tos- 
 can, the stationary cloud did on the land. The 
 clouds, however, were here in rapid motion, the 
 ship at the time being under topsails and courses 
 only, in consequence of the strength of the wind : 
 the discharging particles, therefore, had motion to 
 wards the ship, the rate of which appears, from the 
 account to correspond with the velocity of the breeze. 
 On nearing the ship, the point of discharge became 
 transferred to the head of the mast ; and the striking 
 distance being thus diminished, the whole system re 
 turned to its normal state (p. 12), that is to say, a 
 disruptive discharge ensued between the sea and the 
 clouds (p. 15), producing the usual phenomena of 
 thunder and lightning, termed by the observers, the 
 " rising of the ball through the mast of the ship." 
 The fatal occurrence on the Malvern Hills (p. 39) is 
 another instance of the same kind. A similar effect 
 is described in the Phil. Trans, for 1773, in which a 
 ball of light appeared in the parlor of a house struck 
 by lightning at Steeple Ashton. The ball is de 
 scribed as being of u the size of a sixpenny loaf, and 
 surrounded with a dark smoke," and is said " to have 
 burst with a loud noise." This too was evidently a 
 species of brush or glow discharge (p. 21), preceding 
 the stroke of lightning which damaged the house. 
 It is therefore highly probable, that all these ap- 
 
42 SULPHUROUS ODOR OF 
 
 pearances so decidedly marked as concentrated balls 
 of fire, are produced by the glow or brush discharge 
 producing a St. Helmo s fire in a <iven point or 
 points of the charged system (p. 15), previously to 
 the more general and rapid union of the electrical 
 forces; whilst the greater number of discharges de 
 scribed as globular lightning, are, as already ob 
 served, most probably nothing more than a vivid 
 and dense electrical spark in the act of breaking 
 through the air, which, coming suddenly on the 
 eye, and again vanishing in an extremely small por 
 tion of time, has been designated a ball of light. 
 Thus in a thunderstorm which damaged a house at 
 Eastbourne, in Sussex, in September 1781, balls of 
 fire were said to dart from the clouds into the sea. 
 These were evidently common electrical sparks seen 
 at a distance ; for when the lightning struck the 
 house, " multitudes saw the meteor dart in a right 
 line over their heads, and all agreed that the form 
 and flame were exactly like that of an immense sky 
 rocket."* 
 
 Sulphurous Odor of the Electric Discharge. 
 
 There is one circumstance noticed by the cele 
 brated Italian philosopher, Beccaria, which must not 
 be lost sight of, as having doubtless great influence 
 over these appearances, viz., the tendency of the 
 electrical discharge to drag into its path light con 
 ducting substances, which can facilitate its progress, 
 
 * Phil. Trans, for 1781, p. 42. 
 
THE ELECTRIC DISCHARGE. 43 
 
 and by which it is enabled to strike through dis 
 tances considerably greater than would otherwise be 
 traversed. Thus traces of smoke, free vapor, or any 
 other conducting matter floating in the air, will fre 
 quently determine the course of lightning, and not 
 only determine it as to direction, but greatly modify 
 its appearance. A heated or whirling column of air, 
 such as is sometimes seen to arise even in a tranquil 
 state of the weather, would produce a similar effect 
 through its interior and rarefied portion ; and there 
 is little doubt that conducting matter, when dragged 
 into the path of lightning, would be intensely heated 
 and decomposed. Beccaria once received an electric 
 shock through the fumes of nitric acid, which be 
 came concentrated and driven into his thumb pro 
 ducing a small round hole ; and Priestley found that 
 a discharge could be produced, by the dispersion of 
 a drop of water which hung on a brass rod commu 
 nicating with the inside of his battery. 
 
 The transfer and ignition of ponderable matter 
 through the track of electrical discharge, may be ad 
 duced to explain, in some degree, the suffocating sul 
 phurous odor so frequently observed at the time of 
 heavy strokes of lightning : on ship-board more es 
 pecially, when great damage has arisen, and the elec 
 trical discharge has exploded below decks, this sul 
 phurous smell is described as quite suffocating. In 
 the case of the Montague, just cited (p. 38), it is said 
 of this odor, that " the ship seemed to be nothing 
 but sulphur." From whence this arises is still an 
 interesting problem in physics. There are many 
 
44 ARTIFICIAL DISRUPTIVE DISCHARGES. 
 
 facts, which favor the idea of various kinds of matter 
 being dragged and transported into the track of the 
 electrical discharge, either immediately from the 
 body of the earth, or from the atmosphere in which 
 they are often found ; and it is not impossible in this 
 way to explain those apparently solid balls of fire 
 termed more especially meteors; that vapors of va 
 rious kinds may greatly modify and direct disruptive 
 discharge, is unquestionable, and hence give rise to 
 those long, truncated appearances of flame frequently 
 observed in discharges of lightning. It would be 
 trespassing on the limits of this work, to enter at 
 length upon the theory of meteors, or upon those 
 chemical views which some able philosophers have 
 entertained, of the nature of the odor emitted by the 
 electrical discharge ; it may perhaps be sufficient for 
 our present purpose to keep it in view, without an 
 elaborate detail of its possible causes.* 
 
 Artificial Disruptive Discharges. 
 
 The luminous appearances observable in the great 
 and terrible discharges of lightning, may be com 
 pletely obtained by artificial means, giving rise to 
 
 * Mr. Benjamin Cook, P. R. S., states, that after a night of vivid 
 lightning, with thunder, an oblong ball, of a bright yellow color, 
 and frosted over with fine yellow crystals, was found in a meadow 
 far from any house, and in a perfectly undisturbed surface of ground. 
 The ball appeared quite fresh. The crystals were easily displaced, 
 and the matter of the ball was principally sulphur. It burned with 
 mild sulphurous flames. Phil. Trans., vol. xl. 
 
ARTIFICIAL DISRUPTIVE DISCHARGES. 45 
 
 experiments of a highly instructive kind. The con 
 ditions which modify the extent and appearance of 
 the electrical discharge, produced artificially, are the 
 form and extent of the conductors between which 
 the disturbance has taken place, the quantity of ac 
 cumulated electricity, the intensity of the charge, 
 and the nature and density of the medium through 
 which it forces its way. Between round and even 
 surfaces, of considerable extent as compared with the 
 amount of electricity accumulated, the sparks, under 
 common states of the air, are short and dense, ap 
 proaching in appearance globular lightning: and 
 this is true in respect of electricity passing between 
 ^Jmy two parallel surfaces, and is even applicable to 
 the conditions of the discharge of the electrical jar. 
 The opposed conductors p N (fig. 7), so influence the 
 form, appearance, and dimensions of the spark, that 
 we cannot obtain under common circumstances, 
 through the neutralizing circuit a b c d e, a more ex 
 tensive discharge than could take place, supposing it 
 to have occurred immediately between P N, the ter 
 minating planes themselves. Short dense discharges 
 are in each case produced, approaching in appearance 
 to many of those in nature, called by sailors, fire 
 balls. 
 
 By changing the disposition and form of the 
 conductors, we obtain longer and more diffuse 
 sparks, of a zig-zag and waving character, which 
 frequently bifurcate, and otherwise divide, pro 
 ducing appearances similar to those termed by mari 
 ners, forked and chain lightning. All this greatly 
 
46 ARTIFICIAL DISRUPTIVE DISCHARGES. 
 
 depends on the activity of the charge, which again 
 varies with the extent of surface upon which it 
 passes; the activity of electricity disposed on sur 
 faces varying in dimensions, being in an inverse 
 duplicate ratio of the surface, the quantity being 
 constant;* that is to say, a given quantity of elec 
 tricity collected on a double extent of conducting 
 surface, has only one-fourth the activity on a treble 
 extent only one-ninth and so on. Hence an elec 
 trical disturbance which, between terminating planes 
 of large dimensions, would be comparatively quies 
 cent, becomes active and unruly between planes of 
 much less extent. When large quantities of elec 
 tricity, therefore, press upon small surfaces, 
 spark is elongated and spiteful in its character ; and 
 if these be indefinitely reduced to mere points, the 
 discharge is narrowed into a sort of stream, causing 
 a rapid escape of the electricity under such an at 
 tenuated form, as to produce a comparatively tran 
 quil and gradual discharge (p. 19). It is, as observed 
 by Faraday, when treating of this curious action of 
 pointed conductors, at the extremity of a point, that 
 the intensity necessary to charge the air is first ac 
 quired; from thence the particles recede. At the 
 same time, the point, having become the origin of 
 an active mechanical force, does, by the very act of 
 causing that force, namely, by discharge, prevent 
 any other part of the conducting body from which 
 it projects, from acquiring the same condition, and 
 thus preserves its own predominance. In this way 
 
 * Phil. Trans, for 1834, p. 221. 
 
ARTIFICIAL DISRUPTIVE DISCHARGES. 47 
 
 pointed conductors operate in discharging large ac 
 cumulations at considerable distances, under the 
 form of stream, brush, or glow, and so parry the 
 violent concentrated explosion commonly attendant 
 on them. This result ensues whether the pointed 
 conductor be affixed to the charged body or not 
 the opposite electrical state being always produced 
 in every case of discharge. Thus, if we present a 
 pointed metallic body to the conductor of the 
 machine, in the act of throwing off dense and 
 brilliant sparks, such sparks can no longer be 
 obtained (p. 11) the electric matter being silently 
 drawn off by the point. 
 
 f Brush discharge exhibits a great variety of 
 character in different media, its color, form, and 
 sound, being all greatly modified, according as it 
 takes place on a positive or negative surface. Ni 
 trogen gas, which enters in the proportion of four- 
 fifths into the composition of the atmosphere, has 
 the greatest power of originating this kind of 
 discharge. The brushes in this gas, are always 
 fine in form, light, and color ; and in nitrogen 
 rarefied by the air-pump the effects are still more 
 striking. 
 
 Brash discharge in air from a positive point 
 (p. 15) is frequently diffuse and spreading, pro 
 ducing the appearance called by sailors comazants, 
 or St. Helmo s fires ; from a negative point (p. 15) 
 it has often the character of a luminous star, exhibit 
 ing the appearances mentioned by Pliny and other 
 ancient writers (p; 21). 
 
48 ARTIFICIAL DISRUPTIVE DISCHARGES. 
 
 When the air in contact with a metallic con 
 ductor is rapidly charging, the end of the conductor 
 will often become covered with a glow of lambent 
 light, producing a peculiarly beautiful appearance; 
 this is greatly increased either by decreasing the at 
 mospheric pressure, or by augmenting the electrical 
 force. Faraday produced on a brass ball within an 
 exhausted receiver, a glow of light over an area of 
 two inches. The glow came over the ball, and 
 gradually increased in brightness until it was at last 
 very luminous, and stood up like a low flame of 
 half an inch or more in length,* being analogous 
 to one of the natural phenomena already mentioned 
 (p. 21). 
 
 "When the discharge is assisted by traces of con 
 ducting matter, it will traverse very considerable 
 distances. Thus a trace of sulphuric aoid, or small 
 particles of charcoal, or metallic dust, dispersed over 
 a strip of glass, will enable a battery to produce a 
 brilliant and intensely luminous discharge, over a 
 considerable distance. A trace of smoke will in like 
 manner facilitate the progress of the explosion. 
 When the intermediate air is highly rarefied in a 
 tube of glass, a jar may be discharged through it to 
 the extent of several feet, sometimes in one dense 
 mass, in others producing bifurcations and various 
 colored streams. 
 
 In the vacuum of a well-boiled barometer, the 
 electrical light is frequently of a beautiful green 
 
 * Experimental Researches, p. 47. 
 
FURTHER OBSERVATIONS ON THUNDER CLOUDS. 49 
 
 color, and in media of different kinds varying in 
 density, the color of the spark is altogether changed. 
 Thus in carbonic acid gas it is white and vivid, in 
 hydrogen gas it is red and faint. All this again be 
 comes modified by the quantity of electricity, and 
 by the kind and form of the conductors from which 
 it takes place. Considering, therefore, all these 
 circumstances, it is not at all surprising that we 
 find lightning assuming so great a variety of ap 
 pearance. 
 
 Further Observations on Thunder Clouds. 
 
 Although the disruptive discharge of thunder 
 storms, commonly proceeds at once through the air 
 intermediate between the charged clouds and the 
 earth, yet other more complicated discharges have 
 been supposed to occur, in consequence of electrical 
 disturbances between distinct and distant portions of 
 the atmosphere, in which the surface of the earth 
 becomes involved as a line of discharge between 
 them. The Italian philosopher, Beccaria, entertained 
 opinions of this kind ; he seemed to consider it im 
 possible that any cloud or collection of clouds, should 
 contain the great quantity of electricity observed in 
 thunderstorms, so as either to discharge or receive 
 it. He states that,, during the progress of a storm, 
 although the lightning frequently struck the earth, 
 yet the clouds were the next moment ready to make 
 a still greater discharge; and hence he concludes 
 that "the electrical matter is continually darting 
 from the clouds in one place, at the same time that 
 3 
 
50 FURTHER OBSERVATIONS 
 
 it is discharged from the earth in another." The 
 knowledge, however, we now possess, of the nature 
 and extent of electrical action, renders it quite un 
 necessary to resort to such hypothetical views, in 
 order to explain this phenomenon. The immense 
 absorption and evolution of electricity attendant on 
 chemical and other changes in common matter, is 
 quite sufficient to account for the apparently great 
 quantity of electricity active in thunderstorms. 
 Faraday has shown by strong experimental evi 
 dence, that the quantity of electricity holding the 
 elements of a single grain of water in chemical com 
 bination, is equal to that discharged in an ordinary 
 flash of lightning, and would, if discharged under 
 the form of a, current through a wire of platinum 
 about T T of an inch in diameter, keep it red-hot 
 in the air, for nearly four minutes.* The simple 
 view, therefore, which we have taken of the electri 
 cal conditions of a thunderstorm, is in no way em 
 barrassed by any difficulty arising out of the great 
 quantity of electricity liable to be discharged. Be 
 sides, it is not clear that the quantity is so great in 
 relation to conducting bodies, as might at first be 
 supposed. It is to be recollected, that we often 
 judge of the quantity of electricity present, by very 
 deceptive effects, as by the light of the spark, the 
 noise and expansive force of the discharge, and by 
 the damage done to imperfect conducting matter. 
 Now, we have seen (p. 31) that comparatively small 
 
 * Experimental Researches in Electricity, p. 250. 
 
ON THUNDERSTORMS. 51 
 
 quantities of electricity will produce intense effects 
 of this kind ; and it is doubtful whether any quan 
 tity of electricity ever discharged in a single flash 
 of lightning has been sufficient to melt a copper 
 rod a foot in length and three-fourths of an inch in 
 diameter. 
 
 The general condition of a thunderstorm is, as 
 already observed, (p. 5), the charging and discharg 
 ing of a stratum of air intermediate between the 
 masses of cloud and the earth, or otherwise interme 
 diate between two masses of clouds in opposite 
 electric states; the source of the charge being the 
 evolution of electricity in consequence of certain 
 physical changes in the state and condition of the 
 atmosphere. Discharges of lightning produced by 
 this state of things, may arise during the formation 
 or presence of clouds in a given place, or during 
 their formation and motion through the air, by 
 which a large stratum of polarized particles is swept 
 along over the earth s surface ; or they may arise 
 from the motion of an upper current of cloud over 
 a large track of atmosphere, which has from any 
 previous train of circumstances, become polarized ; 
 or otherwise, from the operation of successive super 
 imposed strata of air and clouds, reaching to the 
 surface of the earth ; or otherwise, from the opera 
 tion of distant and distinct portions of the atmo 
 sphere, oppositely charged, and which may hence 
 discharge into each other, under a great variety of 
 conditions. 
 
52 EEECTRICAL DISCHARGES. 
 
 Electrical Discharges. 
 
 Thunderstorms arising out of a rapid formation 
 of vapor, and in a limited portion of the air, as 
 illustrated in fig. 1, (p. 13,) have been well described 
 by Beccaria. " The first appearance of a thunder 
 storm," he says, " generally happens when there is 
 little or no wind ; there is one dense cloud or more, 
 increasing very fast in size, and rising into the 
 higher regions of the air. The lower surface is 
 black, and nearly level, but the upper is finely 
 arched, and well-defined. Many of these clouds 
 seem piled one over another, all arched in the same 
 way, but they keep continually uniting, swelling, 
 and extending their arches. At the time of the 
 rising of this cloud, the atmosphere is generally full 
 of a great number of separate clouds of whimsical 
 and irregular shapes, and apparently motionless. 
 All these upon the appearance of the thunder cloud 
 draw towards it, become more uniform in their 
 shape, and at length form with it one common mass. 
 Sometimes the thunder cloud will swell very fast 
 without the conjunction of such clouds, and when 
 it is grown to a great size, its lower surface is fre 
 quently ragged, and swells into large protuberances 
 which bend uniformly toward the earth ; some 
 times one whole side of the cloud has an inclination 
 toward the earth. When the eye is under the 
 thunder cloud, it is at last seen to darken fearfully, 
 and a number of small clouds, the origin of which is 
 never detected, drive about it in uncertain direc- 
 
ELECTRICAL DISCHARGES. 53 
 
 tions. Rain and hail about this time fall in abun 
 dance. During the swelling and extension of the 
 cloud over a large tract of country, lightning darts 
 through its mass, and at length strikes toward the 
 earth in opposite places ; the longer the lightning 
 continues, the rarer the cloud becomes, till at length 
 it breaks up in different places, and shows a clear 
 sky."* 
 
 Captain Ward, R. N"., gives the following inter 
 esting account of the phenomena observed by him 
 during a thunderstorm in the Bay of Honduras in 
 the West Indies, whilst he was in command of his 
 Majesty s ship Pelican, in the autumn of the year 
 1806. " The night was nearly calm, and the heat 
 oppressive; heavy black clouds intensely charged 
 with the electric fluid, overspread the earth, and 
 about midnight, after a little whirl of wind, began 
 to approach it. A discharge of lightning of the 
 most splendid, and at the same time most awful 
 character, speedily ensued. The electric fluid seemed 
 to pour down upon the earth and sea in repeated 
 streams, occasionally illuminating every thing about 
 us with a brilliancy surpassing noon-day, but leaving 
 us at the next instant in pitchy darkness. This 
 fearful display, attended by roaring peals of thunder, 
 lasted about an hour, during which one of the dis 
 charges fell on our main-royal mast-head, shivered 
 it, together with the top-gallant mast and topmast 
 in atoms, scattering the fragments to an immense 
 
 * Letter e deW Elettrismo, p. 151 to 167. 
 
54 ELECTRICAL DISCHARGES. 
 
 distance, so that not a piece of any size could be 
 found. The discharge continued its course with 
 damage along the mainmast in an irregular spiral 
 form down to the very heel and step of the mast, 
 where it disappeared." 
 
 One of the most awful accounts, however, of a 
 thunderstorm at sea is that given by an intelligent 
 observer, present as a passenger in the splendid 
 American packet-ship New- York, which was struck 
 and damaged by lightning in the Gulf-stream, 
 April 19th, 1827, in her passage from New- York to 
 Liverpool. "About half-past five in the morning, 
 being in our berths, we were roused by a sound like 
 the report of heavy cannon close to our ears. In a 
 moment we were all out. From the deck the 
 word was quickly passed that the ship had been 
 struck by lightning, and was on fire. Every one 
 ran on deck ; there, all the elements were in violent 
 commotion : it had been broad day, but so dark, so 
 dense, and so close upon us were the clouds, that 
 they produced almost the obscurity of night. There 
 was just sufficient light to give a bold relief to every 
 object in the appalling scene ; the rain poured down 
 in torrents, mingled with hailstones as large as fil 
 berts ; these lay upon the deck nearly an inch 
 thick ; overhead blazed the lightning on all sides, 
 accompanied by simultaneous reports ; the sea ran 
 mountains high, and the ship was tossed rapidly 
 from one sea to another. One appearance was pe 
 culiarly remarkable : the temperature of the water 
 was 74 of Fahrenheit, whilst that of the atmosphere 
 
ELECTRICAL DISCHARGES. 56 
 
 was only 48. This caused, by evaporation and con 
 densation, immense clouds of vapor, which, ascend 
 ing in columns all around us, exhibited the appear 
 ance of innumerable pillars supporting a massive 
 canopy of clouds. In all directions might be seen 
 water-spouts, which rising fearfully to the clouds, 
 seemed actually to present to the eye a combination 
 of all the elements for the destruction of every thing 
 on the face of the deep." These accounts afford 
 highly instructive examples of the spontaneous evo 
 lution of electricity in the atmosphere, giving rise to 
 a vast electrical disturbance, and subsequent disrup 
 tive discharges (p. 15). 
 
 The altitude of the masses of cloud, forming the 
 upper terminating plane of the electrified system, 
 does not appear to be so considerable as their hori 
 zontal dimensions, which not unfrequently extend 
 over a large tract of country, producing almost 
 simultaneous discharges in various places. Admiral 
 Eoss states, that the storm which shivered the masts 
 of the Desiree in Port Antonio, Jamaica, in the 
 autumn of 1803, was witnessed by an observer some 
 short distance up the adjacent hill. It appeared to 
 take place close under him, during a fine clear, star 
 light evening overhead. 
 
 On the night of the 14th of April, 1718, a thun 
 derstorm occupied the coast of Brittany between 
 Landerneau and St. Pol de Leon, and damaged no 
 less than twenty-four church towers.* In 1774 a 
 
 * Annuaire pour 1838, p. 479. 
 3* 
 
56 ELECTRICAL DISCHARGES. 
 
 severe thunderstorm spread itself over London. The 
 lightning damaged St. Peter s church considerably, 
 and at the same time several other discharges occur 
 red in various places far distant from each other. A 
 Dutch ship in the river off the Tower was struck, also 
 the obelisk in St. George s fields, Southwark, together 
 with a chimney at Lambeth, and a house at Vauxhall.* 
 On the llth January, 1815, another thunderstorm 
 occupied no less a space than that contained between 
 the North Sea and the Rhenish provinces, and severe 
 ly damaged twelve church towers in various parts of 
 this extensive tract, f 
 
 The electrical disturbance is sometimes so very 
 rapidly progressive, that repeated discharges are ob 
 served to occur in the same place, in quick succession. 
 The church and buildings of the abbey of Notre 
 Dame, in the town of Ham, in France, was, during 
 the night of the 25th April, 1760, struck three times 
 in the short interval of twenty minutes, and the 
 whole burnt to the ground.:): His Majesty s ship 
 Hyacinth had first her fore-topmast, then her main- 
 topmast rent in pieces by two discharges which 
 followed close upon each other. 
 
 His Majesty s ship Madagascar, in coming to an 
 anchor in the Corfu Channel, in January, 1829, was 
 struck by lightning no less than five times within 
 two hours ; the sails were set on fire, and other 
 
 * Phil Trans., vol. Ixiv. for 1774. 
 
 f Annuaire pour 1838, p. 481. 
 
 \ Idem, p. 482. 
 
 Report of Commission, p. 75. 
 
ELECTRICAL DISCHARGES. 57 
 
 damage done. His Majesty s ship ^Etna was in the 
 same storm, and not far distant ; she experienced re 
 peated discharges : "the descent of the electric fluid 
 was frequent and at very short intervals." * 
 
 His Majesty s frigate Glorinde was struck and 
 damaged by lightning, on the coast of Ceylon, in the 
 spring of the year 1813. The following is a very 
 clear and circumstantial account of the phenomena, 
 by Captain Briggs, E. N., who commanded the ship. 
 "The weather was moderate. About three in the 
 afternoon we observed a dark cloud approaching the 
 ship from the windward quarter : this induced me to 
 clew up the topsails. About an hour afterwards, the 
 ship was struck by lightning : the cloud we had ob 
 served, was charged with electricity, and had burst 
 on the ship. The mainmast was shivered in pieces ; 
 only a wreck remained. Three men were killed, 
 and many hurt." 
 
 Now it is clear, that in this instance, the dis 
 ruptive discharge was caused by the progressive 
 motion of a charged cloud, driven by an upper 
 current, upon a comparatively tranquil air, but pos 
 sibly in a polarized state, sweeping along with it a 
 portion of charged atmosphere, and accumulating 
 forces, sufficient to make it approach the earth, 
 within a distance at which the forces could neutralize 
 through the intermediate stratum. 
 
 The following is a similar instance, related by 
 Captain Haydon, K. N., in which the whole atmo 
 sphere and cloud travelled together in the direction 
 
 * Report of Commission, p. 87. 
 3* 
 
58 ELECTRICAL DISCHARGES. 
 
 of the wind. " His Majesty s ship Cambrian, off Ply 
 mouth, February 22, 1799, strong gales and squally ; 
 observed a tremendous squall coming down upon us ; 
 turned the hands up to clew up the close-reefed top 
 sails. Whilst they were so employed, a ball of fire 
 struck the topmast-head, killed two men and wounded 
 many others. The number taken below amounted 
 to about twenty." 
 
 The case of His Majesty s ship Topaze, struck by 
 lightning in the West Indies, in July, 1802, is another 
 remarkable instance of this source of disruptive dis 
 charge. Captain H. Edwards, E. N"., who was in the 
 ship at the time, says, "When off the west end of 
 St. Domingo, about two or three leagues from the 
 shore, we were becalmed. About midnight a light 
 breeze came off the land, bearing a dark isolated 
 cloud; the cloud began to discharge its lightning 
 within an apparently short distance of the ship, and 
 after five or six vividly forked flashes, struck our 
 mizzen royal-mast, and passed down the mizzen- 
 rnast, shivering and rending the spars in its course." 
 
 It appears that the light breeze from the shore 
 enabled them to get the ship s head the right way, 
 so as to lay her with her stern to the shore : hence 
 the mizzen-mast was the mast first acted on by the 
 cloud. 
 
 A great variety of instances might be quoted, in 
 confirmation of disruptive discharges being produced 
 on the principles already explained (p. 12) : they all 
 differ from the state of things observable in more 
 stationary thunderstorms (p. 52) in this, that whilst 
 
ASCENDING STROKE. 59 
 
 in such thunderstorms, there is often a rapid, and 
 continuous series of discharges produced by the 
 spontaneous evolution of electricity in one place: 
 we trace in the progress of highly electrified clouds, 
 deliberate discharges of a passing kind, few in num 
 ber, in some instances not extending beyond one or 
 two at the furthest. 
 
 Electrical disturbances, involving similar condi 
 tions, but of a more complicated character, sometimes 
 proceed with continued destructive effects over a 
 long tract of country, the atmosphere appearing to 
 assume, during the progress of the masses of electri 
 fied cloud, an intensely charged state. Such storms 
 have been observed to pass from the southern shores 
 of England to the north of Scotland and Ireland. 
 A thunderstorm of this kind occurred in July, 1827. 
 It began on the south-west coast of Devonshire on 
 Sunday evening, reached Cheltenham the same night, 
 and Glasgow the next morning, the atmosphere 
 throughout this extent appearing to undergo a rapid 
 and progressive change.* 
 
 Ascending Stroke. 
 
 Sometimes the thunderbolt passes from the earth 
 to the clouds, and in this case it is called by some 
 philosophers the " ascending stroke," by others " the 
 returning stroke." Facts are not wanting to indicate 
 the progress of electricity upward. The Marquis 
 Maffei was the first who observed this curious phe- 
 
 * Provincial and London Journals. 
 
60 ASCENDING STROKE. 
 
 nomenon. He distinctly saw, during a storm, the 
 lightning issue from the ground with a loud noise. 
 The Abbe Lioni and M. Segnier of Nismes, saw the 
 lightning rise in the form of flame six feet high, 
 followed by a loud noise. 
 
 One of the most interesting cases of the ascend 
 ing stroke has been recorded by John Williams, Esq. 
 It took place upon the hills above the village of Great 
 Malvern, on the 1st July, 1826. A party had taken 
 refuge from the storm in a circular building roofed 
 with sheet iron, and one of the ladies on entering 
 the hut expressed her alarm lest the lightning should 
 be attracted by the iron roof. They had scarcely 
 entered their retreat, and were about to partake of 
 some refreshment, when a violent storm of thunder 
 and lightning came on from the west. About forty- 
 five minutes past two, a gentleman who stood at the 
 eastern entrance, saw a ball of fire which seemed to 
 him moving on the surface of the ground. It in 
 stantly entered the hut, forcing him several paces 
 forward from the doorway. On his recovering from 
 the shock, he found his sisters on the floor of the hut, 
 fainting, as he imagined, from terror. Two of the 
 ladies had died instantly ; another lady, and the rest 
 of the party, were much injured. The explosion 
 which followed the flash of lightning, was said, by 
 the inhabitants of the village, to have been terrific. 
 Mr. Williams, who immediately examined the hut, 
 found a large crack in the west side of the building, 
 which passed upward from near the ground to the 
 frame of a small window, above which the iron roof 
 
ASCENDING STROKE. 61 
 
 was a little indented. Mr. Williams conceived it to 
 be quite clear, from the place of the fragments of 
 stone and other appearances, that the clouds were 
 negatively electrified during this storm.* 
 
 A very curious instance of the ascending stroke 
 is related by G. F. Eichter, in his work on thunder. 
 He informs us that in the cellar belonging to the 
 Benedictine monks of Fontigno, while the servants 
 were employed in pouring into a cask some wine 
 which had been just boiled, a fine light flame ap 
 peared round the funnel, and they had scarcely finished 
 their operations, when a noise like thunder was heard ; 
 the cellar was instantly filled with fire ; the cask was 
 burst open, although hooped with iron, the staves 
 were thrown with prodigious violence against the 
 wall, and, on examination, a hole of three inches di 
 ameter was found in the bottom of the cask.f 
 
 On the 24th of February, 1774, lightning struck 
 the steeple of the village of Eouvroi, to the north 
 west of Arras. A pavement composed of large blue 
 stones, which was laid under the steeple was violently 
 raised upward. 
 
 In the summer of 1787 lightning struck two per 
 sons who had taken refuge under a tree near the 
 village of Tacon, in Beaujalois. Their hair was 
 driven upward and found upon the top of the tree. A 
 ring of iron which was upon the shoe of one of these 
 persons was found afterwards suspended on one of the 
 upper branches. 
 
 * Encyclopaedia Britannia, vol. 8, p. 619. 
 f London JZncyclopcedica, vol. 8, p. 59. 
 
62 ASCENDING STROKE. 
 
 On the 29th of August, 1808, lightning struck a 
 small building near the hospital of Salpe triere in 
 Paris. A laborer who was in it was killed, and after 
 the event the pieces of his hat were found incrusted 
 on the ceiling of the room. 
 
 When trees have been barked by lightning, it 
 frequently happens that the bark is stripped from the 
 base upward to a certain height, and the upper part 
 of the tree is untouched. This occurred with several 
 trees in the Champs Elysees, at Paris, in a storm which 
 took place in June, 1778. 
 
 The leaves of trees which have been struck by 
 lightning often exhibit the effects of heat on their 
 lower surfaces, but not at all on their superior sur 
 faces. 
 
 Among the numerous manifestations of the dis 
 charge of electric matter from the surface of the earth, 
 one of the most circumstantial and authentic is due 
 to Brydone, who, being on the spot where the oc 
 currences took place, was in part witness to them, and 
 collected the particulars from other eye-witnesses 
 with scrupulous care. 
 
 On the 10th July 1785, a storm broke out be 
 tween noon and one o clock, in the neighborhood of 
 Coldstream. During its continuance, there occurred 
 in the surrounding country several remarkable acci 
 dents. 
 
 A woman who was cutting grass on the banks of 
 the Tweed, was suddenly thrown down without any 
 apparent cause. She called her companions immedi 
 ately to her aid, and told them that she received a 
 
ASCENDING STROKE. 63 
 
 sudden and violent blow on the soles of her feet, but 
 whence it proceeded she could not tell. At the mo 
 ment this happened there was neither thunder nor 
 lightning. 
 
 A shepherd attached to a farm called Lennel 
 Hill, saw a sheep suddenly fall, which the moment 
 before appeared in perfect health. He ran to raise 
 it from the ground, and found it stiff dead. The 
 storm was then approaching, but distant. 
 
 Two coal-wagons, driven by two boys, seated on 
 the benches in front of them, had just crossed the 
 Tweed, and were in the act of ascending a hill on the 
 banks of the river, when a loud explosion was heard 
 like the report of several guns fired nearly together, 
 and unattended by any rolling or continued sound 
 like that which usually accompanies thunder. At 
 the moment of this explosion the boy who drove the 
 second wagon saw the foremost wagon with the two 
 horses and driver suddenly fall to the ground, the 
 coal being scattered about in all directions. On ex 
 amination, the driver and horses were found to be 
 stiff dead. The coal which was dispersed, had the 
 appearance of having been for some time in the fire. 
 At the points where the tires of the wheels rested at 
 the time of the explosion, the ground was found to 
 be pierced by two circular holes, which being exam 
 ined by Brydone half an hour after the occurrence, 
 emitted a strong odor resembling that of ether. The 
 tires of the wheels showed evident marks of fusion 
 at the points which were in contact with the road at 
 the moment of the explosion, and at no other part. 
 
64 ASCENDING STROKE. 
 
 The hair was singed on the legs and under the bel 
 lies of the horses, and by a careful examination of 
 the marks left in the dust of the road where they 
 fell, it was apparent that they must have been struck 
 suddenly stone dead, so that no life remained when 
 they touched the ground. Had there been any con 
 vulsive struggle, the marks would have been visible. 
 The body of the driver was scorched in different pla 
 ces, and his dress, shirt, and particularly his hat, 
 were reduced to rags. A strong odor proceeded 
 from them. 
 
 All the witnesses of this occurrence agreed, that 
 no luminous appearance whatever attended it. The 
 driver of the second wagon was conversing with his 
 comrade, and was looking toward him at the mo 
 ment he was struck down, being at about twenty 
 yards behind him, but saw no light. A shepherd 
 standing in an adjacent field, told Mr. Brydone that 
 he had his eye on the wagon at the very instant of 
 the explosion, but he saw no light. He saw a vortex 
 of dust arise at the place of the explosion, but unac 
 companied by any luminous appearance. Finally, 
 Mr. Brydone himself at the moment of the event was 
 standing at an open window, with a watch in his 
 hand, explaining to the persons around him the 
 method of calculating the distance of the lightning 
 by observing the interval between the flash and the 
 thunder, and he heard the explosion, but perceived 
 no light.* 
 
 Professor Dewey, D. D., of Rochester University, 
 
 * Dr. Lardner s Lectures on Science and Art, Vol. II., p. 72. 
 
ASCENDING STROKE. 65 
 
 related to the writer some few months since, that 
 during his connection with Williamstown College, 
 Mass., a church in South Williamstown was struck 
 by lightning. The house was carefully examined 
 loj himself after it was struck, when he saw leaves 
 of flowers that had grown by the walls of the 
 church, lodged in the cobwebs up under the eaves. 
 
 Some time last summer Mr. Platt s house, Deep 
 Kiver, Connecticut, was struck by lightning. After 
 the accident, the house was carefully examined by 
 myself and many others. It was evidently an in 
 stance of the " ascending stroke." The front part of 
 the house, including the entire length of the wing 
 attached, was traversed by the lightning, leaving 
 marks of terrific violence wholly unaccountable, un 
 less done by an upward force. 
 
 We have multiplied the number of instances un 
 der this head, for two reasons : First, because so 
 many of those little read in electrical science utterly 
 disbelieve the existence of an upward stroke, and 
 even laugh at the idea as absurd and whimsical. 
 Secondly, because an intelligent belief in an upward 
 stroke has an important relation to the application 
 of lightning conductors for the protection of build 
 ings, as we shall presently see. 
 
 Various electrical phenomena, of a very interest 
 ing kind, have been observed by travellers, when 
 ascending lofty mountains. In 1767, M. M. Saus- 
 sure, Pictet, and Jallabert, when on the top of Mount 
 Breven, received small electric shocks at their finger- 
 ends, by stretching out their arms, and a whistling 
 
66 ASCENDING STROKE. 
 
 noise even accompanied them. The gold button on 
 M. Saussure s hat yielded distinct sparks. In 1814, 
 a party of Englishmen experienced similar effects on 
 Mount ^Etna, during a storm of thunder and light 
 ning, accompanied by a fall of snow. One of the 
 party felt his hair moving, and upon raising his 
 hand to his head, a buzzing sound issued from his 
 fingers. The rest of the party experienced the same 
 sensations, and by moving their hands and fingers 
 they produced a variety of musical sounds, audible 
 at the distance of forty feet. On the 27th of June, 
 1825, Dr. Hooker and a party of botanists witnessed 
 effects like those described, during a fall of snow on 
 Ben-Nevis, when there was no thunderstorm. The 
 snow fell very heavily for nearly two hours. Soon 
 after it began, a hissing sound was heard every 
 where around them, and continued about an hour 
 and a half. It seemed to proceed from every point 
 in the vicinity; and on arriving at the cairn on the 
 summit of the mountain, they could almost determine 
 the stones from which the electricity issued. The 
 hair of several of the party exhibited, when touched, 
 the usual electrical phenomena.* 
 
 * Encyclopaedia Britannica, vol. viii. p. 620. 
 
SECTION II. 
 
 APPLICATION OF METALLIC CONDUCTORS TO 
 THE DEFENCE OF BUILDINGS AND SHIP 
 PING FROM LIGHTNING. 
 
 Laws of Disruptive Discharges Observed effects on Buildings and 
 Shipping Practical results of the preceding Inquiries Na 
 ture and operation of Lightning Rods Laws of Electrical Con 
 duction Mechanical effects of the Disruptive Discharge What 
 quantity of Metal is requisite in the construction of a Lightning 
 Rod How far does its protecting power extend. 
 
SECTION II. 
 
 Laws and Operation of Disruptive Discharge. 
 
 WHATEVER may be the theoretical views entertained 
 relative to the immediate source of lightning, and the 
 manner in which disruptive electrical discharges oc 
 cur in nature, it will be well to bear in mind, that all 
 such discharges, have nevertheless one common char 
 acter, all produce similar effects, and are all gov 
 erned by the same laws. We propose, therefore, to 
 consider these laws more particularly, with a view 
 of arriving at certain practical deductions, immedi 
 ately bearing on the question of the defence of build 
 ings and shipping from lightning. 
 
 If we attentively examine the many recorded in 
 stances in which buildings and ships have been dam 
 aged by lightning, the course of the discharge may 
 generally be traced ; and this course is invariably 
 determined through a given line or lines which, upon 
 the whole, oppose the least resistance to the neutrali 
 zation of the electrical forces. Both space and time 
 are, as it were, economized in the restoration of the 
 
70 LAWS AND OPERATION OF 
 
 electrical equilibrium (pp. 4, 5); for however small we 
 assume the duration of the discharge to be, or how 
 ever limited the distance through which it strikes, 
 both these quantities would become still less, were 
 other lines of transit provided of still less resistance. 
 This is the leading phenomenon of all disruptive dis 
 charges ; hence lightning seizes upon such bodies as 
 lie convenient and ready for its purpose, absolutely 
 avoiding other bodies, however near, from which it 
 can receive no assistance. And it may be further 
 observed, as a most wonderful and interesting fact, 
 that at the instant before the explosion takes place, 
 the stream of electricity, in the act of moving to re 
 store the equilibrium of distribution, feels its way as 
 it were in advance, and absolutely marks out the 
 course it is about to take, an inductive action being 
 impressed upon such bodies as happen to lie in the 
 line or lines of least resistance ; this previous induc 
 tion, by a sort of foresight, determines the course of 
 the discharge. Its progress therefore is not, as many 
 imagine, left to the chances of the instant, to be, as 
 it were, attracted or drawn aside by metallic bodies 
 at any given point ; on the contrary, the whole course 
 of a stroke of lightning is already fixed and settled, 
 before the discharge takes place. 
 
 The evidence deducible from observation as well 
 as from physical investigation, is most conclusive on 
 this point. It is quite clear, from what has been 
 already shown (p. 15), that any artificial elevation 
 on the earth s surface is, in respect of a thunderstorm, 
 a mere point in one of the terminating planes of a 
 
DISRUPTIVE DISCHARGE. 
 
 71 
 
 great electrical disturbance: The electrical forces 
 cannot therefore be supposed to operate exclusively 
 between such an elevation and a charged cloud. A 
 building or ship, is struck by lightning only in con 
 sequence of its being a point in one of the electrified 
 surfaces ; in short, a heterogeneous mass, acciden 
 tally placed in a position to facilitate the neutraliza 
 tion of the electrical forces in a given direction, ex 
 tending, perhaps, over many square miles of cloud 
 and opposed sea or land (p. 55). 
 
 By way of illustration, let P N (fig. 10) represent 
 the opposed terminating surfaces of the clouds and 
 sea at the time of a thunderstorm, and N the position 
 of a ship at the instant of discharge ; let a b be the 
 point, in which from any determining cause, the par 
 ticles of the intervening air give way. Imagine fur 
 ther, that there were presented for the course of the 
 
72 LAWS AND OPERATION OF 
 
 discharge, such lines of transit, as a b c d, a b e N, a b/N, 
 a b g N ; then the question, whether the ship N would 
 be struck by lightning, would depend on the respec 
 tive resistances, in the direction of these lines ; it 
 might so happen, that the resistance in the direction 
 a b c c?, although very near the vessel, might, from a 
 variety of causes, be so much less than in any one of 
 the other lines, that the discharge would not touch 
 the ship at all. Conversely, the resistance might 
 be greater in the direction abed than in any other, 
 in which case the discharge would become deter 
 mined through the ship, and one, two, or three, of 
 the masts, would be struck by a division of the spark, 
 in the way already stated (pp. 35, 36), according to the 
 equality or difference of the resistance in these di 
 rections. 
 
 We must not, however, proceed too hastily with 
 out verifying principles by an appeal to experience : 
 for however perfect theoretical views of such ques 
 tions may be, it is still always desirable to adhere 
 carefully to facts. 
 
 Her Majesty s cutter HaivJc, was struck by light 
 ning in Broadhaven Koads on the 21st of January, 
 1840, and seriously damaged. About the same time, 
 the electrical discharge fell so near the Neptune, a 
 small revenue cruiser at anchor in Ely Bay, as to 
 cause the vessel to fairly reel by the concussion.* 
 Her Majesty s ship Southampton, of fifty guns, ex 
 perienced a heavy storm of lightning and thunder 
 on the 30th of June, 1842, on the coast of South 
 
 * Mayo Constitution. 
 
DISRUPTIVE DISCHARGE. 73 
 
 America, when a heavy electrical discharge fell so 
 close to the ship, that it appeared to strike the main- 
 chains.^ 
 
 During the passage of Her Majesty s ship Van 
 guard, of eighty guns, from Portsmouth to the Med 
 iterranean, in 1840, a dense explosion of lightning 
 fell close upon the ship s quarter, without affecting 
 the masts, f 
 
 The Dart steam-packet, whilst on her passage 
 from London to Margate, in July, 1829, was exposed 
 to a severe thunderstorm about five miles below the 
 Nore. The electrical discharge struck the sea so 
 near the vessel as to shake her considerably. One 
 of the passengers stated that he saw a ball of fire fall 
 into the water about twenty feet from the larboard 
 side of the ship.;); 
 
 A great number of instances of this kind might 
 be adduced in support of this important fact ; it is 
 however unnecessary to go at present into any fur 
 ther detail. We will therefore pass on to the track 
 of the discharge, supposing it to be determined in 
 the direction of the masts; and with a view of sim 
 plifying the question, we will select a common case 
 in which it falls on one mast only, viz., on the main 
 mast, in the direction a 1} fN (fig. 10). In pursuing 
 this course, the same general principle is apparent, 
 i. e., the electrical discharge is observed to fall on all 
 those bodies which tend to assist its progress, and 
 which happen to occupy certain relative positions, 
 
 * Master s log. | Extract from private letter. 
 
 \ Report of Commission on Shipwreck by Lightning, p. 84. 
 4 
 
74 OBSERVED EFFECTS ON 
 
 and upon no others : attacking with destructive vio 
 lence, imperfect conducting matter, and producing in 
 various insulators, intermediate between good con 
 ductors, all the effects of a powerful expansive force. 
 If we examine the course of any discharge of light 
 ning, through a building or a ship, we shall find this 
 effect invariable. The damage has always ensued 
 where good conductors cease to be continued, and 
 the destructive effects most apparent, are those com 
 monly caused by an expansive force. 
 
 Observed Effects on Buildings and Ships. 
 
 The damage done by lightning to Her Majesty s 
 ship Rodney, of ninety guns, may be adduced in 
 illustration of this result in nature. This vessel, 
 one of the finest of our line-of-battle ships in the 
 Mediterranean, was struck by lightning on the 6th 
 of December, 1838, off the south-east coast of Sicily, 
 at 9 A. M. The electrical discharge fell on the vane- 
 spindle, which was of wood, and on the truck at the 
 mast-head. It then glanced over the royal pole to 
 the head of the top-gallant mast, probably assisted 
 by the moisture on its surface (p. 48) ; here it fell on 
 a copper funnel, sixteen inches long and ten inches 
 in diameter, placed on the mast for the support of 
 the rigging. The resistance through the air, over 
 the surface of the mast, seems to have been greater 
 than through the wood ; hence the top-gallant mast 
 was shivered ; it now seized upon the metals about 
 
BUILDINGS AND SHIPS. 75 
 
 the head of the topmast, and also on some men 
 there on the cross-trees. From thence it struck 
 over the surface of the topmast to the metallic 
 bodies about the parrel of the topsail-yard, and so 
 passed per saltum to the lower mast, leaving it in a 
 tottering state. The expansive effect was so great, 
 that thirteen of the iron hoops were burst open : 
 about seven feet above the deck the concentrated 
 shock divided; one portion passed over the ham 
 mock nettings into the sea ; a second seized upon a 
 metallic pump used for washing decks, and passed 
 along the course of it through the ship s side, a third 
 division passed below to the orlop deck, and through 
 the metallic bodies in the hull, leaving the ship be 
 tween decks full of a sulphurous odor and an ap 
 parent smoke. In this course, the discharge evi 
 dently sought assistance from all the conducting 
 matter it could find, viz., wet ropes, copper funnel 
 for rigging, iron work, &c., about the topmast cap, 
 men on the cross- trees, metallic bodies about the 
 parrel of the topsail-yard, &c. ; and between all 
 these it produced destructive effects. The inter 
 rupted circuit is quite evident in this case. It is 
 traceable, first, to the copper funnel ; secondly, from 
 thence to the conducting bodies at the heel of the 
 top-gallant mast ; thirdly, from thence to the metallic 
 masses about the yard ; fourthly, between this and 
 the head of the lower mast ; fifthly, from this point 
 over the iron hoops on the lower mast; lastly, to 
 the hull and sea. The circumstance of the dis 
 charge striking over some portions of the mast with- 
 
76 
 
 out damage, is quite in accordance with all the 
 known laws of electrical action already described 
 (p. 48) ; thus a trace of water will allow a highly- 
 charged jar to explode over a slip of glass without 
 damage; and Dr. Franklin found he could not de 
 stroy a wet rat by artificial electricity, although he 
 could a dry one, in consequence of the moisture 
 conducting the charge over the surface of the body. 
 The following cases of damage by lightning, 
 which have recently occurred in London are worthy 
 of attentive consideration, inasmuch as the facts are 
 still present to us, and the evidence they furnish 
 of the course of electrical discharges is very com 
 plete. They have therefore been somewhat mi 
 nutely described. 
 
 St. Martin s Church, struck ly Lightning, 28th July, 
 1842. 
 
 Before tracing the course of the electrical dis 
 charge through the tower of this beautiful building, 
 it will be requisite briefly to notice the position of 
 the various rooms and substances through which it 
 passed, together with such other circumstances as 
 bear immediately on the great points under con 
 sideration. 
 
 A section of this tower is given in figs. 11 and 12. 
 The spire, s C A, terminates in an iron rod, c A, formed 
 into a spindle at its extreme point, for the support 
 of the vane, A. This rod is from four inches and a 
 half to five inches square, and about twenty-seven 
 
STRUCK BY LIGHTNING. 
 
 77 
 
 feet in length. It projects about twelve feet into 
 the air, and passes fifteen feet into the spire through 
 a gilded ball of copper, thirty-three inches in diame 
 ter, and one-sixteenth of an inch thick, and through 
 two solid blocks of stone. It is supported within by 
 a strong cross of iron, let into the masonry at c (fig. 
 11). The weight of the bar is about twelve cwt. 
 and three-quarters, and its extreme point about two 
 hundred feet from the ground. There are other 
 iron crosses in the interior of the spire, besides that 
 supporting the spindle of the vane, as at t and v (fig. 
 11) : these serve as cramps to the masonry ; they are 
 not connected with each other. The vane at A is 
 constructed of sheet copper, well gilded, and is 
 about eight feet long and six feet wide. 
 
 The spire is a light hollow structure, forty-four 
 feet high, standing on an open cupola, and sur 
 rounded by ornamental columns and arches. The 
 floor of this cupola is covered with lead, and there 
 is a massive framework of wood and iron, resting 
 on it. This frame is constructed in two parts, for 
 the support of a flagstaff F, one of which can be 
 pushed out clear of the tower when required. Be 
 neath the cupola is the dial-room / containing the 
 iron spindles of the clock faces, as at e fn. The 
 figures marking the hours constitute portions of the 
 stone-facing which surrounds the recesses of the 
 circles forming the centre of the dials: these 
 circles are formed of shutters of wood and iron, 
 in eight divisions, and are painted black, The 
 four cross rods ate /(fig. 12,) carry the hour and 
 
ST. MARTIN S CHURCH 
 
 FIG. 11. 
 
STRUCK BY LIGHTNING. 
 
 minute hands of each dial, and are supported in 
 the middle of the dial-room f, without touching 
 the walls. 
 
 Under the dial-room is the belfry B, in which are 
 the bells, suspended in frames in the usual way; 
 they weigh from five to thirty-one cwt. Beneath the 
 belfry is the clock-room G ; the clock in this room 
 is supported in a massive iron frame fixed to the 
 floor ; an iron rod / G, about three-fourths of an 
 inch in diameter, and forty-six feet long, passes from 
 the wheel-work up through the belfry B to the 
 spindles at/ by which the requisite motion is con 
 veyed to the hands on the dial- plates ; this rod is 
 constructed of several pieces, united by brass screws : 
 it is cased in wood, and passes within ten inches of 
 the lip of each bell. 
 
 Beneath the clock-room is the ringing-chamber 
 K, having windows w w with iron frames ; imme 
 diately without these is the lead, covering the roof 
 of the church, as at M. 
 
 "We have now before us almost every particular 
 requisite to a clear comprehension of the track, and 
 phenomena of the electrical explosion which fell on 
 this fine structure. 
 
 The first point struck was the point of the vane- 
 spindle at A; the discharge passed into the spire 
 through the rod Ac, without any damage to the 
 blocks of stone immediately surrounding it, and 
 without affecting the copper ball or the gilding of 
 the vane. The only effect produced was the dis 
 turbance of a little cement about the ball, which 
 
80 
 
 seemed as if shaken by a violent concussion of the 
 air. At the cross c the discharge left the vane-rod, 
 and passed into the masonry of the spire, starting 
 an angle stone, and from t thence so damaged the 
 spire in passing down it, as to leave the whole in a 
 tottering state. Two blocks of stone were thrown 
 completely out of their places, and fell through the 
 roof into the church, the joints of the spire were 
 all loosened, and its general surface contorted. Two 
 other stones were quite dislocated ; if these had also 
 been thrown out, the whole of the upper portion of 
 the spire must have fallen. From the base of the 
 spire, the discharge fell with destructive violence 
 upon the frame-work of the flagstaff at c?, the wood 
 work of which was shivered, and then seizing the 
 lead floor of the cupola, it forced a passage to a 
 metal clamp within the masonry, where it tore up 
 and fractured a large flat stone, and turned it com 
 pletely over ; in this way it passed to the nearest 
 points outside the tower leading to the north and 
 west dials: upon these the discharge divided, and 
 fell upon the gilded letters xi. and xn., the gold of 
 which, on the west dial more especially, was burnt 
 up and blackened. From these points it exploded 
 upon the minute-hands ; here it also blackened the 
 gold, and damaged the points of the hands. From 
 this, it passed along the spindles of the north and 
 west dials into the dial-room, without affecting the 
 surrounding parts, and seizing the iron rod/G, con 
 necting the spindles with the clock, it passed safely 
 within its case of wood, and between the masses of 
 
STRUCK BY LIGHTNING. 81 
 
 metal in the bells down to the works of the clock : 
 the only traces left in this course, were a little fusion 
 of the brass screws, and of the iron at the union of 
 the joints. The discharge, on reaching the works 
 of the clock, melted a small copper wire by which 
 the lever handle key was suspended on the iron 
 frame : it now spread over the wheels and other 
 parts, magnetized the steel pivots, blackened the 
 silver face of the regulator, and burst open the door 
 of the outer wooden casing, it did not, however, 
 stop the clock. The discharge, on leaving trfese 
 conductors, forced a passage through the floor of the 
 clock-room G by the assistance of some metal clamps, 
 into the ringing chamber R, leaving the floor as if 
 blown up by gunpowder. Coming out just over 
 one of the iron window-frames w, it shattered all 
 the glass in the window by the violent concussion, 
 and left marks of fusion on small streaks of lead in 
 the joints of the stones. By this course it reached 
 the lead of the roof at M, and slightly fused it at the 
 point on which the discharge first fell. After this 
 it became dispersed upon the earth without further 
 damage, by the large masses of metal and pipes con 
 necting the roof with the ground. 
 
 It is impossible to conceive a case giving a better 
 insight into the nature of disruptive discharges, 
 through a fortuitous arrangement of good and im 
 perfect conductors, than this now before us. In the 
 first place, we may observe that all the damage has 
 occurred in points where good conducting matter 
 ceases to be continued, as for example, between 
 4* 
 
82 ST. MARTIN S CHURCH STRUCK BY LIGHTNING. 
 
 the termination of the vane- rod at c and the clock- 
 faces at c and/ and again between the works of the 
 clock at G- and the lead of the roof at M, whilst the 
 course of the discharge in the irregular line Acs def 
 BGWM, is so marked and definite, and so inde 
 pendent of bodies not contributing to assist its pro 
 gress, that we perceive it actually passing down the 
 small iron rod / G within a few inches of the bells, 
 without affecting in any way these large metallic 
 masses, or disturbing the wooden case by which the 
 rod was surrounded. The discharge in passing upon 
 the dials, selected the north and west faces as afford 
 ing the easiest line of transit, and as the minute 
 hands only could contribute to the conduction, being 
 at the time in a position to transmit it to the centre 
 of the dial, these only were affected ; the hour hands, 
 although in continuation with the lower part of the 
 dials, were evidently without the line of action : the 
 course of the discharge, therefore, became diverted 
 at right angles nearly from the line of the hands in 
 order to pass upon the line of metals within the 
 tower, thus completely coinciding with the phe 
 nomena of artificial discharge.* 
 
 * Every care has been taken to verify the facts of this case. 
 Mr. Watkins, Optician, Charing Cross, London, well known as a 
 careful observer of such phenomena, made a personal observation 
 of the spire soon after the lightning fell on it, and very kindly 
 furnished the result of his inquiries. Mr. R. Dyer, of the Norfolk 
 Hotel, Surrey-street, also devoted much attention to the subject, 
 and obtained from those immediately connected with the church 
 every particular that could be desired. Mr. Newberry, the steeple- 
 keeper, Mr. Hennings, the builder, and Mr. Langstaffe, who re- 
 
BRIXTON CHURCH STRUCK BY LIGHTNING. 83 
 
 Brixton Church, struck by Lightning, ^th April, 1842. 
 
 The course of this discharge is traced in fig. 13, 
 which represents a section of the tower. There is a 
 metallic cross v on the summit of the dome ; this 
 cross is of sheet copper, four and a half feet in height, 
 and five inches square, and is supported by an iron 
 bar, which passes within the cross through the 
 masonry of the dome, and is secured by a nut at N. 
 The masonry of the dome is very massive, and the 
 joints of the stonework are strengthened by lead 
 solderings. The dome is supported by stone columns 
 about twelve feet high, as at M. Immediately under 
 the cupola is the clock-room c, the roof of which is 
 of wood covered with lead ; c is the position of the 
 clock: the works communicate with the dial-plates 
 by means of iron rods, as D c half an inch in diame 
 ter. D is the position of one of the four clock-faces ; 
 the dial-plates are of sheet copper, about four feet in 
 diameter, and the figures for the hours, &c., are 
 covered with leaf gold. The works of the clock 
 communicate with two bells at B by a small iron 
 wire about thirty feet long, and one-tenth of an inch 
 in diameter ; this wire is not continuous, but made 
 up of several pieces looped together ; it is supported 
 by means of small staples against an upright of wood. 
 Trie bells at B are very close to each other : they are 
 
 gilt the vane, <fec., gave freely all the information in their power. 
 T. Morris, Esq. architect, also contributed much valuable infor 
 mation. 
 
84 
 
 BRIXTON CHURCH 
 
 quite clear of the walls and the floor, and the larger 
 one is always in connection with the clock by the 
 wire / i, in fact, the striking weight rests on it, 
 being raised by the wire to strike the hour. Beneath 
 
 the belfry B is a room E communicating with it by a 
 trap ; there is an iron clamp, i, under the floor, about 
 fifteen inches from the bell, and immediately outside, 
 
STRUCK BY LIGHTNING. 85 
 
 at about a foot distant, is the base of one of the orna 
 mental columns T, which surround the middle portion 
 of the tower. There are sixteen of these columns, 
 and they are about eighteen feet long. At the base 
 of column T is the lead-work ra descending over the 
 roof, and connected with the earth by metallic gutters 
 and pipes. On reviewing the position of these differ 
 ent parts, we cannot but be struck with the analogy 
 in their electrical relation to similar parts in St. 
 Martin s spire, just described ; we should according 
 ly expect to find precisely similar effects, and such is 
 really the case, the course of the discharge being as 
 follows. 
 
 The explosion fell first on the cross v, and follow 
 ed it down to the masonry of the dome ; there it 
 diverged and rent the dome completely open, then 
 finding its way along the inner side of one of the 
 columns M, it slightly damaged the stone- work in the 
 vicinity. It now reached the metals on the dials, 
 and passed to the works of the clock at c by the iron 
 rods D c, and from thence along the wire and wooden 
 upright fi to the bell B ; this wire was knocked to 
 pieces, and portions of it dissipated. From the ter 
 mination of the wire it burst upon the floor and 
 clamp at i, as the shortest and easiest course to the 
 lead m on the roof of the church. Exploding upon 
 this point, it produced, by a common law of electrical 
 action, so much expansion as to shatter the base of 
 the column T ; the wood of the floor also at the 
 clamp i was torn up, as in St. Martin s spire, but 
 with less damage ; after this the discharge found its 
 
86 ST. BRIDE S CHURCH 
 
 way to the earth, with but little further difficulty. 
 The interrupted circuit traceable here, is represented 
 by the irregular line V u M D cfi T, &c., and the dis 
 ruptive discharge is precisely of the same character 
 and description as that just described (p. 82).* 
 
 In every instance of damage to buildings or ship 
 ping by lightning, the course of the electrical dis 
 charge is determined in a similar way, through points 
 presenting the least resistance to its progress, and the 
 mischief invariably occurs between detached masses 
 of metal. The beautiful steeple of St. Bride s Church 
 in London, struck by lightning in June, 1764, fur 
 nishes a most remarkable instance of this. The spire 
 of this steeple, where it rises above the belfry, is 
 composed of four stories of different orders of archi 
 tecture, beside the obelisk immediately over them. 
 The stone piers of these stories are connected together 
 and strengthened by horizontal iron bars ; near the 
 height of the capital of the pilasters, each story has a 
 set of four bars, placed crosswise, and tied together 
 by chain bars within the stone work. The obelisk 
 
 * The facts connected with this case have been minutely detail 
 ed by Mr. C. V. Walker, and there is not the slightest doubt of their 
 accuracy. It is, however, proper to observe, that in the account 
 given by Mr. Walker, he supposes a great portion of the charge to 
 have passed outside the building by an iron pipe, because the 
 damage done at the point i was not, he thinks, adequate to the 
 force of the shock as experienced at the base of the column T. This 
 supposition, however, is not warranted by any trace of the discharge 
 in the direction Mr. Walker has pointed out, and must, therefore, be 
 BO far regarded as hypothetical. His account of this case, however, 
 is singularly clear and instructive. 
 
STRUCK BY LIGHTNING. 8*7 
 
 terminates in seven courses of stone, the five upper 
 ones being connected together at the top and bottom 
 by iron collars soldered with lead. An iron bar, 
 about twenty feet in length and two inches square, 
 passes through these for about ten feet in a groove 
 cut through the middle of the solid stones and 
 filled in with lead. This bar rests in the two solid 
 stones of the lower courses, in which it is sunk 
 five inches deep, and is further secured by melted 
 lead. The upper part of the bar is cylindrical, 
 and covered for about ten feet by a ball and cross, 
 and by a vane, all of gilded copper. To lessen the 
 quantity of stone in this beautiful structure, cramps 
 of iron are employed in several places, on which 
 ornamental stones are placed. Other iron bars are 
 also employed to support the top of the windows, so 
 that a more complete series of discontinuous metallic 
 bodies intermixed with imperfect conducting matter, 
 cannot well be conceived. 
 
 When the lightning struck this steeple, it made 
 successive leaps between these metallic bodies, rend 
 ing and tearing up the masonry at the points where it 
 entered and again left them ; so that it was requisite 
 to rebuild eighty-five feet of the spire. One of the 
 iron bars in the composite story was found broken 
 in two, and another bent to an angle of nearly forty- 
 five degrees. No damage whatever was done to the 
 iron spindle, the vane or cross, or to the solid stones 
 through which the iron bar passed. The gilding on 
 the top of the cross, at the place where the discharge 
 first struck, was the only part affected; this was 
 
88 
 
 either dissipated or discolored: a little solder also 
 was melted at this spot, which appeared as if acted 
 on by fire. The lightning, it is clear, entered here 
 upon the whole metallic mass, and was quietly con 
 ducted to the termination of the iron spindle in the 
 two lower courses of stone : its destructive operation 
 now commenced, and the destruction was repeated 
 at each successive leap between the disconnected 
 metallic substances employed in the construction 
 of the spire. The last trace of it was at the west 
 window of the belfry, from whence it appears to 
 have found an adequate conduction to the earth.* 
 
 Before concluding these notices, it may not be 
 unimportant to detail, briefly, two cases of damage 
 by lightning which exhibit in a remarkable way its 
 destructive effects at sea and on shore, and show still 
 farther, the absolute necessity of guarding against 
 them. 
 
 The frontispiece represents the condition of the 
 Thisle, an English frigate, struck by lightning in 
 January 1Y86, near the Scilly Isles, during her pas*- 
 sage from Lisbon to England. The weather at the 
 time was tempestuous and squally, with showers of 
 hail, so that the ship was hove-to under storm stay 
 sails, f The electrical discharge, after disabling seve 
 ral of the crew, struck on the mainmast, and set the 
 sails and rigging on fire : it also struck the foremast 
 and shivered it. ^ To get clear of the burning mass,- 
 
 * Phil. Trans, for 1764, pp. 201 and 227. 
 f Ship s log. \ Idem. 
 
NATURE OF LIGHTNING RODS. 89 
 
 the master cut one of the lanyards of the main 
 shrouds to windward, when the force of the gale 
 carried the whole over the side, together with the 
 mizen-topmast ; the fore-topmast soon followed, so 
 that the ship was left almost a total wreck. The 
 electrical discharge knocked down several of the 
 crew near the guns, and swept the decks. * 
 
 PRACTICAL RESULT OF THE PRECEDING 
 INQUIRIES. 
 
 Nature of Lightning Rods. 
 
 The damage sustained by buildings and ships m 
 thunderstorms being invariably found to occur in 
 the spaces where good conductors of electricity cease 
 to be continued, it became an important question in 
 practical science, how far it would be desirable to 
 provide at once a continuous line of conduction, 
 through which the electrical discharge might be trans 
 mitted without any intermediate explosion, and con 
 sequently without damage to the general mass. An 
 idea first suggested by the American philosopher, 
 
 * A similar result ensued in the Lowestoffe, a sister ship, in the 
 Mediterranean, in 1796. This frigate was also dismasted, and left 
 a mere wreck. 
 
90 NATURE OF LIGHTNING RODS. 
 
 Franklin, and since carried effectually into practice 
 under the form of a lightning rod. 
 
 The application of such a rod to a building or 
 ship, is evidently equivalent to the uniting into a 
 continuous conducting train, all the detached metallic 
 masses between which damage ensues, and in the 
 case of particular buildings, into the construction of 
 which such masses do not enter, it supplies the de 
 gree of conducting power requisite for their safety. 
 A conducting rod, therefore, in whatever way it may 
 be applied, is to be considered merely as a means of 
 perfecting the conducting power of the whole mass, 
 so as to admit of intense discharges of lightning being 
 securely transmitted, which otherwise would not pass 
 without intermediate explosion and damage ; for it 
 must never be forgotten, as an important feature in 
 the consideration of this question, that the materials 
 of which buildings and ships are composed, are for 
 the most part such as come under the denomination 
 of conductors (p. 8) ; the whole fabric is, therefore, 
 to a greater or less extent, an electrical conductor. 
 Now the chance of its escaping damage from a dis 
 charge of lightning, increases with its power of trans 
 mitting the electrical action by which it is assailed. 
 If we could suppose a ship or building to have a 
 perfect conducting power in all its parts, or if we 
 imagine it to be metallic throughout, then damage 
 from lightning would be unknown. Thus discharges 
 of lightning struck repeatedly on the iron steamboat 
 which accompanied Lander in his last attempt to ex 
 plore the interior of Africa, without producing the 
 
NATURE OF LIGHTNING RODS. 91 
 
 slightest effect on it ; whilst vessels built of wood 
 and metal were damaged. A man in armor would 
 certainly be safe in a thunderstorm, from the great 
 conducting power of the metal as compared with the 
 human body. The great object, therefore, to be at 
 tained in the application of lightning conductors to 
 the defence of buildings and shipping from lightning, 
 is to bring the general mass as nearly into this state 
 as possible. 
 
 It has already been observed (p. 9), that Mr. Cav 
 endish determined the conducting power of iron to 
 be, in relation to that of water, as four hundred mil 
 lions to one. Taking therefore the conducting power 
 of water as unity, and assuming it as the value of 
 the mean conducting power of the general mass of a 
 building, which is upon the whole not far from the 
 truth, then, by giving a building a lightning conduc 
 tor of great capacity, and connecting it with the de 
 tached masses of metal as far as is possible, we mul 
 tiply its chance of escaping damage, in the interme 
 diate points in which the conductor is applied, four 
 hundred millions of times ; and considering that by 
 the laws of electrical action, the electrical discharge 
 finds its way through any line or lines, which upon the 
 whole offer the least resistance to its passage, nothing 
 can be clearer than the deduction, that any incapa 
 city of the building as a whole, to transmit the charge 
 through its parts without explosion, would be sup 
 plied by the presence of the conductor ; and hence 
 this multiplied chance of escape applies equally to 
 the whole building. It is therefore demonstrable by 
 
92 LAWS OF ELECTRICAL CONDUCTION. 
 
 physical facts, that perfect security is to be derived 
 from an efficient conductor properly applied. 
 
 The first lightning conductor seen in England, 
 was erected by Dr. Watson at Payneshill, in 1762. 
 In 1769 the Jacob tower at Hamburg was defended 
 by a lightning rod, and after the cathedral church at 
 Sienna had been repeatedly damaged by lightning, a 
 similar means of protection was employed there also. 
 The inhabitants at first regarded the rod with terror 
 and apprehension, and called it a Heretic Hod ; but 
 on the 10th of April, 1777, a thunderstorm occurred, 
 and there fell on the tower a heavy stroke of light 
 ning, which was carried off by the rod, without 
 doing the slightest damage even to the gilded orna 
 ments near which it passed.* The inhabitants now 
 began to look on the heretic rod with more confi 
 dence ; and it is an important fact, that this church 
 does not seem to have suffered from lightning since. 
 
 Laws of Electrical Conduction. 
 
 The heating effect of the same, or different quan 
 tities of electricity, on metallic wires of the same or 
 different diameters, is as the square of the passing 
 quantity of electricity directly, and as the square of 
 the diameter of the wire inversely. Thus the heat 
 developed by a passing shock is four times as great 
 when the quantity of electricity is doubled, and only 
 one-fourth as great when the diameter of the wire is 
 doubled. A metallic rod, therefore, of twice the di- 
 
 * MARBUCH, EnJcyklopcedie, vol. i., p. 314. 
 
LAWS OF ELECTRICAL CONDUCTION. 93 
 
 ameter, conducts twice the quantity of electricity 
 with the same development of heat. Taking the 
 heat evolved as proportionate to the resistance, we 
 may conclude, that the conducting power of a me 
 tallic body varies with the area exposed in cutting it 
 transversely to its length ; that is to say, with the 
 area of its section, since this is proportionate to its 
 solid contents. 
 
 In estimating the resistance of a metallic body 
 to the transmission of a shock of electricity, we have 
 also to take into consideration the distance traversed. 
 Now the resistance to electrical transmission through 
 a metallic wire, has been found to increase with the 
 length of the wire ; that is to say, the resistance to 
 the transmission of the charge was twice as great 
 when the length of the conductor was doubled ; a 
 law observable from one hundred up to one thousand 
 feet in length. A lightning conductor, therefore, 
 should have its dimensions increased, when required 
 to be of considerable extent. 
 
 The explanation of the above general laws seems 
 to be this : supposing a given quantity of electricity 
 to fall on a single metallic particle, and to experience 
 a given resistance to its progress, then this resistance 
 would be diminished by placing a second particle 
 by the side of it, for the charge would be divided 
 between the two. If two other particles were added, 
 we may conceive it to be still further reduced in pro 
 portion to the number of particles sharing in the 
 conduction. Now, in the case of the section of a 
 metallic wire, the diameter of which is double that 
 
94 MECHANICAL EFFECTS OF 
 
 of another, there are four times the number of par 
 ticles, hence the resistance with the same quantity 
 of charge is reduced to one-fourth. In a similar way 
 it may be shown, that by increasing the length of 
 the conductor, we continually increase the number 
 of particles to be passed through, hence the resist 
 ance through twice the length will be twice as great, 
 through three times the length three times as great, 
 and so on. In the case of the quantity of electricity 
 being increased, we have the resistance dependent 
 not only on the increased charge, but also on its in 
 creased force. Thus a particle of metal conducting 
 a double quantity of electricity is subject to a double 
 force, since it is quite reasonable to conclude that 
 the forces (p. 17) with which the opposite electrical 
 powers tend to unite, would increase with the amount 
 of disturbance. 
 
 Mechanical Effects of the Electrical Discharge. 
 
 But it is not only the heating effect of the dis 
 charge we have to consider ; it is necessary to take also 
 into the account its more mechanical effects, indeed, 
 it is the expansive action which produces the great 
 mass of damage by lightning so commonly observed. 
 If a powerful shock of electricity be transmitted by 
 a fine wire, the wire will very often appear crippled 
 throughout its length, and will exhibit a series of zig 
 zag creases. And if a similar shock be passed be 
 tween two metallic balls in a confined portion of air, 
 the air will be caused to expand with great violence, 
 
 
THE ELECTRICAL DISCHARGE. 95 
 
 so as to frequently burst open the containing vessel. 
 Light bodies such as wafers will become dispersed in 
 all directions, when exposed to the expansive effect 
 produced by the electric shock in passing through- a 
 short interval of air. 
 
 At the time the steeple of St. Bride s church, 
 London, was struck by lightning, in June, 1764, it 
 is stated by Mr. Delaval, F.E.S., who communicated 
 a most interesting detail of the circumstances to the 
 Royal Society, that "the lightning acted as an elastic 
 fluid," and that "the effects are exactly similar to 
 those which would have been produced by gunpow 
 der, pent up in the same places and exploded. A 
 stone weighing about seventy pounds was thrown to 
 a distance of fifty yards; an iron bar half an inch 
 in thickness, and about two feet in length, joining 
 some of the masonry of the tower, was not only 
 broken in two, but one part of it, according to 
 Dr. Watson,* was actually bent to an angle of 
 45." 
 
 The mechanical effects of lightning, seen in 
 piercing solid bodies with holes, in splitting them 
 in pieces, and in projecting their fragments (some 
 times of enormous weight) to great distances, are so 
 well known, and so generally admitted, that it will 
 be needless to multiply instances in proof of it ; but 
 a circumstantial statement of some remarkable cases 
 of this kind may throw light upon the manner in 
 which the electric fluid acts. 
 
 * Phil Trans, for 1764. 
 
96 MECHANICAL EFFECTS OF 
 
 In the autumn of 1778, lightning struck the house 
 of CassellF, an engineer, at Alexandria. It did no 
 damage, but pierced the panes of glass in the windows 
 with several small holes about the sixth of an inch in 
 diameter. Small cracks in the glass diverged from 
 these holes as centres. 
 
 In August, 1777, lightning struck the steeple of 
 the parish church of St. Sepulchre at Cremona, broke 
 the iron cross which surmounted the tower, and pro 
 jected to a distance the weathercock, which revolved 
 under the cross, and which was made of copper, 
 tinned, and coated with oil-paint. 
 
 This weathercock was found to have been pierced 
 with eighteen holes , nine of which were very prom 
 inent on one side, and the other nine on the other. 
 As there was no appearance of more than one stroke 
 of lightning, all these holes must be supposed to 
 have been pierced at once. The position of the 
 holes are such as would have been produced by 
 blows imparted simultaneously in opposite directions 
 on parts of the metal nearly contiguous, and the in 
 clination of the beards or projecting edges of the 
 holes on one side correspond exactly with those on 
 the other, the directions of all the eighteen beards 
 being parallel. 
 
 On the 3d of July, 1821, lightning struck a house 
 at Geneva, and pierced the tin which covered a part 
 of the roof with several holes, leaving evident marks 
 of fusion. One piece of tin in particular, which 
 covered the angle made by a chimney with the sur 
 face of the roof near it, was pierced with three nearly 
 
THE ELECTRICAL DISCHARGE. 97 
 
 circular holes, about an inch and three quarters in 
 diameter, and about five inches apart, measured from 
 centre to centre. The metal at the edges of these 
 holes was bent, as it would have been by a force 
 bursting through it in one direction or the other. 
 The edges of the two holes were bent on contrary 
 sides. 
 
 On the night between the 14th and 15th of April, 
 1718, the church of Gouesnon, near Brest, was struck 
 by lightning with such force that it shook as if by 
 an earthquake. The stones of the walls were pro 
 jected in all directions to a distance of from fifty to 
 sixty yards. 
 
 The lightning which formally struck the Chateau 
 of Clermont, in Beauvoisis, made a hole twenty-six 
 inches wide and the same depth in the wall ; the 
 date of the building of which was so far back as the 
 time of Ca3sar, and which was so hard that a pickaxe 
 could with difficulty make any impression upon it. 
 
 On the night between the 21st and 22d of June, 
 1723, lightning struck a tree in the forest of Nemours. 
 The trunk was split into two fragments, one seven 
 teen, and the other twenty-two feet long. These 
 fragments, so heavy that one of them would require 
 the combined strength of four men, and the other 
 that of eight men, to lift it, were, nevertheless, pro 
 jected by the lightning to the distance of about 
 seventeen yards. 
 
 In January, 1762, lightning struck the church of 
 Breag, in Cornwall, the southwest pinnacle of the 
 tower of which it destroyed. A stone, weighing one 
 5 
 
98 MECHANICAL EFFECTS OF 
 
 hundred and seventy pounds, was projected from the 
 roof of the church to a distance of sixty yards in the 
 direction of the south. Another fragment of stone 
 was projected to the north to a distance of 400 yards. 
 A third was projected to the southwest. 
 
 About the middle of the last century, a rock of 
 micaceous schist, measuring 105 feet long, 10 feet 
 wide, and about 4 feet thick, was struck by lightning 
 at Funzie, in Scotland, and was broken into three 
 principal fragments, not counting smaller pieces. 
 One of these fragments twenty-six feet long, ten feet 
 wide, and four feet thick, had been merely inverted 
 in its position. Another, 28 feet long, 7 feet wide, 
 and 5 feet thick, was projected over the hill to a dis 
 tance of fifty yards. The remaining piece, forty feet 
 long, was projected in the same direction, with still 
 greater force, and fell into the sea. 
 
 On the 6th of August, 1809, at Swinton, about five 
 miles from Manchester, lightning struck the house of 
 Mr. Chadwick, at 2 P. M. A sulphurous vapor im 
 mediately filled the house. The external wall of a 
 building erected against the house as a coal-shed, was 
 torn from its foundations, and raised in a mass. It 
 was transported, maintaining its vertical position, to 
 some distance from its original place ; one of its ends 
 was transported nine and the other four feet. This 
 wall thus raised and transported, was composed of 
 seven thousand bricks, which, independent of the 
 mortar by which they were cemented together, 
 -would have weighed about twenty-six tons. This 
 wall was eleven feet high and three feet thick, and 
 
THE ELECTRICAL DISCHARGE. 99 
 
 its foundation was about a foot below the level of the 
 ground. Above this coal-shed was a cistern, which, 
 at the time of the phenomenon, contained a quantity 
 of water, and the shed contained about a ton of coals.* 
 
 The first Presbyterian church in the City of 
 Syracuse, New- York, was struck by lightning. The 
 church had lightning rods attached, but these were 
 improperly fastened to the walls by sharp-pointed 
 staples in full connection with the main rod. The 
 lightning struck the spire, ran down part way, when 
 the charge divided, following a staple fastening into 
 the building, as far as the pointed staple extended. 
 This staple terminating in the dry, hard masonry, 
 which must have been nearly a non-conductor, the 
 charge blasted out a portion of the steeple, throw 
 ing the broken fragments several hundred feet, 
 much after the manner of a too shallow blast in a 
 rock. And thus the beautiful structure was saved 
 the dire destruction which must have happened had 
 the church been built of wood, a partial conductor 
 when wet, and fastened with iron bolts, &c. These 
 facts were related to the writer a few months since 
 by several intelligent and respectable citizens of that 
 city, who were eye-witnesses to the accident, each of 
 whom saved pieces that were thus blasted out of the 
 steeple. The mechanical force here manifested was 
 precisely like that of gunpowder. 
 
 In the shock of lightning which fell on His 
 Majesty s ship Elephant, of seventy-four guns, at 
 
 * Dr. Lardner s Lect. on Science and Art, vol. ii. p. 69. 
 
100 MECHANICAL EFFECTS OF 
 
 Portsmouth, in November, 1790, all the iron hoops 
 and wooldings on the mainmast were burst open 
 and broken in pieces, and some of the parts scat 
 tered to great distances. Some of these hoops were 
 half an inch thick, and five inches wide ; the mast, 
 although of immense size, being about three feet in 
 diameter, and upwards of 110 feet in length, was 
 entirely shook and shivered throughout.* Now, in 
 these cases we do not find any melting of the iron 
 work : we observe only the effects of a terrific me 
 chanical power. 
 
 Another remarkably interesting instance of this 
 effect was observed in the case of His Majesty s ship 
 Desiree, already alluded to (p. 55), struck by light 
 ning in Port Antonio, in Jamaica, in the autumn of 
 1803. Admiral Eoss, who then commanded the 
 ship, states, that one part of the main-topmast was 
 found on the following morning sticking in the mud 
 on one side of the harbor, and another part in a 
 timber-yard on the opposite side. 
 
 In the application of lightning conductors to 
 buildings, therefore, we have to consider the effect 
 likely to be produced on them by the mechanical 
 action of the shock, by which they may be disjointed, 
 twisted, or rent asunder in various ways. Thus, the 
 small conductor of linked brass rod, at Charles 
 Church, Plymouth, struck by lightning in December, 
 1824, was literally torn in pieces and disjointed, 
 and many of the links twisted into the shape of the 
 
 * Naval Chronicle. 
 
THE ELECTRICAL DISCHARGE. 101 
 
 letter S. A part of the small wire rope applied as 
 a conductor to the Hotel des Invalides at Paris was 
 broken into small pieces an inch or more in length, 
 and scattered in all directions by the lightning 
 which fell on that building in June, 1839. This 
 conductor consisted of about twenty iron wires 
 twisted together as a rope ; the lead surrounding 
 the lantern was torn up and scattered, but without 
 any signs of fusion.* 
 
 The intensity of electrical accumulation having 
 been found to decrease in an inverse ratio of the 
 square of the opposed surfaces, some electricians 
 were led to imagine that extent of surface was the 
 great desideratum in the application of a lightning 
 conductor. This decrease of intensity, however, 
 does not affect the conditions of conduction as 
 regards the heating effect of the discharge, for, 
 whether the quantity of electricity be accumulated 
 on a large extent of surface, or on a small one, the 
 
 * Comptes Rendus, June 17, 1839. 
 
 A question of no small public interest arises here relative to the 
 insurance of buildings against lightning, which has been assumed to 
 be a species offre, and that hence all buildings damaged by light 
 ning are damaged as if by fire : but this is certainly not the case. 
 A building may be struck by lightning, and may certainly be set 
 on fire by it ; but in the great variety of cases which occur, the 
 damage is purely of a mechanical kind: thus, in the case of the 
 spire of St. Martins, already described, no damage could be said to 
 have arisen from fire, and consequently no responsibility could 
 attach to those who assured it against fire only ; the damage was 
 purely mechanical, arid must be classified with the kind of 
 damage occurring from a heavy gale of wind, or any other me 
 chanical force. 
 
102 MECHANICAL EFFECTS OF 
 
 heating effect, when the discharge does occur, is 
 always the same. Whatever may be the distance 
 at which the neutralization of the forces begins, they 
 always unite with precisely the same degree of 
 power, the quantity of electricity being the same. 
 
 This question, so frequently discussed, has not 
 been fully appreciated in all its details, for although 
 quantity of metal is an essential condition of a light 
 ning rod, yet it is likewise desirable to place the 
 metallic particles under as great an extent of surface 
 as may be consistent with strength and durability, 
 in order to keep down the intensity of the shock, 
 and diminish the mechanical action. We may, in 
 fact, for the moment, consider a conductor, while in 
 the act of carrying off a charge of lightning, as an 
 electrified body. Its electrical intensity, therefore, 
 is very much less with a large surface than with a 
 small one : hence, by extent of surface, we diminish 
 the activity of the passing charge, and tranquillize 
 its mechanical effect on the conductor. Thus we 
 find, in a variety of cases of damage by lightning, 
 that the passing charge, in striking on large ex 
 panded sheets of metal, has become comparatively 
 tranquil, and has been traced no further, whilst in 
 striking on larger masses of metal, exposing but a 
 small surface, it has assumed an intensely active 
 state. The flash of lightning which struck His 
 Majesty s ship Badger, lying in the Medway, in 
 August, 1822, vanished, after striking upon the 
 copper lining of the galley, although just before, it 
 had penetrated the mast, rent the copper, and melted 
 
THE ELECTRICAL DISCHARGE. 103 
 
 the lead over the heads of two large bolts in the 
 deck beams. 
 
 Although the general tendency of a discharge of 
 lightning is always through the conductor, as being 
 the line of least resistance (p. 69), yet there may 
 arise cases in which the electrical forces may be so 
 circumstanced as to affect other lines of action near 
 it, and in which damage may ensue. Thus, in the 
 French frigate Calypso, fitted with a wire conductor 
 of small surface, two men in the main chains, who 
 were standing in a slightly interrupted conducting 
 communication between the wire and the sea, were 
 struck senseless. A similar case is related by M. 
 Arago, as having occurred in the French frigate 
 Junon. In fact, wherever from any cause the re 
 sistance in the direction of the conductor is con 
 siderable, the chances of damage in some other 
 direction become multiplied. Thus, a case occurred 
 at Bayonne, in which the length of the conductor 
 was unnecessarily increased, that is to say, instead 
 of terminating at once in the ground, it was led off 
 at the foot of the building on semi-insulating stakes of 
 wood for some distance ; the charge here divided upon 
 other lines near the conductor, and caused damage.* 
 Provided the quantity of metal be present, the 
 form under which we place it is evidently of no con 
 sequence to its conducting power, f since it would be 
 
 * Annuaire pour 1838, p. 597. 
 
 f The reader will observe that the writer is speaking of the capa 
 city of metal to conduct a given amount of electricity, without regard 
 to power to disperse or weaken the charge by edges and points. 
 
104 MECHANICAL EFFECTS OF 
 
 absurd to suppose that a mass of metal, under any 
 form, did not conduct electricity in all its particles, 
 indeed, we know that it does so, and that it is im 
 possible to fuse by electricity a portion only of a 
 homogeneous metallic plate of uniform thickness. 
 Again, if the heating effect of a given quantity of 
 electricity on a metallic wire be measured, and then 
 the wire be rolled out into a flat surface, or otherwise 
 drawn out and placed under the form of two or more 
 smaller ones, still the same heat will be evolved 
 when conducting the same charge ; * there is conse 
 quently no disadvantage in giving a lightning rod as 
 much superficial capacity as possible as regards con 
 ducting power, whilst, on the contra^, the dimin 
 ished intensity attendant on it is very advantageous: 
 this effect of superficial conductors appears to depend 
 on the removal of the electrical particles further out 
 of the sphere of each other s influence. In a dense 
 solid rod they may be supposed to be in a state of 
 compression, in each other s way, as it were, 
 whereas, by expanding the same quantity of metal 
 into a larger surface, we immediately free them from 
 this condition, and allow them greater space, f 
 
 In order, therefore, to resist the heating effect, we 
 require quantity of metal ; to restrain the electrical 
 intensity, and to diminish the mechanical force, we 
 require extent of surface. The distinction is nice, 
 but it is a very important one. 
 
 * Trans. Royal Society for 1827. 
 
 f See Phil Trans, for 183-4 and 1836, pp. 232 and 450, for some 
 further inquiries on this point by the author. 
 
THE ELECTRICAL DISCHARGE. 105 
 
 Two questions here present themselves which de 
 mand attentive consideration, viz., what quantity of 
 metal is requisite to perfect securit}^ and to what ex 
 tent will a lightning rod afford protection, in other 
 words, what is the sphere of its influence ? These 
 problems, although apparently difficult, admit of a 
 satisfactory solution a solution, it is true, depending 
 on the results of experience, but still perfectly con 
 clusive ; for it is here to be remembered, that we seek 
 protection not against discharges of lightning which 
 have no existence out of the imagination, but against 
 such as have fallen within the experience of man 
 kind n ot against convulsions of nature, in which it 
 would probably be of little consequence whether we 
 had lightning rods or not, but against probable 
 and tangible results of the operation of a given nat 
 ural agency, with the laws of which we are ill ac 
 quainted. Now, we have the recorded experience 
 of more than a century to guide us in this inquiry ; 
 and first, with respect to the actual quantity of elec 
 tricity which may be contained in a flash of light 
 ning, and the quantity of metal requisite to resist 
 its effects. 
 
 What quantity of Metal is requisite for a Lightning 
 Rod ? 
 
 Perhaps one of the most terrific discharges of 
 lightning ever experienced, was that in the case of 
 the New- York packet, struck by lightning in the 
 5* 
 
106 QUANTITY OF METAL REQUISITE 
 
 Gulf Stream, in April 1827, already noticed (p. 54). 
 In this case the discharge fell on a pointed iron rod 
 four feet long, and half an inch in diameter ; some 
 few inches only of the rod near its point were melted ; 
 the linked iron chain which descended from this rod 
 to the water, about a quarter of an inch in diameter, 
 was knocked in pieces by the expansive force of the 
 shock, and some of the links fused. The flash of 
 lightning not only melted some of the links, but 
 " caused them to burn like a taper." " The melted 
 iron fell in glowing drops upon the deck, which was 
 instantly set on fire wherever the burning matter 
 fell." " Such was the violence of the shock, that the 
 ship recoiled, or, in sea phrase, lurched so strongly, 
 as to throw down the people on the deck."* The 
 results of a great natural experiment are here pre 
 sented to us, and we see that an iron rod of half an 
 inch in diameter, effectually resisted a flash which 
 fused and destroyed a chain of about one half of its 
 dimensions. 
 
 The flash of lightning which struck Her Majesty s 
 ship Rodney, in December 1838, was so powerful 
 that it quite dispersed the topgallant-mast in small 
 chips, covering the sea with splinters, set fire to the 
 main-topsail, tore a piece ten feet long out of the 
 topmast, burst thirteen hoops on the mainmast, each 
 five inches wide and half an inch thick, and traversed 
 the mast with destructive effect for fifty-three feet. 
 Now this charge passed without fusion on the cop- 
 
 * lie-port of Commission on Shipwreck by Lightning. 
 
FOR A LIGHTNING ROD. 107 
 
 per funnel, sixteen inches long, ten inches in diame 
 ter, and less than a quarter of an inch thick, belong 
 ing to the topgallant rigging. 
 
 In September 1833, two successive discharges of 
 lightning fell on His Majesty s ship Hyacinth, in the 
 Indian Ocean, and descended by the fore and main 
 masts to the sea. The topgallant and topmasts 
 were literally shaken into a bundle of laths, so that 
 they could scarcely be supported ; the topmasts thus 
 shivered were from eleven to twelve inches in di 
 ameter and about forty feet in length. This destruc 
 tive shock was safely conducted away from the ter 
 mination of the topmasts by a chain sheet fifty feet 
 long, made of iron rod half an inch in diameter, and 
 finally through the ship by a copper pipe, three 
 inches in diameter, one-eleventh of an inch thick, 
 and ten feet long ; * before reaching these bodies, 
 which were direct conductors to the sea, the discharge 
 ravaged and destroyed the masts through a distance 
 of nearly eighty feet ; the chain did not show any 
 marks of fusion. 
 
 In the summer of the year 1760, a heavy dis 
 charge fell on a conductor fixed on a house in Phila 
 delphia. This conductor consisted of an iron rod, 
 half an inch in diameter ; it extended nine feet above 
 the chimneys, and terminated in an iron stake in the 
 ground. The part above the chimneys was tipped 
 with brass rod, about a quarter of an inch in diame 
 ter, and ten inches long. Mr. West, the owner of 
 
 * Report of Commission on Lightning Rods, p. 44. 
 
108 QUANTITY OF METAL REQUISITE 
 
 the house, judging from the crash that the conductor 
 had been struck, had it examined. About three 
 inches of the brass rod were observed to have been 
 fused, and some of the fused metal had sunk down 
 about the remaining part of the rod, forming a 
 rough, irregular cap about it. The house was not 
 damaged, nor were any further effects produced on 
 the conductor.* 
 
 On the 26th of January, 1838, a flash of light- 
 ning fell on Her Majesty s ship Dublin, of fifty guns, 
 at Kio de Janeiro. It was carried off by a conductor 
 of long copper links, each link being about a quarter 
 of an inch in diameter, and ten inches long. The 
 conductor was "regularly melted" in several parts; 
 these fell on the deck ; other parts, which remained 
 attached to the line supporting the chain along the 
 rigging of the ship, appeared as if they had been 
 exposed to a very fierce heat. This line was not 
 hurt, nor was any damage done to the rigging, f 
 
 A house was struck by lightning at Tenterden, 
 on the 17th of June, 1774. The discharge was con 
 ducted by an iron bar three-quarters of an inch 
 square, but produced no effect on it.J 
 
 In June, 1772, a discharge of lightning fell on 
 the Yicarage-house at Steeple Ashton, in Wiltshire. 
 The iron bell- wires in both the parlors and in the 
 
 * Phil. Trans., vol. liii. part 1. 
 
 f Report on Shipwreck by Lightning, p. 94. 
 
 i Phil. Trans, for 1775. 
 
FOR A LIGHTNING ROD. 109 
 
 hall were entirely dispersed, except in their twisted or 
 double portions* 
 
 In June, 1828, a heavy flash of lightning fell on 
 the spire of Kingsbridge church, in Devonshire, 
 and was received on an iron spindle, seven feet long, 
 and one inch in diameter, without producing the 
 least effect on it, or damaging the stones around it : 
 but on leaving the spindle, however, it shattered the 
 tower, and did considerable damage. 
 
 In the case of Charles church at Plymouth (p. 
 100), although the wire was knocked in pieces at the 
 points of junction, and considerably bent, it was not 
 materially damaged by fusion. 
 
 "In reviewing, in this way, a great variety of 
 cases in which buildings and ships have been ex 
 posed to appalling storms of lightning in various 
 parts of the world, and throughout a century of 
 years, we are enabled to appreciate the power of 
 metallic bodies to carry off lightning with safety. 
 Now we do not find in any of these cases that a con 
 ducting rod, or other mass of metal, equal in sub 
 stance or conducting power to a rod of copper half 
 an inch in diameter and six inches long, has ever 
 been fairly melted. On the contrary, heavy dis 
 charges have traversed rods of less dimensions with 
 safety." 
 
 Besides, the conducting power of lightning rods 
 has been much increased of late by improvements in 
 their construction. 1st. In multiplying the number 
 
 * Phil Trans, for 1773. 
 
110 EXTENT OF THE PROTECTING POWER 
 
 of their points. 2d. In perfecting their continuity. 
 3d. In the substitution of square rods for round 
 ones. The reasons of these facts will appear here 
 after. "We will here stop only to add, what Mr. 
 Harris, F. E. S., in his work on thunderstorms, 
 affirms, viz., " when an acutely terminated lightning 
 rod receives a charge of lightning, a very considera 
 ble portion of the charge, if not the whole, runs off 
 in an attenuated stream." 
 
 How far does the Protecting Power of a Lightning Rod 
 extend? 
 
 It is not easy to assign the limit of the protecting 
 power of a conductor. The French philosophers 
 consider it will afford protection over a circle equal 
 to twice its radius ;* this, although possible in cer 
 tain cases, is by no means a general truth. All the 
 experience we have of the operation of conductors 
 on discharges of lightning, tends to the conclusion, 
 that they have no influence whatever in determining 
 the course of such discharges, further than arises out 
 of the circumstance of their furnishing an easy line 
 of conduction. That they do not always afford pro 
 tection over any considerable distance, is clear from 
 the following cases : 
 
 Her Majesty s ship Endymion, commanded by 
 Captain the Honorable F. Grey, was struck by light 
 ning at Calcutta, in March, 1842. This frigate had 
 
 * Annales de Chimie et de Physique, vol. 26. 
 
OF A LIGHTNING ROD. Ill 
 
 a chain conductor on the mainmast, applied in the 
 usual way, not very dissimilar to that recommended 
 in the report of M. Gay Lussac to the Koyal Acade 
 my of Sciences at Paris. The electrical explosion, 
 instead of falling on the conductor, struck the fore 
 mast, shivered the top-gallant and topmast, and 
 damaged the lower mast. Now, in this case, the 
 mast struck was not above fifty feet distant from the 
 mainmast, which was furnished with a conductor, 
 and had a radius of one hundred and fifty feet.* 
 
 Her Majesty s ship JEtna was struck by several 
 heav}r electrical discharges at Corfu, in January, 
 1830. These, for the most part, passed down a 
 chain conductor attached to the mainmast. One of 
 the discharges, however, struck the ship near the 
 bow, and exploded about twelve feet above the fore 
 castle, close to the foremast, knocking down all the 
 people on deck, and doing other damage.f 
 
 The Board-house, at Purfleet, was struck by 
 lightning on the 12th of May, 1777,^: at a point up 
 wards of forty feet from the conductor with which 
 the house was furnished. The damage, it is true, 
 was small; a few stones fastened by iron cramps not 
 connected with the conductor were thrown down. 
 The Board-house was a lofty building, with a pointed 
 roof, well leaded, and connected by lead gutters and 
 pipes with the earth, and with wells forty feet deep, 
 for the purpose of conveying water forced up to a 
 
 * Ship s log, and private letter. 
 
 f Ship s log. J Phil. Trans. 
 
112 EXTENT OF THE PROTECTING POWER 
 
 cistern in the roof. It was therefore only thought 
 necessary to add an iron spike, about ten feet long, 
 to the middle of the highest part of the roof. About 
 one hundred and fifty yards from this building were 
 five powder magazines, each one hundred and sixty 
 feet long and fifty -two feet wide, having spiked con 
 ductors at each end, projecting ten feet above the 
 roofs, and connected with wells of water. It is quite 
 apparent here, that so far as relates to the influence 
 of a conductor over a given area, the experiment is 
 conclusive, and the result shows that we cannot al 
 ways calculate on the radius of protection ; thus con 
 firming the deductions already arrived at* (p. 72). 
 
 The Poor-house at Heckingham was struck by 
 lightning on the 17th of June, 1781, which damaged 
 one of the extreme corners of the building, situate 
 seventy feet from the pointed conductors with which 
 the house was furnished. Little or no damage, how 
 ever, was sustained. The house consisted of a cen 
 tral range of buildings and two flanks ; in general 
 form, approaching that of the letter H. There were 
 eight chimneys ; each had a pointed conductor. 
 The flash appears to have divided in this case before 
 reaching the ground (p. 35). One portion struck on 
 one of the conductors, and was carried off; a second 
 struck the extreme point of the building, and set it 
 011 fire; a third fell on the earth immediately in 
 front of it.f 
 
 The house at Tenterden. already referred to (p. 
 
 * Phil Tram, for 1773. f phil - Trans., vol. Ixxii., p. 377. 
 
OF A LIGHTNING ROD. 113 
 
 108), had two stacks of chimneys at each end. To one 
 of these stacks was fixed a conductor of iron rod, pro 
 jecting five feet above the chimney. Now, the dis 
 charge fell on one of the chimneys fifty feet distant, 
 at the opposite end of the building ; being the chim 
 ney diagonally opposite to that on which the con 
 ductor was placed, and on passing to the earth, it 
 did considerable damage. The whole of this shock 
 was finally concentrated on an iron bar three-quar 
 ters of an inch square, and produced no effect on it, 
 as already noticed (p. 108). The house was about 
 thirty feet wide.* 
 
 These cases evidently throw doubt on any theo 
 retical calculation as to the limit of distance, within 
 which a pointed lightning conductor will afford pro 
 tection, and confirm in a remarkable way the views 
 we have taken of electrical discharges from the at 
 mosphere (p. 69) 
 
 * Phil. Trans., 1775. 
 
SECTION III. 
 
 RESULTS OF THE APPLICATION OF LIGHTNING 
 RODS TO BUILDINGS AND SHIPS, 
 
 FROM THE PERIOD OF THEIR FIRST BEING EMPLOYED IN 
 THE YEAR 1760. 
 
 Introductory Remarks. Whether Metallic Conductors have effectu 
 ally defended Buildings, &c. against Lightning? Whether 
 Lightning Rods attract Lightning? Whether pointed Conduc 
 tors actually prevent explosions of Lightning ? The Phenome 
 na observed, when concentrated discharge strikes upon a Con 
 ducting Rod. Harmless character of the luminous appearances 
 observed on Lightning Rods. Division of the Charge. Instan 
 ces in which Buildings having pointed Lightning Rods are said 
 to have been damaged by Lightning. Precautions when exposed 
 to the action of Thunderstorms. Construction of Lightning 
 Rods applied to Buildings. Practical Deductions. Concluding 
 Observations. 
 
SECTION III. 
 
 Introductory Remarks. 
 
 IN the preceding sections we have considered the 
 physical conditions of a thunderstorm, and the laws 
 and mode of operation of electrical discharges. 
 From these inquiries we have deduced certain prac 
 tical results relative to the employment of metallic 
 substances under the form of lightning rods, as a 
 means of protection against the calamitous effects of 
 lightning. 
 
 We now propose to examine such evidence as 
 we possess of the efficacy of lightning rods, whether 
 they have met all the conditions required for perfect 
 security against discharges of atmospheric electricity, 
 without endangering the buildings to which they 
 are applied, and finally to inquire into the validity 
 of certain popular objections to their general employ 
 ment. 
 
 It may be perceived, that in all these researches 
 we have adhered carefully to the safe and beaten 
 path of inductive science : in no case has any ad- 
 
118 EFFICIENCY OF LIGHTNING RODS 
 
 vance unwarranted by facts been attempted. The 
 same caution will be observed in examining the 
 different views which have been entertained of the 
 efficacy and action of lightning rods. For, as it has 
 been beautifully remarked by Lord Bacon, the great 
 father of inductive science, "Man, who is the ser 
 vant and interpreter of nature, can act and under 
 stand no further, than he has either in operation or 
 in contemplation observed of the method and order 
 of nature." 
 
 Whether Lightning Rods and other Metallic Conductors 
 have effectually guarded Buildings, &c. against 
 Damage by Lightning. 
 
 The cases in which continuous metallic con 
 ductors have afforded complete protection from 
 lightning, are by no means few or inconclusive. 
 We shall proceed to detail some of the most remark 
 able of such instances. Between the years 1820 
 and 1830 several church towers in Devonshire were 
 struck by lightning: amongst these were Shaugh 
 church, on the southern border of Dartmoor; Al- 
 phington church, near Exeter; Maryborough and 
 Kingsbridge churches, on the southern coast ; and 
 Charles church, at Plymouth : of these, one only 
 was protected by a lightning rod, viz., the church 
 at Plymouth. Now it is an important fact, that 
 although the conductor was broken in pieces by the 
 shock, as already stated (p. 100), this was the only 
 
AND OTHER CONDUCTORS. 119 
 
 instance in which the church and tower escaped 
 damage. 
 
 The church of St. Michael at Charlestown, was 
 very frequently struck and damaged by lightning 
 previously to the year 1760, when a lightning rod 
 was applied to it. It has never suffered since.* 
 
 The Dutch church at New- York was struck by 
 lightning in the year 1750, and again in 1763. The 
 electrical discharge in each case passed over the 
 metallic connections between the hammer of the 
 bell and the works of the clock, as in the cases of 
 Brixton and St. Martin s churches, already men 
 tioned (p. 100) ; in both instances portions of these 
 connecting wires were melted, and the building was 
 damaged. 
 
 In 1765, an iron rod was applied from the stem 
 of the weathercock along the exterior of the build 
 ing, and continued to the ground. During this year 
 there again fell on it a heavy stroke of lightning : 
 the building, however, was riot in the least degree 
 damaged, nor was any effect observable on the wire 
 connecting the bell with the clock, f 
 
 The chapel of the chateau of the Count Orsini, 
 in the province of Carinthia in Hungary, being on 
 an elevated site, received such frequent damage 
 from lightning, that divine service was no longer 
 celebrated there. In the year 1730 a single dis 
 charge occurred, which at once laid the bell-tower 
 in ruins. In 1778 the building was again nearly 
 
 * Phil Trans., vol. Ixiv. p. 133. 
 + Animaire for 1838, p. 604. 
 
120 EFFICIENCY OF LIGHTNING RODS 
 
 demolished by a similar explosion, and was again 
 rebuilt. The great discovery of Franklin, however, 
 began now to be appreciated, and a pointed light 
 ning rod was applied to the tower. During the 
 next five years, it was only once assailed by light 
 ning, and then no damage ensued ; nor does the 
 building appear to have suffered since. * 
 
 The royal chateau at Turin was frequently 
 damaged by lightning up to the year 1772, when 
 Beccaria applied lightning rods to its principal roofs. 
 Since that time, although frequently menaced by 
 thunderstorms, it has remained uninjured. f 
 
 The fine tower of St. Mark, at Venice, more than 
 three hundred and forty feet high, was repeatedly 
 damaged by lightning, to which from its elevated 
 position, it was greatly exposed. This tower ter 
 minates in a pyramid eighty-seven feet high, on 
 which stands a wooden figure of an angel covered 
 with copper. The detached pieces of iron employed 
 in its construction produced (as at St. Bride s church 
 in London) (p. 86) very destructive effects. It was 
 damaged severely in 1388, at which time it was a 
 wooden structure. In 1417 it was set on fire by 
 lightning, and destroyed. In 1489 it was again 
 struck, and the pyramid reduced to ashes. It was 
 now rebuilt with stone. In the years 1548, 1565, 
 and 1653, it again suffered from the same cause, and 
 in 1745 a stroke of lightning fell on it with such 
 
 * ROZIER, xxiv. p. 323. 
 
 f Annuaire, p. 605 ; MAEBUCH, Enkyk. der Exp. Physik. vol. i. 
 p. 314. 
 
AND OTHER METALLIC CONDUCTORS. 121 
 
 tremendous force, that the whole tower was nearly 
 ruined: it was rent in no less than thirty-seven 
 places. The cost of repairs in this instance amounted 
 to eight thousand ducats. In the years 1761 and 
 1762 it was again severely damaged.* 
 
 We have here sufficient evidence of the frequent 
 effects of lightning on this building, whilst unpro 
 tected by a conductor. Now, in the year 1766, a 
 lightning rod was applied along the exterior of the 
 tower, reaching from the metallic figure on the top 
 of the pyramid to the ground. Since this period we 
 find no further account of its having suffered in the 
 least degree from the effects of lightning. 
 
 We have already noticed the application of a 
 lightning rod to the beautiful tower of the cathedral 
 at Sienna (p. 92), which, although frequently struck 
 and damaged by lightning before the application of 
 the rod, has not since experienced any ill conse 
 quences, although struck by lightning in a similar 
 way. 
 
 In EOZIER S Journal, vol. xxii., we find an inter 
 esting and circumstantial account of a powder maga 
 zine at Glogau in Silesia, struck by lightning in 
 May, 1782, and defended by a pointed lightning 
 rod. " The flash was seen to leave the cloud and 
 strike upon the rod; it appeared to envelope the 
 whole building in electrical fire. The sentinel on 
 guard lost his senses for some minutes, but no dam- 
 
 * Extract from registers of the city; ARAGO, Annuaire pour 
 1838. 
 
 6 
 
122 > EFFICIENCY OF LIGHTNING RODS 
 
 age ensued." The conductor terminated in a well 
 of water. 
 
 It may be well to contrast this result with the 
 results in other cases, in which discharges of light 
 ning have fallen in a similar way on magazines of 
 gunpowder, not provided with lightning rods. 
 
 In March, 1782, about the same period, a dis 
 charge of lightning fell on a magazine at Fort 
 Marlborough, in Sumatra, not having a lightning 
 rod, and set fire to four hundred barrels of gun 
 powder.* 
 
 The magazine in the vaults of the church of St. 
 Nazaire at Brescia, a large dpot of gunpowder be 
 longing to the republic of Venice, shared a similar 
 fate, in August, 1769. The electrical discharge 
 struck the tower, and descending to the vaults, ex 
 ploded above 207,600 pounds of gunpowder, f By 
 this dreadful catastrophe above three thousand per 
 sons perished, and nearly one-sixth of the beautiful 
 city of Brescia was destroyed. 
 
 A similar accident occurred to a magazine at 
 Malaga, in August, 1780, and at Tangiers, in May, 
 1785. At Luxembourg, in June, 1807, a magazine 
 of gunpowder, built in former times by the Spaniards 
 on a solid rock, was struck by lightning and blown 
 up : more than 28,000 pounds, or about twelve tons 
 of gunpowder, were fired, by which the lower part 
 of the town was laid in ruins.:): 
 
 * MAKSDEN S History of Sumatra, third edition, p. 19. 
 
 f ARAGO, Annuaire, 1838, p. 483. \ Idem. 
 
AND OTHER METALLIC CONDUCTORS. 123 
 
 In September, 1808, a magazine near Venice 
 was exploded by lightning, and in November, 1829, 
 another at Navarino."* In the East Indies there 
 have been very lately two explosions of this kind, 
 viz., a magazine at Dum Dam, and a coming-house 
 at Mazagon : both these establishments were unpro 
 vided with lightning rods. 
 
 Now it is to be observed, on the contrary, that 
 although such rods have been employed for the de 
 fence of these buildings from lightning for more than 
 seventy years, yet in no instance in which a light 
 ning rod has been applied, has any explosion hap 
 pened. 
 
 The protecting effect of a lightning conductor 
 was well shown at Philadelphia, "United States, in 
 July, 1770 : a severe thunderstorm overspread the 
 city, and produced electrical discharges in four 
 places, so that three houses and a merchant ship in 
 the river were struck by violent detonations. One 
 of the houses had a pointed lightning rod, and 
 escaped damage : the other houses, on the contrary, 
 together with the merchant ship, suffered considera 
 bly. On examining the point of the conductor on 
 which the lightning fell, it was found to have been 
 melted.f 
 
 The old church of St. Paul s, in London, not 
 having been provided with a lightning rod, was 
 twice struck by lightning and damaged. The pre- 
 
 * Report by Admiral Rosamel to the Minister of Marine, No 
 vember, 1829. t -Annuaire, p. 609. 
 
124 EFFICIENCY OF LIGHTNING RODS 
 
 sent still more elevated building having lightning 
 conductors of great magnitude, has never suffered 
 from this source of danger. * 
 
 In addition to these instances of the operation 
 of pointed metallic rods, in defending buildings 
 against damage by lightning, it may be observed, 
 that edifices furnished with continuous metallic 
 masses, either with a view to utility or ornament, 
 have seldom if ever suffered from* atmospheric elec 
 tricity. 
 
 The learned orientalist, Michaelis, states, that the 
 temple of Jerusalem had not, during ten centuries, 
 experienced a single condensed electrical explosion. 
 Now, in examining the accounts given of this build 
 ing, it appears to have been covered inside and out 
 with burnished plates of metal, Josephus says gold. 
 The top was covered with a thick gilding, and 
 bristled with long pointed iron or steel pikes. The 
 object of this appears to have been to prevent birds 
 from settling on the gilded dome. Under the court 
 of the temple were cisterns, which received the rain 
 from the roof through metallic pipes. A more com 
 plete system of efficient conductors of lightning 
 could not have been devised. The conditions we 
 have insisted on (p. 90), viz., that of bringing the 
 building as nearly as possible into the same electrical 
 position that it would be in, were it a complete 
 metallic mass, are here fully satisfied, and we ac 
 cordingly find, that this building never sustained 
 
 * Phil. Trans. 
 
AND OTHER METALLIC CONDUCTORS. 125 
 
 the slightest damage from lightning, although from 
 its elevated position it was exposed to the frequent 
 and terrible storms of Palestine. It is more than 
 probable, from the circumstance of the roof having 
 been covered with cedar, both within and without, 
 that a heavy stroke of lightning falling on it, would, 
 but for the metallic coatings, have set it on fire. 
 When we consider (as observed by Arago), how 
 carefully the ancients recorded instances of damage 
 done to their buildings by lightning, it is impossible 
 to explain the silence of historians on this point, ex 
 cept by admitting that the Jewish temple had never 
 suffered in thunderstorms. 
 
 A parallel instance is found in the case of the 
 cathedral at Geneva. This building, the most promi 
 nent and elevated in the whole city, has for more 
 than two centuries enjoyed a perfect immunity from 
 the effects of lightning, whilst the bell-tower of St. 
 Gervais, situated much lower than the cathedral, has 
 been frequently struck and damaged. 
 
 In the year 1771, Saussure investigated the cause 
 of this, and on examination found, that the great 
 central tower of the cathedral, built of wood, and 
 which had existed above three hundred }^ears, was 
 completely covered from its summit with tinned iron 
 plate : this communicated at the base of the tower 
 with the various metallic masses about the roofs, and 
 lastly by metallic pipes with the ground, thus form 
 ing an extensive and complete series of conduc 
 tors, equivalent to the transmission of the most 
 powerful electrical discharges. 
 
126 EFFICIENCY OF LIGHTNING RODS 
 
 The Monument near London Bridge, which by 
 its construction has an uninterrupted series of con 
 ductors reaching through its interior, from the urn 
 on its summit to the earth, is another instance. This 
 building has remained safe amidst the many furious 
 thunderstorms which have, since its erection in 1677, 
 frequently spread over the metropolis, and damaged 
 some of its principal edifices. 
 
 It may be observed as a general truth, that build 
 ings in any way cased or supplied with metallic sub 
 stances continued to the ground, invariably escape 
 damage from lightning ; and that where such metal 
 lic coverings or connections are only partially applied, 
 the damage commences where they cease, and on the 
 contrary, ceases where they commence. Thus one 
 of the large granite chimneys, above a hundred feet 
 high, at the Koyal Victualling Yard, near Plymouth, 
 was, on the 25th of May, 1841, rent by lightning 
 sixty feet down, as far as the copper roofing of the 
 building in connection with it : here all damage 
 ceased, the copper having free conducting commu 
 nication with the earth by the metallic pipes for 
 carrying off the rain. 
 
 The effects of lightning on St. Peter s church in 
 London, in the summer of the year 1774, are most 
 remarkably conclusive on this point. The spire of 
 this church was surmounted by a large key of gilded 
 copper, and was covered with lead as far as the brick 
 tower; accordingly so far no damage ensued, but 
 between this and the leaded roof of the church the 
 tower was much rent. At the roof, the metallic con- 
 
AND OTHER METALLIC CONDUCTORS. 127 
 
 duction again commenced, and continued to the 
 ground ; and here again the damage ceased.* 
 
 Such are some of the most striking facts bearing 
 on the protective operation of lightning rods on 
 buildings : we will now proceed to examine their 
 influence on shipping. 
 
 In the year 1839 the Lords Commissioners of the 
 Admiralty appointed a naval commission to inves 
 tigate the best method of applying lightning con 
 ductors to Her Majesty s ships. After a very elabo 
 rate inquiry, they drew up a report on this important 
 question, extending to more than eighty folio pages, 
 and containing a valuable mass of oral and docu 
 mentary evidence, received from naval officers, men 
 of science, and other competent persons. This re 
 port was laid on the table of the House of Commons, 
 and in February 1840 was ordered to be printed. 
 One of the points to which the commission directed 
 its attention was this : " Whether in a case in which 
 ships not having lightning conductors have been 
 struck by lightning, it appears that other ships in 
 company having lightning conductors, have either 
 not been struck, or have escaped injury." The fol 
 lowing are some of the cases which were brought 
 under the notice of the Commissioners : 
 
 In 1815 His Majesty s ship Norge, was severely 
 damaged by lightning, whilst the Warrior, of sev 
 enty-four guns, with a pointed conductor, lying close 
 to the Norge, received no injury. The electrical ac- 
 
 * Phil. Trans., voL Ixiv, p. 133. 
 
128 EFFICIENCY OF LIGHTNING RODS, 
 
 tion in this case illuminated the linked portions of 
 the conductor, and appeared to stream down into the 
 sea. There were many other ships in the harbor, 
 but none received any damage except one, and this 
 ship was the only one which had no conductor. 
 
 In February, 1824, His Majesty s ship Milford, 
 not having a lightning conductor, was struck by 
 lightning in the Harnoaze, Devonport, and damaged, 
 whilst His Majesty s ship Caledonia, of one hundred 
 and twenty guns, about eighty fathoms distant, hav 
 ing pointed conductors, escaped. 
 
 In September, 1824, His Majesty s ships Phaeton 
 and Adventure were lying at Gibraltar Mole : the 
 Phaeton had not conductors, but the Adventure had : 
 the ships were within a cable s length of each other. 
 Under these circumstances the Phaeton was struck 
 and damaged by lightning ; the Adventure escaped. 
 
 In January, 1830, His Majesty s ships Madagas 
 car ^ jEtna, and Mosquito, were about to come to an 
 anchor off Corfu. A violent thunderstorm arose, 
 which struck and severely damaged the Madagascar 
 and Mosquito, the ships without conductors : the 
 jEina, which had a conductor at the main, although 
 struck by lightning repeatedly on this mast, escaped. 
 
 In 1837, the Cochin tank- vessel, in Trincomalee 
 harbor, had her foremast shivered by lightning, 
 whilst Her Majesty s ship Winchester, about two 
 cables, length distant, escaped. The Winchester had 
 a conductor, and the lightning was observed to 
 stream down it; the tank- vessel, on the contrary, 
 was undefended. 
 
AND OTHER METALLIC CONDUCTORS. 129 
 
 In November, 1837, the Pelican, of sixteen guns, 
 without a conductor, was struck by lightning on the 
 coast of Africa, and damaged; the Waterwitch, an 
 other of Her Majesty s ships, at anchor within a short 
 distance, escaped. 
 
 In March, 1838, Her Majesty s ship Ceylon, in 
 Malta harbor, was struck by lightning, which shiv 
 ered the foremast ; she had no conductor. Her Ma 
 jesty s ships Talavera and Bellerophon, both fur 
 nished with lightning conductors, escaped, as did the 
 sheers for masting ships, which were similarly armed. 
 This instance is the more remarkable, from the fact 
 that the Ceylon, as a receiving ship, had only a short 
 pole above her foremast, whereas the other ships, 
 being fully rigged, their masts extended above one 
 hundred and fifty feet into the air. 
 
 " In addition to these instances," say the Com 
 missioners, " we beg to call their Lordships atten 
 tion to the case of the New- York packet, laid before 
 the Lord High Admiral in 1827, by the Navy Board. 
 It appears that on her passage to Liverpool, in 1827, 
 this ship was struck by lightning, and sustained con 
 siderable injury. The conductor was not up at the 
 time; but the weather continuing stormy, it was 
 got out, and triced up to the mast-head. The ship 
 was a second time struck by a most severe stroke 
 of electricity, which fused the chain, and passed 
 into the water without doing further damage." 
 (pp. 52, 105.) 
 
 The following are some additional cases con 
 clusive of the efficacy of lightning rods as a defence 
 
130 EFFICIENCY OF LIGHTNING RODS, 
 
 against lightning, the ships having been fitted with 
 pointed conductors fixed in all their masts : 
 
 His Majesty s frigate Dryad was struck by light 
 ning in a tornado on the coast of Africa, in 1830. 
 Commander Turner says, " that the discharge fell on 
 both the fore and mainmasts with a loud whizzing 
 sound ; the thunder was nearly simultaneous with the 
 lightning, and the ship appeared enveloped in flames." 
 
 His Majesty s frigate Druid, at Eio Janeiro, in 
 1832, encountered awful lightning, which was "con 
 ducted safely down the conductors on the fore and 
 mainmasts." * 
 
 His Majesty s ship Asia, in the Tagus, in 1831, was 
 assailed by lightning during a squall, with heavy 
 rain ; the electrical explosion passed off safely upon 
 the conductor on the mainmast.f 
 
 Her Majesty s frigate Talbot, in July, 1842, was 
 struck by lightning soon after getting under weigh 
 at Sheerness. The lightning was observed to fall 
 immediately on the conductor when the cloud burst 
 over the mainmast head.;): 
 
 The cases of the Beagle and Actceon, referred to 
 in our second section each receiving heavy electri 
 cal charges upon their conductors, without harm 
 furnish very complete and important evidence of the 
 beneficial operation of pointed conductors. 
 
 Lieutenant Sulivan, who had witnessed the effects 
 of lightning in shattering the mast of His Majesty s 
 
 * Report of Commission, p. 94. 
 
 | Witnessed by Mr. Sadler, the master of the ship. 
 
 \ Reported to the Lords of the Admiralty. 
 
AND OTHER METALLIC CONDUCTORS. 131 
 
 ship Thetis, happened to be on duty at the time the 
 electrical discharge fell on the Beagle; he states 
 that, "when the clouds by which the ship was 
 enveloped burst on the mast, the mast and ship ap 
 peared to be wrapped in a blaze of fire ; the vessel 
 trembled under the crash of the thunder, and a 
 vibratory whizzing sound was heard along the con 
 ductors." 
 
 Lieutenant Bonham, and Mr. May, the carpenter, 
 who were both on deck when the Actceon was as 
 sailed by lightning, describe very similar effects. 
 The discharges occurred within a fearfully short 
 distance of the ship, and the flashes were so vivid, 
 that the observers were for a time deprived of 
 sight. When the ship was struck, the lightning 
 was observed to fall immediately on the conductor ; 
 the crash of the thunder was intense and simultane 
 ous with the lightning. The cutlasses stowed around 
 the mast rattled in their stand, and there was a loud 
 whizzing sound upon the conductor, which appeared 
 enveloped in electrical fire."* 
 
 These cases, which have much in common, are 
 characterized by well-known phenomena of electri 
 cal action; they have occurred in various parts of 
 the world, at different times, and have been reported 
 on by persons in no way interested in perverting the 
 facts ; hence, no doubt can remain as to the decisive 
 evidence they afford, of the protecting power of 
 pointed conductors. 
 
 * Account by the master. 
 
132 WHETHER LIGHTNING RODS 
 
 Whether Lightning Rods attract Lightning. 
 
 Amongst the objections made to the employment 
 of lightning rods, there appears to have been none 
 so popular, and at the same time so plausible, as this, 
 viz., that by setting up pointed conductors, we invite 
 lightning to our buildings, which otherwise would 
 not fall on them ; that should the quantity of elec 
 tricity discharged be greater than the rod can carry 
 off, the redundant quantity must necessarily act 
 with destructive violence ; and that since we can 
 never know the quantity of electricity which may 
 be accumulated in, and be discharged from, the 
 clouds, it is not improbable but that any conductor 
 which we can conveniently apply, may be too small 
 for the safe conveyance of such a charge. 
 
 Although the advocates of these opinions have 
 never adduced any substantial fact, or any known 
 law of electricity, in support of them ; although they 
 have never, by any appeal to experience, shown that 
 buildings armed with lightning rods have been 
 struck by lightning more frequently than buildings 
 not so armed, nor demonstrated any single instance 
 in which an efficient lightning rod, properly ap 
 plied, has failed to afford protection, nevertheless 
 such views have been commonly entertained : in 
 deed so strenuously have they been insisted on, 
 and that, too, by persons of education and influence, 
 that the Governor-general and Council of the Honor 
 able the East India Company were led to order the 
 lightning rods to be removed from their powder- 
 
ATTRACT LIGHTNING. 133 
 
 magazines and other public buildings, having in the 
 year 1838 come to the conclusion, from certain 
 representations of their scientific officers, that light 
 ning rods were attended by more danger than ad 
 vantage ; in the teeth of which conclusion, a maga 
 zine at Dum Bum, and a coming-house at Mazagon, 
 not having lightning rods, were struck by lightning 
 and blown up.* 
 
 In a work on Canada, published so lately as the 
 year 1829, f we find the following passage : " Science 
 has every cause to dread the thunder rods of 
 Franklin: they attract destruction, and houses are 
 safer without than with them. "Were they able to 
 carry off the fluid they have the means of attracting, 
 then there could be no danger, but this they are by 
 no means able to do." Assertions such as these, 
 appealing as they do to the fears of mankind, rather 
 than to their dispassionate and sober judgment, have 
 not altogether failed in obtaining that sort of tem 
 porary favour which so frequently attends a popular 
 prejudice, promulgated without reason, and received 
 without proof. Not only is the idea that a lightning 
 rod invites lightning unsupported by any fact, but 
 it is absolutely at variance with the whole course of 
 experience. 
 
 The notion that a lightning rod is a positive 
 evil, appears to have arisen entirely out of assump- 
 
 * Correspondence with the Honorable Board of Directors ; Pro 
 fessor Daniell and Dr. O Shaughnessy. 
 
 f Three Years in Canada. By F. McTaggart, Civil Engineer in 
 the service of the British Government. 
 
134 WHETHER LIGHTNING RODS 
 
 tions, and a partial consideration of facts. Thus in 
 consequence of the track of a discharge of lightning 
 being always determined through a certain line or 
 lines, which upon the whole least resist its progress, 
 it has often been found to fall in the direction 
 of pointed metallic bodies, such as vanes, vane- 
 spindles, iron bars, knives, &c. The instances in 
 which these bodies seem to have determined the 
 course of lightning have been carefully recorded, 
 the phenomena being peculiarly striking and re 
 markable (p. 86) ; but on the other hand, no atten 
 tion has been given to those instances in which 
 lightning has altogether avoided such bodies, and 
 passed in other directions, (p. 72.) Now it will 
 be found, as we shall presently show, that the action 
 of a pointed conductor is purely passive. It is 
 rather the patient than the agent ; and such con 
 ductors can no more be said to attract or invite a 
 discharge of lightning, than a watercourse can be 
 said to attract the water which flows through it at 
 the time of heavy rain. 
 
 We have shown in a former section (p. 106), what 
 quantity of metal is really sufficient for the perfect 
 conduction of any quantity of lightning liable to be 
 discharged in the most severe thunderstorms: there 
 fore, to assume that any conductor which may be 
 applied is not sufficiently capacious, is to reason 
 against experience, and to resort to a species of 
 argument quite foreign to the conditions of the case. 
 It would be, as if we were to insist upon the danger of 
 applying water pipes to buildings, under the assurnp- 
 
ATTRACT LIGHTNING. 135 
 
 tion that we do not really know what quantity of 
 rain may possibly fall from the clouds, and that 
 hence the pipe may after all be too small to con 
 vey it. 
 
 In all these reasonings we should recollect, as 
 already explained (p. 12), that the forces in operation 
 are distributed over a great extent of surface, and 
 that the point or points upon which lightning strikes, 
 is dependent on some peculiar condition of the in 
 tervening air, and the amount of force in operation, 
 not on the mere presence of a metallic body pro 
 jecting for a comparatively short distance into the 
 atmosphere, " that such bodies provoke the shaft 
 of heaven is the suggestion of superstition, rather 
 than of science."* 
 
 We shall now leave the theoretical discussion of 
 this question, and direct attention to the facts them 
 selves, and examine how far the evidence deducible 
 from such facts is conclusive upon this important 
 point. 
 
 During the thunderstorm which spread over the 
 neighborhood of Plymouth, in May, 1841, the elec 
 trical discharge struck one of the high chimneys at 
 the Victualling- Yard, as already mentioned (p. 126) ; 
 it fell also on the topmast of the sheer-hulk off the 
 Dock- Yard, about a mile and a half distant. Now 
 the circumstances attendant on these discharges of 
 lightning bear directly on the question before us. 
 The chimney at the Victualling- Yard is a round 
 
 * LESLIE, Edin. Phil. Magazine. 
 
136 WHETHER LIGHTNING RODS 
 
 column of granite, about one hundred and twenty 
 feet high, attached to the bakehouse ; it has not a 
 particle of metal in its construction, nor has it any 
 projecting point It stands at a distance of about one 
 hundred yards from a clock- tower in the same yard ; 
 which, on the contrary, has not only a metal vane, 
 and cross-pieces of metal, indicating the four cardinal 
 points, but its dome is covered with copper, and 
 there is a large conductor continued partly within 
 and partly without the tower, from the dome to the 
 ground. In the sheer-hulk a very small metallic 
 wire was led along the pole topmast, and connected 
 with the large metallic chains attached to the mast 
 and sheers: the height of this pole was compara 
 tively low, and it was completely overtopped by 
 the neighbouring spars of the line-of-battle ship 
 Cbrnwallis, fully rigged, and fitted with conductors 
 on each of her masts. Now when the disruptive 
 discharges took place, they fell on the granite 
 tower, which had not a single metallic substance in 
 its construction, and on the low flagstaff pole of 
 the sheer-hulk s mast, notwithstanding that the clock- 
 tower near the chimney offered every possible "in 
 vitation to the discharge, and the great altitude of 
 the line-of-battle ship s spars were in the most favor 
 able position for " attracting" the electrical explo 
 sion. The chimney was rent for sixty feet ; the 
 flagstaff of the hulk s mast was slightly injured, and 
 the small wire broken and fused ; the lower mast 
 and chains were uninjured. 
 
 On the 25th of March, 1840, Her Majesty s ships 
 
ATTRACT LIGHTNING. 137 
 
 Powerful and Asia, each of eighty -four guns, were 
 anchor within a short distance of each other in 
 Yourla Bay, in the Mediterranean. The Asia had 
 the fixed pointed conductors attached to each of her 
 masts ; the Powerful was unprovided with any light 
 ning conductor whatever. Under these conditions 
 they were both exposed to a severe thunderstorm. A 
 discharge of lightning fell on the Powerful, the ship 
 without conductors, and shivered some of her spars ; 
 whilst the Asia, where every supposed " invitation " 
 to the discharge was most prominent, experienced no 
 ill effect. 
 
 If no other cases were on record, these alone, 
 would be sufficient to dispel all apprehensions of a 
 metallic conductor " attracting or inviting " lightning. 
 A great number of instances, however, equally clear 
 and satisfactory, exist ; from these we have selected 
 the following : 
 
 Amongst some interesting remarks on the effects 
 of lightning, by Professor Winthrop, communicated 
 by Dr. Franklin to Mr. Henley, it is stated, that a 
 tree which stood at the distance of fifty-two feet only 
 from a pointed conductor attached to a house, was 
 struck by lightning and shivered, while the conduc 
 tor and house escaped,* that is to say, the lightning 
 fell on a body, which, according to the prevalent 
 notion, had little or no attraction for it, and held out 
 no " invitation," in preference to one which did, a 
 fact totally at variance with the whole assumption. 
 
 * Phil Trans, vol. Ixiv., p. 152. 
 
138 WHETHER LIGHTNING RODS 
 
 We have already adverted to the case of the 
 Southampton (p. 72), in which a heavy electrical dis 
 charge fell upon the sea close to the ship, during a 
 thunderstom on the east coast of Africa. But what 
 makes this case especially applicable to the question 
 now under consideration, is the circumstance, that 
 all her masts were fitted with fixed lightning con 
 ductors, which terminated in copper spikes. The 
 storm was awful, and it is stated by Mr. Martin, the 
 master, to have lasted from ten P.M. to two A.M. 
 " The night was pitchy dark, from the density of the 
 surrounding clouds : the roar of the thunder was inces 
 sant, and the flashes of lightning frequently so vivid, 
 as to affect the sight for some minutes," yet no ill 
 effect was experienced ; the electrical discharge was 
 not drawn down in an explosive form exclusively 
 upon the conductors, although it actually fell with 
 violence upon the sea close to the vessel. 
 
 Similar effects were observed in His Majesty s 
 ship Sapphire, armed with pointed conductors of the 
 same kind. Captain "Wellesley, who commanded 
 this ship, states that "the lightning was so vivid, and 
 the flashes so quick in succession all around the ship, 
 that although the duty to be done was important, I 
 hesitated to expose the crew to them ;* yet the ship 
 was not struck." In another place he states, "that 
 the Sapphire often met with very severe lightning, 
 but it was never attracted to her."f 
 
 The frequent instances in which lightning avoids 
 
 *They were afraid to hoist the boats out. 
 
 \ Report of Commission on Shipwreck by Lightning. 
 
ATTRACT LIGHTNING. 139 
 
 the most prominent parts of of buildings, and falls 
 obliquely upon some point far removed from them, 
 may be further adduced as evidence against the at 
 tractive influence of such projections. The long zig 
 zag track of lightning, arising from the resistance of 
 the air to its more direct path, may cause it to fall 
 very obliquely on the earth s surface, as is well 
 known : indeed some of the directions of the zig 
 zag, may become almost horizontal. Now, in these 
 cases, the pointed extremities of a tower, or the 
 masts of ships, have no influence whatever on the 
 course of the explosion ; which, on the principles 
 already explained (p. 70), finds its way through the 
 least resisting interval. Mr. Alexander Small states, 
 in a letter to Dr. Franklin, that he saw an explosion 
 of lightning pass before his window in a direction 
 nearly horizontal, and strike a clock-tower far be 
 neath its summit. 
 
 In the discharge of lightning, which fell on His 
 Majesty s ship Opossum in the English Channel in 
 March, 1825, "a peal of thunder burst on the main 
 rigging, and split the topmast cap."* Her Majesty s 
 ship Pique was struck by lightning in the St. Law 
 rence, in November, 1839, by a discharge which fell 
 on the foremast just beneath the head of it, and 
 from thence passing down the mast, did considerable 
 damage. Such cases, although comparatively rare, 
 and to a certain extent exceptions to the general 
 course of lightning, are still sufficient to show how 
 
 * Ship s log. 
 
140 WHETHER LIGHTNING RODS 
 
 little the direction of electrical explosions is deter 
 mined by the influence of points considered as mere 
 attmctors, and that it is only when they can contrib 
 ute to the equalization of the opposite electrical 
 forces, that lightning strikes on them. Franklin, in 
 endeavoring to draw off the electricity of a charged 
 sphere by means of a pointed wire, found that the 
 point when placed on a rod of glass or wax, had no 
 action on it.* 
 
 When this large mass of evidence is duly con 
 sidered, together with the fact, that lightning strikes 
 indiscriminately, trees, rocks, and buildings, and even 
 the ground near them, we are compelled to admit 
 that properly constructed lightning rods are perfectly 
 precise in their operation, and that the common 
 notion that they "invite destruction" to our build 
 ings, is not warranted by any sound argument drawn 
 from experience. 
 
 It may not be unimportant to notice here the 
 following extract from the Memoirs of the Count de 
 Forbin, already alluded to. (p. 21.) In describing the 
 large St. Helmo s fires, observed in the vane of the 
 mainmast, he says, " I ordered one of the sailors to 
 take it (the vane) down ; but scarcely had he taken 
 the vane from its place, when the fire fixed itself on 
 the head of the mainmast, from which it was impos 
 sible to remove it ;"f so that the presence of the 
 metallic point was not at all necessary to the elec 
 trical discharge. 
 
 * FRANKLIN S Letters, p. 56. 
 
 f Letters on Electricity. By the Abbd Nollet. Vide Phil. 
 Trans, for 1753, p. 201. 
 
ATTRACT LIGHTNING. 141 
 
 Before quitting the subject of the absolute pro 
 tection from lightning afforded by conductors, the 
 Naval Commission inquire, whether, according to 
 the common prejudice, conductors have the power 
 of attracting a flash of lightning, which in their 
 absence would not have occurred ; and their report 
 states " that the instances of accidents to ships 
 without conductors, and the comparatively rare occur 
 rence of lightning being observed to strike on a 
 conductor, would tend to negative such a supposi 
 tion."* They further consider, from the instances 
 which were submitted to them, of ships without 
 conductors having been struck with lightning, in the 
 presence of ships furnished with them, which were 
 not so struck, that most complete evidence is 
 afforded " either of the little influence exerted by 
 such conductors in inducing or attracting an ex 
 plosive discharge, or of their efficacy in harmlessly 
 and imperceptibly conveying away electricity to the 
 water."f 
 
 Whether in certain cases pointed Conductors actually 
 prevent Explosions of Lightning from falling on 
 Buildings. The Phenomena observed when a con 
 centrated Discharge strikes upon a Conductor. 
 
 Coulomb proved by actual experiment, that the 
 depth of the electric fluid on a conductor, always 
 increases in a rapid proportion in approaching the 
 
 * Report of Commission, p. 4. f 
 
142 DO POINTED CONDUCTORS AVERT 
 
 edges ; and that the effect is still more augmented at 
 corners, which may be regarded as two edges com 
 bined. The effect is still farther increased if any 
 part of a conductor have the form of a point. Now 
 the pressure of the air is probably the only force 
 which retains the electric fluid on a conductor ; and 
 it is evident that if at the edges, corners, of angular 
 points of a conductor, the electric depth be so much 
 increased that the force of the electric fluid shall 
 exceed the restraining pressure of the atmosphere, 
 the electricity must escape. Accordingly, it is found 
 practically impossible to accumulate any quantity of 
 electricity on a conductor furnished with points.* 
 
 To discharge a Leyden phial silently. When a 
 large jar is fully charged, which would give a vio 
 lent shock, put one of your hands in contact with 
 its outside coating, and with the other hand hold a 
 sharp-pointed needle; and keeping the -point di 
 rected towards the knob of the jar, proceed gradually 
 towards it, until the point of the needle touches the 
 knob. This operation discharges the jar com 
 pletely, and the operator will either receive no 
 shock at all, or so small a one as can hardly \>G 
 perceived. The point of the needle, therefore, has 
 silently and gradually drawn all the charge from the 
 inside of the Leyden phial. 
 
 If this experiment be performed in the dark, 
 the point of the needle will appear illuminated in 
 its way toward the knob of the phial, which is 
 another proof of its drawing off the charge, f 
 
 * Noad s Electricity, p. 18. f Rees Encijc. vol. 13. 
 
EXPLOSIONS OF LIGHTNING^ 
 
 143 
 
 The Electrified Cotton. Take a small lock of cot 
 ton (c), extend it in every direction as much as may 
 be practicable, and by means of a linen thread about 
 
 FIG. 14. 
 
 five or six inches long, or by a thread drawn out of the 
 same cotton, tie it to the end of the prime con 
 ductor P; under this, attach in a similar way an 
 other lock (6), and to this a third lock (a) ; and 
 then let the electrical machine be put in action, and 
 the locks of cotton on being electrified, will imme 
 diately swell out, by repelling their filaments from 
 each other, and will stretch themselves towards the 
 nearest conductor. In this situation, the machine 
 continuing in action, present the end of a finger or 
 the knob of a wire, toward the lower lock of cotton, 
 and this will then immediately move towards the 
 
144 DO POINTED CONDUCTORS AVERT 
 
 finger, or the point N, endeavoring to touch it, 
 much in the same way that the petty fragments on 
 the lower surface of a thundercloud lean toward the 
 earth. On presenting a needle at N. to the lowest 
 lock, a, it immediately shrunk back upon the lock 
 b, and this again upon c, and all together upon the 
 conductor p, where the locks remained as long as 
 the needle continued under them. Remove the 
 needle, and the cotton will come again toward the 
 finger. Present the needle, and the cotton will 
 shrink again ; which clearly shows that the needle, 
 being sharp-pointed, draws off the electric fluid from 
 from, the cotton, and puts it in a state of being at 
 tracted by the prime conductor ; which effort can 
 not be produced by a wire having a blunted end, or 
 a round ball for its termination. 
 
 Dr. Franklin observes, "that electricity is not 
 more disposed to leave, or more easily drawn off 
 from any one part of an electrified sphere than from 
 another. But that is not true of any other figure. 
 From a cube it is more easily drawn at the corners 
 than at the plane side, and so from the angles of a 
 body of any other form, and still more easily from 
 the angle that is the most acute. For the reasons, 
 why electrified bodies discharge their electricity upon 
 unelectrified bodies more easily, and at a greater dis 
 tance from their angles and points than from their 
 smooth sides, may not be easily determined. Differ 
 ent philosophers have advanced different theories ; 
 but of the nature of points all are agreed. 
 
 " Those points will also discharge into the air, 
 
EXPLOSIONS OF LIGHTNING? 145 
 
 when the body is overcharged, without bringing any 
 non-electric near to receive what is thrown off. For 
 the air, though an electric per se, yet has always more 
 or less water and other non-electric matters mixed 
 with it ; and these attract and receive what is so dis 
 charged. 
 
 "But points have a property, by which they 
 draw on as well as throw off the electric fluid at 
 greater distances than blunt bodies can. That is, as 
 the pointed part of an electrified body will discharge 
 the electricity of that body, or communicate it 
 farthest to another body, so the point of an unelectri- 
 fied body will draw off the electrical fluid from an 
 electrified body, farther than a blunter part of the 
 same unelectrified body will do. Thus a pin held 
 by the head, and the point presented to an electrified 
 body, will draw off its electricity at a foot distance ; 
 when, if the head were presented instead of the point, 
 no such effect would follow. To understand this, we 
 may consider, that if a person standing on the floor 
 would draw off the electrical fluid from an electrified 
 body, an iron crow and a blunt knitting-needle held 
 alternately in his hand, and presented for that pur 
 pose, do not draw with different forces in proportion 
 to their different masses. For the man, and what he 
 holds in his hand, be it large or small, are connected 
 with the common mass of unelectrified matter ; and 
 the force with which he draws is the same in both 
 cases, it consisting in the different proportion of elec 
 tricity in the electrified body and that common mass. 
 But the force with which the electrified body retains 
 7 
 
146 DO POINTED CONDUCTORS AVERT 
 
 its electricity by attracting it, is proportioned to the 
 surface over which the particles are placed ; i. e. four 
 square inches of that surface retain their electricity 
 with four times the force that one square inch retains 
 its electricity. And as in plucking the hairs from the 
 horse s tail, a degree of strength not sufficient to pull 
 away a handful at once, could yet easily strip hair 
 by hair ; so a blunt body presented cannot draw off 
 a number of particles at once ; but a pointed one, 
 with no greater force, takes them away easily, parti 
 cle by particle. 
 
 " These explanations of the power and operation 
 of points, when they first occurred to me, and while 
 they first floated in my mind, appeared perfectly 
 satisfactory ; but now I have wrote them, and con 
 sidered them more closely in black and white, I must 
 own I have some doubts about them ; yet, as I have 
 at present nothing better to offer in their stead, I do 
 not cross them out: for even a bad solution read, 
 and its faults discovered, has often given rise to a 
 good one, in the mind of an ingenious reader. 
 
 " Nor is it of much importance to us to know the 
 manner in which nature executes her laws; tis 
 enough if we know the laws themselves. Tis of 
 real use to know that china left in the air unsup 
 ported will fall and break ; but how it comes to fall, 
 and why it breaks, are matters of speculation. Tis 
 a pleasure indeed to know them, but we can preserve 
 our china without it. 
 
 " Thus in the present case, to know this power of 
 points may possibly be of some use to mankind, 
 
EXPLOSIONS OF LIGHTNING? 147 
 
 though we should never be able to explain it. The 
 following experiments, as well as those in my first 
 paper, show this power. I have a large prime con 
 ductor, made of several thin sheets of clothier s paste 
 board, formed into a tube, near ten feet long and a foot 
 diameter. It is covered with Dutch embossed paper, 
 almost totally gilt. This large metallic surface sup 
 ports a much greater electrical atmosphere than a 
 rod of iron of fifty times the weight would do. It 
 is suspended by silk lines, and when charged, will 
 strike at near two inches distance a pretty hard 
 stroke, so as to make one s knuckle ache. Let a per 
 son standing on the floor present the point of a 
 needle at twelve or more inches distance from it, and 
 while the needle is so presented, the conductor can 
 not be charged, the point drawing off the fire as 
 fast as it is thrown on by the electrical globe. Let 
 it be charged, and then present the point at the same 
 distance and it will suddenly be discharged. In the 
 dark you may see a light on the point when the ex 
 periment is made. And if the person holding the 
 point stands upon wax, he will be electrified by re 
 ceiving the fire at that distance. Attempt to draw 
 off the electricity with a blunt body, as a bolt of 
 iron round at the end and smooth (a silversmith s iron 
 punch, inch thick, is what I use), and you must bring 
 it within the distance of three inches before you can 
 do it, and then it is done with a stroke and crack. 
 As the pasteboard tube hangs loose on silk lines, 
 when you approach it with the punch iron, it like 
 wise will move towards the punch, being attracted 
 
148 DO POINTED CONDUCTORS AVERT 
 
 while it is charged ; but if, at the same instant, a 
 point be presented as before, it retires again, for the 
 point discharges it. Take a pair of large brass scales, 
 of two or more feet beam, the cords of the scales being 
 silk. Suspend the beam by a packthread from the 
 ceiling, so that the bottom of the scales may be about 
 a foot from the floor. The scales will move round 
 in a circle by the untwisting of the packthread. 
 Set the iron punch on the end upon the floor, in such 
 a place as that the scales may pass over it in making 
 their circle. Then electrify one scale, by applying 
 the wire of a charged phial to it. As they move 
 round you see the scale draw nearer to the floor, and 
 tip more when it comes over the punch ; and if that 
 be placed at a proper distance, the scale will snap 
 and discharge its fire into it. But if a needle be 
 stuck on the end of the punch, its point upwards, 
 the scale instead of drawing nigh to the punch and 
 snapping, discharges its fire silently through the point 
 and rises higher from the punch. Nay, even if the 
 needle be placed upon the floor near the punch, its 
 point upwards, the end of the punch, though so 
 much higher than the needle, will not attract the 
 scale and receive its fire, for the needle will get it and 
 convey it away, before it comes nigh enough for the 
 punch to act. And this is constantly observable in 
 these experiments, that the greater quantity of elec 
 tricity on the pasteboard tube, the farther it strikes 
 or discharges its fire, and the point likewise will draw 
 it off at a still greater distance. The same experi 
 ment slightly varied, is given by Mr. Harris : c p 5, 
 
EXPLOSIONS OF LIGHTNING? 
 
 149 
 
 Fig. 17, is a long bent arm of light brass wire bal 
 anced by means of central pointy on the charging- 
 rod of the jar J, and on which it has free motion in all 
 directions ; A is a light disc of gilded wood, resem 
 bling a common scale-pan, covered with a lock of fine 
 cotton wool, and suspended by conducting threads 
 
 FIG. 17. 
 
 from the arm c b p. A pointed body B is placed on 
 the same conducting base t t with the jar. If the 
 jar be now charged, the cotton in the scale- pan will 
 begin to extend its filaments, and the whole will be 
 attracted toward the table, much in the same way as 
 a cloud appears to be attracted toward the earth, 
 causing the bent arm c p b to assume an inclined 
 position. If the arm be now caused to move upon 
 its centre p, so as to allow the artificial cloud A to 
 approach the point B, the arm will gradually assume 
 its previous horizontal position, in consequence of 
 
150 DO POINTED CONDUCTORS AVERT 
 
 the influence of the point in neutralizing the oppo 
 site forces. As the artificial cloud continues to ap 
 proach the point, this action proceeds so rapidly, as 
 frequently to produce a whizzing sound, the bent 
 arm recovering at the same time its horizontal posi 
 tion ; the scale-pan A, so far from being attracted by 
 the point, actually recedes from it, and very faith 
 fully represents the kind of operation of pointed 
 bodies on charged clouds, viz., their power of dis 
 charging the electricity of the clouds without attract 
 ing them. 
 
 " When the distances and charge are nicely ad 
 justed, this experiment is very striking and satis 
 factory. 
 
 " Now if the fire of electricity and that of light 
 ning be the same, as I have endeavored to show at 
 large, in a former paper, this pasteboard tube and 
 these scales may represent electrified clouds. If a 
 tube of only ten feet long will strike and discharge 
 its fire on the punch at two or three inches distance, 
 an electrified cloud of perhaps 10,000 acres may 
 strike and discharge on the earth at a proportionably 
 greater distance. The horizontal motion of the scales 
 over the floor, may represent the motion of the clouds 
 over the earth ; and the erect iron punch, a hill or high 
 building ; and then we have electrified clouds passing 
 over hills or high buildings at too great a height to 
 strike, which may be attracted lower till within their 
 striking distance. And lastly, if a needle fixed on the 
 punch with its point upright, or even on the floor 
 below the punch, will draw the fire from the scale 
 
EXPLOSIONS OF LIGHTNING? 151 
 
 silently at a much greater than the striking distance, 
 and so prevent its descending towards the punch ; or 
 if in its course it would come nigh to strike, yet 
 being first deprived of its fire it cannot, and the 
 punch is thereby secured from the stroke ; I say, if 
 these things are so, may not the knowledge of this 
 power of points be of use to mankind, in preserving 
 nouses, churches, ships, &c., from the stroke of light 
 ning?" 
 
 Mr. Wilcke, who made some very acute remarks 
 on Franklin s views of electricity, states, that he 
 witnessed the result of this action of pointed bodies 
 on the great scale of nature, in August, 1758. A 
 large fringed cloud, strongly electrified, and extend 
 ing its inferior surface towards the earth, suddenly 
 lost its electrical character, in passing over a forest 
 of tall fir trees. The ragged and depending portions 
 shrank back upon the main cloud, and rose up, as it 
 were, from the earth.* 
 
 The great number of cases we have cited (pp. 118, 
 132), with a view of showing, not only the protecting 
 effect of lightning rods, but their passive character 
 as attractors of lightning, may be further adduced, 
 in illustration of this peculiar property of pointed 
 conductors. Indeed, it is almost impossible to ac 
 count for the fact of so many buildings being repeat 
 edly struck by lightning, before they were furnished 
 with lightning rods, and so seldom struck afterwards, 
 and that lightning has seldom, if ever, been observed 
 
 * FRANKLIN S Letters, p. 351. 
 
152 PHENOMENA OBSERVED WHEN 
 
 to fall in an explosive form upon buildings involving 
 pointed metallic conductors in their construction, 
 without admitting that the conductors had rapidly 
 neutralized the electrical state of the air, and so pre 
 vented the occurrence of a dense explosion. 
 
 We find this effect especially apparent (p. 118) 
 in the case of the tower of St. Mark at Venice, the 
 chapel of the Count Orsini, the temple of Jerusalem, 
 the monument of London, the cathedral at Geneva, 
 and many others ; and if we add to these the re 
 markable instances of certain ships of the British 
 navy, enveloped as it were in violent thunder 
 storms in tropical climates, without any dense ex 
 plosion falling on them, the evidence of this action 
 of pointed conductors, in mitigating the fury of 
 electrical discharges, is as complete as any evidence 
 from experience can be imagined. 
 
 We have deemed it worth while to thus extend 
 illustrations of the power of points to draw on, and 
 to throw off the electrical fluid, on account of the 
 intrinsic practical importance of the subject to the 
 community, who have churches and other public 
 buildings to protect, and to private citizens, who 
 have lives, houses, and various kinds of property ex 
 posed. For, without a due appreciation of this power 
 of points, no intelligent conviction can be had as 
 to the proper construction of lightning conductors. 
 
 Phenomena observed when a dense Explosion of 
 
 Electricity falls on a Lightning Rod. 
 Instances in which the forces have not been so 
 rapidly neutralized by the action of pointed bodies, 
 
EXPLOSIONS FALL ON A LIGHTNING ROD. 153 
 
 as to prevent some portion of the discharge from 
 falling upon the conductor in a concentrated form, 
 are by no means common : when they do occur, 
 however, the explosive action subsides in striking 
 on the point. The phenomena in such cases corres 
 pond accurately with those of artificial electricity, 
 and are of a highly interesting character. The 
 crash of the thunder is attended by a loud whizzing 
 sound, described by some observers as the rushing 
 of water, or like the sound heard on lifting the valve 
 of a steam boiler; at the same time the conductor 
 becomes covered with a luminous glow or streak of 
 light, and appears at the part struck to be enveloped 
 in electrical fire. 
 
 The luminous appearance was observed at an 
 early period of the application of lightning rods. 
 When the heavy discharge fell upon the tower at 
 Sienna, in 1777, several persons noticed upon the 
 conductor a long and regular train of light.* At 
 the time of the dense electrical explosions which fell 
 upon Her Majesty s ships Druid, Beagle, Dryad, 
 &c. (p. 130), the observers all agree in representing 
 the discharge as attended by a loud whizzing 
 sound, and upon the conductors a transient glow 
 of light. 
 
 These phenomena are easily produced by arti 
 ficial means. If we attempt to discharge a highly 
 charged jar through a pointed rod, a loud whizzing 
 noise, in the direction of the point, will be heard, 
 
 * TILLOCII S Mag., viii., p. 318. 
 7* 
 
154 HARMLESS CHARACTER OF THE LUMINOUS 
 
 immediately before the dense explosion takes place. 
 The production of the light is not so easily accounted 
 for; but the results of scientific inquiry favor the 
 opinion that it is a sort of glow, between metal and 
 air immediately in the points of contact ; that it is 
 of a perfectly harmless nature, and may be classed 
 with the phosphorescent flashes attendant on the 
 aurora borealis, or with the streaming of ordinary 
 electricity in the exhausted receiver of an air-pump. 
 It may be produced artificially on a conducting 
 wire, either by increasing the electrical charge, in 
 respect of the size of the wire, or diminishing the 
 atmospheric pressure. 
 
 Harmless Character of the Luminous Appearances 
 observed on Lightning Rods. 
 
 It is essential to distinguish between this glow 
 on the surface of lightning rods and the heat evolved 
 by the passing shock. We have already shown (p. 
 109) that no mass of metal, equal in conducting 
 power to a copper rod half an inch in diameter and 
 two feet in length, has ever been fused or even 
 sensibly heated by lightning;* and it is well known 
 that any quantity of electricity may be discharged 
 through a conducting rod, even whilst in contact 
 with the most inflammable compounds, such as gun 
 powder, &c., without igniting them, provided the 
 temperature of the rod be not considerably in- 
 
 * Shipwreck by Lightning, Report and Evidence, p. 13. 
 
APPEARANCES OBSERVED ON LIGHTNING RODS. 155 
 
 creased by the discharge. If the atmospheric pres 
 sure about such a wire be diminished, we immedi 
 ately observe it covered, at the instant of the 
 discharge, with a luminous glow, yet it is not sensi 
 bly heated, nor will inflammable matter in contact 
 with it be inflamed. 
 
 There are many interesting examples on record, 
 of the small degree of heat of this species of electrical 
 action. The St. Helmo s fires, and other electrical 
 lights which so often settle on the masts and ropes 
 of ships, are unattended by any calorific effect ; and 
 persons during electrical storms, have appeared to be 
 enveloped in weak flames, without being at the time 
 in any way conscious of it. 
 
 A remarkable instance of the harmless nature 
 of these appearances was observed by Boss and 
 Sabine, in returning from their last Arctic expe 
 dition. In the Greenland seas, during a dark, cloudy 
 night, they observed a sort of glow discharge on the 
 surface of the water, directly in the ship s course. 
 It appeared to occupy a space of four or five hun 
 dred yards, and had very considerable elevation. 
 The vessel at length sailed out of a pitchy darkness, 
 directly into this luminous mass ; all at once the 
 masts, yards, and sails, as the successive masts 
 passed forward, became covered with light. The 
 ship having sailed completely through it, became 
 again involved in profound obscurity.* 
 
 * Communication from Dr. Robison to Mons. Arago. Annuaire 
 for 1838, p. 372. 
 
156 DIVISION OF THE CHARGE. 
 
 This was evidently one of those glow discharges 
 already explained (p. 38). The deep black clouds 
 covering the sky being particularly indicative of 
 that peculiar condition of the atmosphere observed 
 in thunderstorms (p. 52) ; as evidence of the small 
 heating effect of this species of electrical light, the 
 result is very important and conclusive. 
 
 Division of the Charge. 
 
 Although there is no instance on record of an 
 isolated lateral explosion of electricity from a light 
 ning rod, yet we find instances in which the dis 
 charge has divided between the conductor, and other 
 metallic bodies in connection with the earth. 
 
 Arago, in his valuable u Notices sur le Ton- 
 nerre" published in the Annuaire of 1838, has 
 quoted an instructive case of this nature.* It ap 
 pears that for the protection of a house in the United 
 States of America, a lightning conductor had been 
 applied on the outside of the building, similar to 
 that represented in the annexed figure (16), in which 
 p is a pointed bar of iron projecting from the roof, 
 1ST, a similar bar driven into the ground, at P a 
 small brass wire connecting the bar. At the point 
 ??, inside the house, stood a fowling-piece, n, with its 
 barrel against the wall, and separated from the con 
 ductor P N only by the thickness of the masonry. 
 The consequence was, that when a discharge of 
 
 * FRANKLIN S Works, vol i., p. 361. 
 
DIVISION OF THE CHARGE. 
 
 157 
 
 lightning fell on the conductor at P, and passed on 
 the small wire P t, it divided at the point w, upon 
 the two circuits, and in doing this broke out a large 
 
 Fig. 16. 
 
 hole in the wall of the house, and shattered the 
 stock of the gun in forcing a passage to the earth. 
 The small wire P t was completely melted so far as 
 the point w,.but not beyond it ; the resistance in the 
 direction p t N, at the point of fusion of the wire, 
 evidently exceeded or was equal to the resistance in 
 the direction PHN- hence the metal in the fowling- 
 piece evidently saved the remaining portion of the 
 wire n t. 
 
 The cases quoted of the damage by lightning to 
 the Hotel des Invalides, at Paris (p. 101), to the 
 French frigate La Junon, as also the shock expe 
 rienced by the two sailors in the French frigate 
 La Calypso, are all instances of this division of 
 
158 BUILDINGS HAVING CONDUCTORS 
 
 the charge between the conductor and other lines of 
 transit to the earth or sea. It is quite clear, that in 
 these cases the resistance to the progress of the dis 
 charge through the small and very long ropes of 
 wire, exceeded, or was at least equal to, the resist 
 ance in other directions ; consequently, these in 
 stances are very similar to the preceding. 
 
 " I am not aware," says Faraday, in speaking of 
 such cases, " of any phenomenon called lateral dis 
 charge, which is not a diversion of the primary 
 current ;" " all liability to a division of the main 
 charge would decrease in proportion to the capacity 
 of the primary conductor."* 
 
 Instances in which Buildings provided with pointed 
 Conductors are said to have been damaged hy 
 Lightning. 
 
 Although several instances have occurred in 
 which buildings having pointed lightning rods have 
 been damaged by lightning, yet it is a singular fact, 
 that they may all be quoted in illustration of the 
 great advantage of such rods, in safely transmitting 
 heavy electrical discharges from the atmosphere. 
 
 We have shown, by reference to a variety of 
 cases, both the small influence of pointed con 
 ductors in attracting or causing explosions of light 
 ning, and the liability of the discharge to break up, 
 before reaching the earth, into two or more streams 
 
 * Report and Evidence on Shipwreck by Lightning, pp. 34, 35. 
 
DAMAGED BY LIGHTNING. 159 
 
 (pp. 135, 136). In the cases of damage by lightning 
 said to have occurred, notwithstanding the presence 
 of a pointed conductor, the electrical discharge has di 
 vided in the air into two or more streams, previously 
 to striking the building. One portion has commonly 
 struck upon the conductor, and been carried off by 
 it, whilst other portions have fallen on points far 
 distant from the conductor. 
 
 The first instance claiming attention, is the case 
 of the church of "Notre Dame de la Garde," at 
 Genoa, struck and damaged by lightning on the 
 14th August, 1779, a lightning rod having been ap 
 plied to it in the previous year. 
 
 The church stands on one of the highest hills in 
 the neighborhood of Genoa, and clouds are con 
 stantly hanging over it ; the bell tower to which 
 the conductor had been applied, was originally even 
 with the facade, but in consequence of a subsequent 
 enlargement of the church, and the erection of a 
 porch, it was thrown far back. The lightning con 
 ductor commenced from a stout iron rod, tipped 
 with a gilded copper point; this rod projected 
 from the top of the bell-tower three feet into the 
 air, and from its termination a stout iron bar was 
 continued, and led out through a window over the 
 roof of the church, and so on to the ground. Before 
 the lightning struck the church, it bifurcated (p. 
 36) ; one of the explosions fell on the conductor, split 
 open the gilded copper point, and was conducted 
 safely to the earth : the other explosion struck the 
 porch at a distance from the conductor, descended 
 
160 BUILDINGS HAVING CONDUCTORS 
 
 into the church, and did some damage ; several per 
 sons who were in a room over the porch felt a vio 
 lent shock, many were thrown down, but not hurt. 
 
 This account has been obtained from the Samm- 
 lungen zur Physik, for 1782 :* the writer states that 
 the accident was attributed to the conductor, but he 
 shows that if the conductor had not been there, 
 much greater damage must have ensued, and thinks 
 it is perfectly clear that the church was struck in two 
 places, first on the conductor ; secondly, upon the 
 unprotected porch. This case, therefore, does not 
 furnish any argument against the employment of 
 lightning rods, but rather shows their value, and 
 points out the necessity of securing the portions of a 
 building which are distant from the rod. 
 
 The case already alluded to (p. Ill) of the Board- 
 house at the Purfleet magazines having been struck 
 by lightning, in May, 1777, is another instance in 
 which a building furnished with a lightning rod was 
 damaged. From the description of this building, it 
 will be seen that the corner struck was forty-six feet 
 distant from the point of the conductor. Little or no 
 damage was done : a few stones only were displaced. 
 Now, there can be very little doubt but that the 
 conductor really carried off safely and silently a 
 great portion of the discharge ; it is impossible to ex 
 plain on any other principle how so small an amount 
 of damage ensued from so heavy a discharge as this 
 appears to have been, especially if we suppose it to 
 
 * Vol. ii., p. 688. 
 
DAMAGED BY LIGHTNING. 161 
 
 have been concentrated upon two clamps on a cor 
 ner of the building. The probability is, that the 
 discharge bifurcated, as in the preceding case ; and 
 whilst one division rushed through the conductor, 
 the other struck a distant point of the house. The 
 clamps on which it fell, were fixed in the coping- 
 stones of the parapet, and were about seven inches 
 above the lead gutters of the roof, which constituted 
 a portion of the general system of conduction to the 
 ground. 
 
 The discharge, in forcing its way through seven 
 inches of bad conducting matter to the lead beneath, 
 did some damage by an intermediate explosion, but 
 it was very inconsiderable ; had the iron clamps been 
 continued to the general mass of metal on the roof, 
 it is quite certain that no damage whatever would 
 have occurred. 
 
 In the account given of this case in the Transac 
 tions of the Royal Society, it appears that an observer 
 who witnessed the descent of the lightning, saw it 
 divide in some point, p (fig. 17), into " three fire-balls," 
 as he termed them. One of these struck in the direc 
 tion of the conductor at c, another damaged the corner 
 of the building at m, together with a shed at 5, and 
 the third struck upon the ground in front" of the 
 house, near a gate, at G.* 
 
 This was evidently an instance of the trifurcation 
 of lightning (p. 36), one of the divergent branches 
 or streams having fallen on the conductor. But this 
 
 * Phil Trans., vol. Ixxii., p. 377. 
 
162 
 
 BUILDINGS HAVING CONDUCTORS 
 
 part of the explosion was discharged safely into the 
 earth, whilst the shed s, and comer ra, which were 
 unprotected, suffered. This case, therefore, affords 
 
 FIG. 17. 
 
 4. DP DP OP 
 
 VF^ 
 
 conclusive evidence of the value of lightning rods. 
 The committee of the Koyal Society, in a report on 
 this circumstance, considered that the rods were not 
 so " perfectly applied as they ought to have been ;" 
 they were, however, sufficiently well applied to meet 
 any discharge of lightning likely to have fallen on 
 them. No part of the building near them was 
 damaged, and it is not to be expected that they 
 should defend parts at a great distance, especially 
 when such parts are the first exposed to an elec 
 trical cloud moving toward them, and likely to strike 
 upon them obliquely (p. 135). 
 
 The instance in which lightning fell upon a maga- 
 
DAMAGED BY LIGHTNING. 163 
 
 zine of powder at Bayonne, in February, 1829, fur 
 nishes another remarkable illustration of the liability 
 of the electrical discharge to divide in the air, and 
 strike on a part of a building distant from a light 
 ning rod, as well as on the rod itself. This case, 
 which was reported on by the physical section of the 
 Royal Academy of Sciences at Paris, gave rise to 
 much interesting discussion. 
 
 The building is about fifty-six feet in length, and 
 about thirty -six feet wide : it is covered by thick 
 vaulted masonry, and a sloping roof with gable ends: 
 these were protected by plates of lead ; the gutters 
 also were of lead, and there were the usual appen 
 dages for discharging the rain. 
 
 The lightning rod projected about twenty feet 
 above the building : it was attached to the lead of 
 the roof by a metallic socket, through which it 
 passed, and which was soldered to one of the lead 
 coverings. Instead of being carried, however, di 
 rectly into the earth at the foot of the wall, it was 
 turned outward, at about two feet from the ground, 
 and, being bent at right angles, was continued on 
 semi-insulating posts of wood into a trench filled 
 with charcoal, distant thirty-three feet from the wall. 
 
 On the 23d of February, 1827, about 4 A. M., a 
 discharge of lightning fell on this building. The 
 point of the conductor was melted, and the plates of 
 lead, by which it was attached to the wood posts at 
 the foot of the wall, were more or less torn and per 
 forated by holes. No damage, however, ensued to 
 the building in the course of the conductor. At the 
 
164 BUILDINGS HAVING CONDUCTORS 
 
 southwest corner, a sheet of lead covering the gable 
 end was torn out immediately over a point where 
 two stones of the cornice were united by an iron 
 cramp. Hence, as in the case of the magazine at 
 Purfleet, this distant part of the building was also 
 visited by an electrical explosion. 
 
 The reporters state, that the conductor, in conse 
 quence of being continued at so great a distance from 
 the building, did not offer a sufficiently easy line of 
 transit for the discharge to the earth, which is, they 
 think, evident, from the damage to the wooden posts 
 on which the conductor was supported : hence they 
 infer, that the discharge divided between the con 
 ductor on which it first struck, and the metals of the 
 roof, and that the small rent on the lead, on the south 
 west angle, was the result of this division, in a point 
 through which the electrical discharge found its way ; 
 that this is the more probable from the circumstance 
 of the rain having at this point beaten against the 
 walls, and so increased the facility of conduction by 
 means of a " sheet of water, to the ground."* 
 
 The following well authenticated instances of 
 recent occurrence, in which lightning has fallen upon 
 bodies in the vicinity of conductors, as well as upon 
 the conductor itself, are very similar to those just 
 described, and they furnish satisfactory evidence of 
 the nature of such cases. 
 
 Her Majesty s brig Racer, commanded by Cap 
 tain J. Hope, was struck by lightning in May, 1835, 
 
 * Annales de Chimie, tome xl., p. 391. 
 
DAMAGED BY LIGHTNING. 165 
 
 in latitude 39 north, longitude 63 west ; a chain 
 conductor was up at the mainmast. The electrical 
 discharge fell with destructive violence on the fore- 
 topgallant mast, distant from the conductor about 
 forty feet, at the same time sparks were seen on the 
 chain, and a rustling noise was heard throughout its 
 length* (p. 131). We have here a remarkable illus 
 tration of the nature of the accident at Purfleet. 
 The conductor evidently transmitted without explo 
 sion a great portion of the discharge, and conse 
 quently prevented the damage which must have en 
 sued, had the whole been concentrated on a single 
 unprotected point. 
 
 Dr. O Shaughnessy relates the following instance 
 of the bifurcation of lightning, f which, on examina 
 tion, will be found to have a very forcible application 
 to the case of the damage done to the magazine at 
 Bayonne. It appears that, in May, 1837, an electri 
 cal explosion divided upon two adjoining houses in 
 Chowringhee, East Indies; one of the houses not 
 having a lightning rod, in the occupation of Dr. 
 Goodeve, was struck and damaged, whilst the ad 
 joining house, tenanted by Mr. Trower, and to which 
 a lightning rod had been applied, escaped, although 
 a portion of the explosion fell on it with great vio 
 lence. "Dr. Goodeve, while walking in the veran 
 dah, saw the lightning strike Mr. Trower s conductor, 
 and at the same time strike his own house." The 
 
 * Ship s log, with remarks by Captain J. Hope, R. N. 
 f Reports to the Honorable the Court of Directors of the East 
 India Company. 
 
166 BUILDINGS HAVING CONDUCTORS 
 
 distance of the damaged part of Dr. Goodeve s house 
 from the conductor, appears, from a subsequent ex 
 amination, to have been sixty-six feet, about the 
 same distance as that in the case of the Heckingham 
 poor-house, just described. 
 
 This case so remarkably conclusive as to the 
 protecting effect of lightning rods, has nevertheless 
 been adduced as an evidence of their liability to 
 draw down greater discharges upon buildings than 
 they can transmit, thus causing damage to surround 
 ing bodies ; we have, however, already shown (p. 136), 
 that pointed metallic rods have no such attractive 
 influence, and that discharges of lightning are de 
 termined towards the earth by very different causes. 
 But even if it were true, that a pointed metallic rod 
 did invite or attract lightning towards it, still we 
 cannot suppose it to attract more than it can conduct, 
 since the attraction would entirely depend on the 
 superior conducting power of metals ; to assert, there 
 fore, that a conductor can draw towards it more light 
 ning than it can conduct, is to assert in other words 
 that it attracts more than it can attract, which is evi 
 dently an absurd proposition. 
 
 The last instance which Mr. Snow notices of 
 damage done by lightning to a building furnished 
 with a conductor, is the case of the Melville Monu 
 ment, in St. Andrew s Square, Edinburgh. It con 
 sisted of a pointed metallic rod, which passed through 
 the statue, and was connected with an iron chain 
 led through a hollow way in the staircase to the 
 ground. 
 
DAMAGED BY LIGHTNING. 167 
 
 On the 14th of July, 1837, an electrical explo 
 sion fell on this building, by which the wooden door 
 leading from the staircase to the platform of the 
 gallery was forced off its hinges, and the stones at 
 the top near the door were loosened. On examining 
 the conductor after the accident, it appeared that the 
 chain connecting the pointed rod with the ground 
 had been, by accident or design, drawn up for some 
 considerable distance through the hollow way in 
 the staircase, and coiled round a stick placed across 
 the top of the stone tube round which the stair was 
 built. The stick was so placed as to press against 
 the door leading to the platform, in order to keep it 
 shut. 
 
 The damage in this case, therefore, did not arise 
 from any failure in the principle on which the con 
 ductor was applied, but entirely in consequence of 
 the displacement of its inferior portion, which re 
 duced it to the condition of a semi-insulated mass of 
 metal. 
 
 A church in Connecticut, in which were assem 
 bled the congregation, was struck by lightning. 
 Prof. Brocklesby, of Trinity College, Hartford, who 
 related to the writer the circumstances, was in the 
 house at the time of the explosion. The spire had 
 a single round rod, running down to the ground. 
 The charge was oblique, and came in a direction oppo 
 site to the spire, and struck the end of the church 
 most remote from the steeple. But this instance 
 cannot be adduced as evidence against the principle 
 on which lightning conductors are applied, since, 
 
168 BUILDINGS HAVING CONDUCTORS 
 
 according to the known laws of electricity, the rod 
 could render no protection whatever the lightning 
 not coming within its sphere of attraction. 
 
 The writer would add the case of Mr. Platt s 
 house, in Deep Kiver, Connecticut, already alluded 
 to, under the head, " Ascending or Upward Stroke." 
 This instance has often been adduced, as an argu 
 ment against the efficiency of lightning conductors. 
 But nothing could be more unfair. I know not who 
 erected the two rods upon this house. A. M. Quin- 
 by, Esq., of this city, speaking of this instance 
 through the public prints, asserts, " that they were 
 Spratt s patent, put up by a Dr. Minor, of Hartford, 
 Connecticut; but they were so improperly con 
 structed and attached, that they could not be at all 
 responsible for the harm suffered by the building." 
 The disruptive charge being upward, and occurring 
 on the front side of the house, and the rod running 
 down only on the back side, the lightning had no 
 chance of getting on to the rod, except by going 
 clear round the house, or passing over the top. 
 Evidently, in attempting the latter, the force of the 
 charge passed into the building ere it could reach 
 the rod. Hence the destruction which followed. 
 
 This instance is thus noticed in an editorial of 
 the Saybrook Mirror, June 24, 1852 : 
 
 " Singular Freak of Lightning . During the shower 
 on Wednesday of last week, the house of A. J. 
 Platt, of Deep Eiver, was struck, doing considera 
 ble damage. It appeared to be what is called an 
 upward stroke, passing up the door-casing of the hall- 
 
DAMAGED BY LIGHTNING. 
 
 169 
 
 door, knocking off the plastering in the hall and 
 parlor, and thence, through the hall, the side of the 
 house, where the wing connects, to the corner of the 
 wing, passing down on a pillar ; and also at another 
 point into the sink, knocking off splinters, and loosen 
 ing the clapboards in various places. 
 
 "A singular feature is, that the house was 
 guarded by a lightning rod attached to each chim 
 ney, running down the roof, and from thence to the 
 ground ; and there is abundant evidence that the 
 electric current, in its progress, passed within some 
 six or seven feet of this rod, and that the protection 
 which it is claimed to give, was of no avail in this 
 instance. The rod is one of those put up by Dr. 
 Minor, who has also put up several in this village, 
 and we would like to hear his explanation of their 
 inefficiency in this case, as he claims them as superior 
 to any other. 
 
 " That there is sure protection in a conductor, we 
 believe, and it would be well for those about to 
 procure this safeguard, to ascertain that they procure 
 the best article, and have them rightly put up. It 
 is a matter which is not lightly to be passed over, 
 where the lives of people and property are at 
 stake." 
 
 In so long a period as three-quarters of a cen 
 tury, it is not to be expected that no casualties 
 should occur, either from a defective application of 
 the conductor, or from an explosion falling on some 
 part of the building at a distance from the c^ r 
 ductor. , 
 8 
 
170 PRECAUTIONS WHEN EXPOSED TO 
 
 Precautions when exposed to the action of Thunderstorms. 
 
 From circumstances of almost constant inquiry 
 attending thunderstorms, it is impossible to witness 
 one without some feelings of personal danger; in 
 this case attention to the following observations may 
 often be of service in relieving the mind from un 
 necessary fear, or in suggesting the necessary steps 
 to be taken for the prevention of accident. 
 
 The precautions generally offered by writers on 
 electricity, as necessary for the safety of those who 
 are exposed to the action of a thunderstorm, may be 
 thus enumerated : " shelter should not be taken under 
 trees, hedges, &c., for, should they be struck, such 
 situations are particularly dangerous ; at the same 
 time a person is much safer at about thirty or forty 
 feet from such objects than at a greater distance, as 
 they are likely to operate as conductors. Large por 
 tions of water also ought to be carefully avoided if 
 possible, and even streamlets that may result from 
 recent rain ; these are good conductors, and the height 
 of a human being connected with them, may some 
 times determine the course of the lightning. In a 
 house the safest situation is considered to be the 
 middle of the room ; and this situation may be ren 
 dered still more secure by standing on a glass-legged 
 stool ; but, as such an article is not in the possession 
 of many people, a hair mattress, or a thick woollen 
 hearth-rug makes a very good substitute. It is very 
 injudicious to take refuge, as some persons do, in the 
 
THE ACTION OF THUNDERSTORMS. 
 
 cellar during a thunderstorm, since the discharge is 
 often found to be from the earth to the clouds, and 
 many instances are recorded of buildings that were 
 struck having sustained the greatest injury about the 
 basement story. But, whatever situation is chosen, 
 the greatest care should be taken to avoid going 
 near the fire-place, since the chimneys are most likely 
 to attract the fluid, and even if there be no fire in 
 the grate, at the time, it should be remembered that 
 soot is a powerful conductor. The same caution is 
 necessary with respect to all large metallic surfaces ; 
 gilt furniture, bell wires, &c."* 
 
 Construction of Lightning Rods applied to Buildings. 
 
 But the most important and useful application 
 that has ever yet been made of the discoveries of the 
 electrician is in the method of securing buildings, 
 ships, &c., from effects of lightning. To the in 
 genuity of Dr. Franklin the world is indebted for 
 this invention, as well as for his discovery of the 
 identity of lightning and common electricity ; and 
 these are justly considered two of the grandest dis 
 coveries of last century. 
 
 As this subject is of the utmost importance, we 
 shall here quote the opinions of many of the most 
 eminent electricians who have written on the subject 
 of lightning conductors. Mr. Cavallo, speaking of 
 the proposal of Dr. Franklin, which we have just 
 
 * London Encyclopcedia, vol. 8, p. 59. 
 
1*72 CONSTRUCTION OF LIGHTNING RODS 
 
 noticed, remarks "that the reasonableness and truth 
 of such an assertion has been confirmed by numer 
 ous facts, and the practice of raising such conductors 
 has been found exceedingly useful, particularly in 
 hot climates, where thunderstorms are very frequent, 
 and the damage occasioned by the same too often 
 experienced. 
 
 " In regard to the construction of such conduc 
 tors, there have been some controversies among elec 
 tricians ; and the most advantageous manner of using 
 them has not, without a great many experiments, 
 and but very lately, been ascertained." Some phi 
 losophers have asserted that such conductors should 
 terminate in an obtuse end, that they might the less 
 invite the lightning from the clouds ; for such an 
 end will not attract electricity from so great a dis 
 tance as a sharp point. But other philosophers have 
 thought a pointed termination to be much preferable 
 to an obtuse one ; and their assertion seems, on the 
 following accounts, to be better founded. 
 
 " A sharp-pointed conductor, it is true, will attract 
 electricity from a greater distance than one with an 
 obtuse point, but at the same time will attract and 
 conduct it very gradually, or rather by a continued 
 stream, in which manner a remarkably small con 
 ductor is capable of conducting a very great quantity 
 of electricity ; whereas an obtusely terminated con 
 ductor attracts the electricity in a full separate body, 
 or explosion, by which it is often made red hot, 
 melted, and even exploded in smoke, and by such a 
 quantity as perhaps would not have at all affected it. 
 if it had been sharply pointed. 
 
APPLIED TO BUILDINGS. 173 
 
 " A sharp-pointed conductor certainly invites the 
 matter of lightning easier than an obtuse one ; but 
 to invite, receive, and conduct it in small quantities, 
 never endangers the conductor ; and the object of 
 fixing a conductor to a house, is to protect the house 
 from the effects of, and not the conductor from trans 
 mitting, the lightning. 
 
 "It is an observation much in favor of sharp- 
 pointed conductors, that such steeples of churches, 
 and edifices in general, as are terminated by pointed 
 metallic ornaments, have very seldom been known 
 to be struck by lightning; whereas others that have 
 flat terminations and have a great quantity of metal 
 in a manner insulated on the top, are often struck ; 
 and it is but seldom that they escape without great 
 damage. 
 
 "Besides these considerations a sharp-pointed 
 conductor, by the same property of attracting elec 
 tricity more readily than an obtusely terminating one, 
 may prevent a stroke of lightning, which the latter 
 is incapable of doing. 
 
 " A conductor, therefore, to guard a building, 
 should be fastened to the wall, not by iron cramps, 
 but by pieces of wood. If this conductor were 
 quite detached from the building, and supported by 
 wooden posts the distance of one or two feet from 
 the wall, it would be much better. The upper end 
 of the conductor should be terminated in a pyra 
 midal form, with the edges, as well as the point, very 
 sharp ; and if the conductor be of iron, it should be 
 gilt. This sharp end should be elevated above the 
 highest part of the building (as above a stack of 
 
174 CONSTRUCTION OF LIGHTNING RODS 
 
 chimneys, to which it may be fastened) at least five 
 or six feet. The lower end should go five or six feet 
 into the ground, and in a direction leading from the 
 foundation ; or it would be better to connect it with 
 the nearest piece of water, if any be at hand. If 
 this conductor, on account of the difficulty of adapt 
 ing it to the form of the building, cannot conven 
 iently be made of one rod, then care should be 
 taken, that, where the pieces meet, they be made to 
 come in as perfect a contact with one another as 
 possible ; for electricity finds considerable obstruction 
 where the conductor is interrupted. 
 
 " In ships a chain has often been used for this 
 purpose, which, on account of its pliableness, has 
 been found very convenient, and easy to be managed 
 among the rigging of the vessel ; but as the electri 
 city finds a great obstruction in going through the 
 several links, so that chains have been actually 
 broken by the lightning, their use is now almost en 
 tirely laid aside." 
 
 Mr. Cavallo gives with cordial approbation, the 
 following extract from the Earl of Stanhope s learned 
 work on electricity. As requisites for the proper con 
 struction of conducting rods for the preservation of 
 buildings from the effects of lightning he directs, (1.) 
 " That the rods be made of such substances as are 
 the best conductors of electricity. (2.) That the rods 
 be uninterrupted and perfectly continuous. (3.) That 
 they be of sufficient thickness. (4.) That they be 
 perfectly connected with the main rod. (5.) That 
 the upper extremity of the rods be as acutely pointed 
 
APPLIED TO BUILDINGS. 175 
 
 as possible. (6.) That it be very finely tapered. (7.) 
 That they be prominent. (8.) That each rod be 
 carried in the shortest convenient direction, from the 
 point at its upper end to the main rod. (9.) 
 That there be neither large nor prominent bodies of 
 metal upon the top of the building proposed to be 
 secured, but such as are connected with the conduc 
 tor by some proper metallic communication. (10.) 
 That there be a sufficient number of high and pointed 
 rods." 
 
 A very interesting report on the subject of 
 lightning conductors, was presented to the Koyal 
 Academy of Sciences by M. Gay Lussac. The in 
 formation contained in it may be regarded in many 
 respects as the most perfect we possess on the sub 
 ject. In this paper we learn " that the electric matter 
 tends always to spread itself over conductors, and to 
 assume a state of equilibrium in them, and becomes 
 divided among them in proportion to their form and 
 principally to their extent of surface ; and that hence 
 a body that is charged with the fluid being in com 
 munication with the immense surface of the earth, 
 will retain no sensible portion of it." 
 
 Gay Lussac defines a lightning rod " to be a con 
 ductor which the electric matter prefers to the sur 
 rounding bodies, in order to reach the ground, and 
 expand itself through it, and should descend without 
 any divisions or breaks in its length into water or 
 moist ground. When a conductor has any breaks 
 in it, or is not in perfect communication with a moist 
 soil, the lightning having struck it, flies from it to 
 
176 CONSTRUCTION OF LIGHTNING RODS 
 
 some neighboring body, or divides itself between 
 the two, in order to pass more rapidly into the earth. 
 
 "The most advantageous form that can be given 
 to the extremity of a conductor, is that of a sharp 
 cone ; and as iron is very liable to rust by the action 
 of air and moisture, the point of the stem would 
 soon become blunt ; and therefore, to prevent it, a 
 portion of the top should be composed of a conical 
 stem of brass or copper, gilt at its extremity ; and the 
 higher it is elevated in the air, other circumstances 
 being equal, the more its efficacy will be increased." 
 
 " The rod should be supported parallel to the 
 roof, at about six inches distance from it, by forked 
 stanchions ; and after turning over the cornice of 
 the building without touching it, should be brought 
 down the wall. In a dry soil, or on a rock, the 
 trench to receive the conductor should be at least 
 twice as long as that for a common soil, and even 
 longer, if thereby it be possible to reach moist ground. 
 Should the situation not admit of the trench being 
 much increased in length, others in a transverse di 
 rection should be made, in which the lower extremi 
 ties of the conductor are to be placed. In general, 
 the trench should be made in the dampest, and con 
 sequently, lowest spot, near the building, and the 
 water gutters made to discharge their waters over it, 
 so as to keep it always moist. Too great precaution 
 cannot be taken to give the lightning a ready pass 
 port to the ground, for it is chiefly on this that the 
 efficacy of a conductor depends."* 
 
 * London Encyclopedia, vol. viii., p. 61 . 
 
APPLIED TO BUILDINGS. 177 
 
 The importance of insulating lightning conduct 
 ors, seems to have been better understood by electri 
 cians, than the methods by which it is effected. 
 Some philosophers observe, that the insulation may 
 be effected by "having the iron fastenings of the 
 rod to the wall large and blunt, and covered with 
 two or three folds of woollen cloth steeped in, and 
 covered with melted pitch:"* others, "that the con 
 ductor should be fastened to the wall not by iron 
 cramps, but by pieces of wood. If the conductor 
 were quite detached from the building, and sup 
 ported by wooden posts the distance of one or two 
 feet from the wall, it would be much better."f 
 While others, still, have thought that a more perfect 
 insulation was secured by India-rubber, or by pass 
 ing the rod through the necks of glass bottles, and 
 more recently, through glass thimbles or rings, cut 
 vertically through the centre. If insulation is effected 
 by thus passing the conductor through glass, it is 
 much better that the glass rings be in two semi 
 circular parts than to have it whole ; for experience 
 has proved, that it is far less likely to be broken by 
 the sudden heat and violent expansion of air which 
 always precedes the electric fluid in a lightning dis 
 charge. If the lightning rod could pass round or 
 over glass caps, as the telegraphic wires do, it would 
 be better still. With such a mode of insulation, no 
 possible harm can result to the insulator, however 
 powerful the explosion. 
 
 * Encyclopaedia, vol. viii., p. 647. 
 \ London Jnci/clor>cedia, vol. viii., p. 61. 
 8* 
 
1*78 CONSTRUCTION OF LIGHTNING RODS 
 
 We close our remarks on the construction of 
 lightning conductors, with a quotation from Pro 
 fessor Sturgeon, Superintendent and Lecturer of the 
 Koyal Victoria Gallery of Practical Science, Man 
 chester, formerly Lecturer on Experimental Philo 
 sophy at the Hon. East India Company s Military 
 Academy, Addiscombe, &c., &c., &c. 
 
 " The subject of lightning conductors is a branch 
 of practical electricity of exceedingly high interest, 
 and demands the contemplation of the most pro 
 found electricians. Hitherto, however, little more 
 has been attended to than the erection of a pointed 
 rod of iron, without regard to situation, altitude, 
 diameter, inferior termination, or any of those theo 
 retical points essential to the efficacy and protection 
 of the conductors, so as to render it a safeguard to 
 persons and property against the most formidable 
 element of nature. 
 
 " Franklin, the inventor of lightning conductors, 
 first proposed, for protecting houses, churches, 
 ships, &c., from the stroke of lightning, to fix on the 
 highest parts of these edifices upright rods of iron, 
 made sharp as a needle, and gilt, to prevent rusting ; 
 and from the foot of these rods, a wire down the out 
 side of the building into the ground, or round one 
 of the shrouds of a ship, and down her side, till it 
 reaches the water. Would not these pointed rods 
 probably draw the electrical fire silently out of a 
 cloud before it came near enough to strike, and 
 thereby secure us from that most sudden and terri 
 ble mischief ? " 
 
APPLIED TO BUILDINGS. 179 
 
 This philosopher, however, subsequently recom 
 mended continuous iron rods, of about half or three- 
 quarters of an inch diameter; which he said "may 
 be fastened to the wall, chimney, &c., with staples 
 of iron. The lightning will not leave the rod, 
 a good conductor, to pass into the wall, a bad con 
 ductor, through the staples. It would rather, if any 
 were in the wall, pass out of it into the rod, to get 
 more readily by that conductor into the earth. 
 
 "If the building be very large and extensive, 
 two or more rods may be placed at different parts, 
 for greater security. 
 
 " Small ragged parts of clouds suspended in the 
 air between the great body of clouds and the earth, 
 often serve as partial conductors for the lightning, 
 which proceeds from one of them to another, and by 
 their help comes within the striking distance of the 
 earth or a building. It therefore strikes through 
 those conductors a building that would otherwise be 
 out of the striking distance. 
 
 "Long sharp points communicating with the 
 earth, and presented to such parts of clouds, draw 
 silently from them the fluid they are charged with ; 
 these parts of clouds are then attracted to the main 
 cloud, and may leave the distance so great as to be 
 beyond the reach of striking. 
 
 " It is therefore that we elevate the upper end of 
 the rod six or eight feet above the highest part of 
 the building, tapering it gradually to a fine sharp 
 point, gilt to prevent its rusting. Thus the pointed 
 rod either prevents a stroke from the cloud, or if a 
 
180 CONSTRUCTION OF LIGHTNING RODS 
 
 stroke be made, conducts it to the earth with safety 
 to the building. 
 
 " The lower end of the rod should enter the earth 
 so deep as to come at the moist part, and if bent un 
 der the surface so as to go in a horizontal line six or 
 eight feet from the wall, and then bent again down 
 wards three or four feet, it will prevent damage to 
 any of the stones of the foundation." 
 
 Of these instructions of the celebrated Franklin, 
 Prof. Sturgeon remarks, that " had he recommended 
 copper rods instead of iron, and directed them to be 
 kept clear of the building instead of being fastened 
 to the walls with staples of iron, perhaps no better 
 instructions could have been given ; as far, at least, 
 as an individual rod is concerned. But besides the 
 injury that buildings may receive from a flash of 
 lightning striking a conductor fixed close to the slates 
 and masonry, from lateral explosions, a conductor 
 consisting of a single branch only might be the 
 means of drawing down destruction to some parts 
 of the building before the lightning reached that 
 conductor. For, were the lightning cloud on one 
 side of the building, and the conductor on the other, 
 the lightning would neither go round nor over the 
 house to arrive at the conductor, unless it met with 
 greater resistance in a direct path, and as the desti 
 nation of lightning is frequently a greater distance 
 from the cloud, and its path considerably oblique, it 
 is possible that some part of its path might be 
 through a part of the building before it arrived at a 
 lightning rod which formed another part of its path. 
 
APPLIED TO BUILDINGS. 181 
 
 " Cases of this kind have occurred, and, conse 
 quently, may possibly occur again under similar cir 
 cumstances; therefore it seems to me that unless 
 lightning conductors be properly placed, and of 
 proper materials and dimensions, they may be the 
 means of causing the most destructive consequences 
 to those buildings they were intended to protect. It 
 is very seldom indeed that a flash of lightning proceeds 
 in a vertical path perhaps never. 
 
 " I never yet saw, or heard of, a vertical dis 
 charge of lightning ; they are frequently very ob 
 lique indeed. The lightning which damaged Saint 
 Michael s Church, at Liverpool, last year, was an ob 
 lique discharge, and struck the bronze cross at the 
 top of the spire, several feet from its top. 
 
 " There is such a display of ignorance in the erec 
 tion of tall spires, that it is almost a miracle that the 
 whole of them are not destroyed by lightning. The 
 upper clamps and strings of lead, the former uni 
 formly placed at intervals from each other, and the 
 latter wantonly poured into the crevices of the ma 
 sonry, render the spire a complete chain of alternate 
 links of metal and masonry from top to bottom : the 
 former inviting the lightning to the edifice, and the 
 latter offering facilities for the most destructive ex 
 plosions. From this very arrangement of the mate 
 rials in the steeples of Saint Michael s and Saint Mar 
 tin s at Liverpool, and in the steeple of Brixton 
 Church, have these three steeples been shattered by 
 lightning. If such modes of building tall spires be 
 indispensable to protect them from the power of the 
 
182 
 
 CONSTRUCTION OF LIGHTNING RODS 
 
 wind, conductors are quite as indispensable to pro 
 tect them from lightning. Three rods (copper best) 
 at equal distances from one another, from the top of 
 the spire to the ground, and united at the top, and 
 by one or two bands below, would secure each spire 
 from lightning on whichever side it approached. - 
 
 "Lightning rods however numerous about a 
 building, should have a general metallic union; they 
 then form a system of conductors in which the force 
 of the lightning would be divided, whichever branch 
 was struck. I have a beautiful experiment to offer 
 to your notice, illustrative of this fact. 
 
 The apparatus represented by fig. 18, consists 
 
 FIG. la 
 
 of a series of iron wire chains, so connected as to 
 form a system of conductors of many branches. 
 The chains hang vertically from a horizontal brass 
 wire, and their lower ends rest on a sheet of tin-foil. 
 The brass wire first receives the jars, and the tin-foil 
 carries it from the chains to the outside of the jar. The 
 electric fluid, whilst traversing this circuit, illumin- 
 
APPLIED TO BUILDINGS. 183 
 
 ates every chain in the system to the same extent, 
 showing that it is equally divided amongst them ; 
 and had there been ten thousand such channels, it 
 would have divided itself amongst the whole of them. 
 This experiment shows two or more interesting facts. 
 It proves that the iron scintillates at every link by 
 an electric discharge through a chain of that metal ; 
 and these scintillations discover to us that the fluid 
 - occupies, and passes through, every channel in the 
 circuit."* 
 
 That we may not omit any information on the 
 subject that may be deemed useful, we shall add 
 Mr. Morgan s method of preventing all possible dan 
 ger. The plan which Mr. Morgan proposes is, that, 
 whilst a house is being built, "the foundation of each 
 partition wall should be laid on a strip of lead, or 
 a strip should be fastened to the sides of these parti 
 tion walls. The strips should be two inches wide, 
 and at least a quarter of an inch thick, and closely 
 connected with each other. A perpendicular strip, 
 on each side of the house, should rise from the con 
 ductors to the surface of the ground; whence a strip 
 should be continued round the house, and carefully 
 connected with water-pipes, &c. The strips on the 
 sides of the house should then be continued to the 
 roof, which ought to be guarded in the same manner 
 as the foundation. The top should be surrounded 
 by a strip, which should be connected with every 
 edge and prominence, and continued to the sum 
 mit of each separate chimney." It is particularly 
 
 * Sturgeon s Lectures on Electricity. 
 
184 PRACTICAL DEDUCTIONS. 
 
 necessary to guard the chimneys; for Mr. Morgan 
 mentions a case in which a house that had been 
 guarded in most respects, according to the preceding 
 directions, except that the chimneys were unpro 
 tected, was struck with lightning, which entered by 
 one of the chimneys ; here it spent its fury ; but the 
 chimneys falling on the roof did considerable damage. 
 
 All electricians agree " that security is rendered 
 more perfect by having every piece of metal on the 
 roof in metallic connection with the conductor, and 
 continuous strips of lead built into every wall, and 
 connected to one another by horizontal strips com 
 municating also with the conductor."* 
 
 The only objection to this method of protection 
 is the expense. But even this is mainly obviated, 
 by having the conductors so constructed as to run 
 the whole length of the building on the ridge, with 
 branches to the chimneys, and duly elevated above 
 them ; and, in case of small buildings, continuing the 
 main rod on the ridge over the roof, down the oppo 
 site diagonal corners of the building to the ground ; 
 and if the building is large, by having rods ex 
 tend from the main rod on the ridge over each end 
 of the roof, down the four corners ; and having all 
 the conductors united to one another by a perfect 
 metallic union. 
 
 Practical Deductions. 
 
 1. The conductor should be made of good con 
 ducting substance. 
 
 * Encyclopaedia Britannica, vol. viii. p. 647. 
 
PRACTICAL DEDUCTIONS. 185 
 
 2. It should have great electrical capacities ; a 
 square rod requires less metal than a round rod. 
 
 3. It should be perfectly continuous, i. e., it 
 should have no breaks in the connections ; no links 
 or hooks, but a perfect metallic union of every part. 
 If a person should think that a ring of zinc near 
 these connections, improves the appearance of the 
 rod, there can be no objection, though there is no 
 other possible advantage. 
 
 4. It should be insulated from the building to be 
 protected, except from such masses of metal as are 
 likely to offer other lines of discharge. 
 
 5. It should have numerous lateral points : 
 one in six or seven feet will answer. The more nu 
 merous these points are, the greater the conducting 
 power of the rod. Besides, these lateral points pro 
 vide for an oblique discharge, each being as good a 
 receiving point as the higher point at the chimney 
 or other prominences. They also guard against a 
 lateral explosion, or a division of the charge, which 
 is liable to happen in case the rod is overcharged, 
 especially if it be fastened to the house with pointed 
 staples ; and in case of an upward stroke, the electric 
 fluid being discharged at so many different points, 
 no harm can possibly occur. 
 
 6. Its upper extremity should project freely into 
 the air; should be pointed ; and may be triangular, 
 somewhat similar to a bayonet ; or it may have seve 
 ral branches. The only scientific advantage in 
 having a branching head or point for the superior 
 termination, is this : all the points are not likely to 
 
186 PRACTICAL DEDUCTIONS. 
 
 become blunt at the same time. Some have sup 
 posed that the point should be magnetized ; and little 
 needles, called "magnets" have sometimes been 
 added. But it is difficult to see the practicability of 
 this recent discovery ; for most are aware, that mag 
 netized iron or steel soon loses its magnetic influ 
 ence. But, is there any truth or science in this 
 application of magnetism? If there is, we con 
 fess, that we have not been able to discover it in 
 any experiments in the laboratory ; neither can we 
 learn that the subject has even been mentioned by 
 any writer whatever, on the subject of electricity. 
 
 7. The upper termination should be plated with 
 silver or gold, to prevent corrosion. 
 
 8. Every branch rod running to chimneys, and 
 other prominences, should have a perfect metallic 
 union with the main rod. 
 
 9. In cases where metallic vane-spindles, or other 
 points exist, the conductor may commence from 
 these, and should be applied immediately to the part 
 to be protected, and not at a distance from it ; and 
 should be so applied, that a discharge of lightning 
 falling on the general mass, could not possibly find 
 its way to the ground through the building by any 
 circuit of which the conductor did not form a part ; 
 that is to say, the conductor should be so carried 
 over the several parts of the building, that the dis 
 charge could not fall upon it without being trans 
 mitted safely by the conductor. Hence, the rod 
 should run along the whole length of the ridge, and 
 
CONCLUDING OBSERVATIONS. 187 
 
 down to the ground, at least on two sides of the build 
 ing. If the building is large, it should run down on 
 each corner. 
 
 10. Every conductor running to the ground, 
 should terminate sufficiently beneath the surface, to 
 insure moisture in the dryest part of the season. If 
 circumstances permit, it should connect with a spring 
 of water, a drain, or some other conducting channel. 
 
 Concluding Observations. 
 
 "We have seen that electricity is, from various 
 causes, generated and set free in our atmosphere ; 
 and that individual clouds, and masses of clouds, are 
 often highly charged with electricity, and insulated 
 by the surrounding air. The earth and the sea are 
 good conductors of electricity ; and, generally speak 
 ing, their natural electricity is undisturbed. The 
 attraction, therefore, of the electricity of the clouds 
 for the opposite electricity in the earth or the sea, 
 may become so powerful as to break through the 
 resisting medium which intervenes. If the clouds 
 are above a mountain, or rising ground, this dis 
 charge of electric matter into the earth is often at 
 tended with the fusion of portions of the rocks which 
 crown these exposed summits. If a tree stands in 
 the stratum of air through which the cloud discharges 
 itself, the lightning passes through it, cleaving, and 
 bursting, and damaging it in its passage. If a house 
 obstructs its path, the electricity descends through 
 
188 CONCLUDING OBSERVATIONS. 
 
 its walls, and gilded pictures, and finds out any 
 matter, whether organized or unorganized, living or 
 dead, which is placed near its path, and is capable 
 of advancing it on its rapid and breathless errand to 
 the earth. If a living animal grazing, or a human 
 being walking in an open field, intervenes between 
 the overcharged cloud and the ground, the one or 
 the other will become the chosen path of this irre 
 sistible foe. If a ship floats under an electrified 
 canopy of vapor, it has less chance of escape than 
 the tree, the house, or the living being. 
 
 The only terms upon which we can meet this 
 relentless enemy, is an humble admission of its su 
 preme and irresistible power, and a resolution to 
 give it the freest and the fullest passport through 
 our territory. We must supply it, in short, with a 
 railway of metal, the only species of road upon 
 which it can travel with a suitable speed and a harm 
 less intention. The moment it ceases to find a con 
 ducting body, it begins its devastation among im 
 perfect or non-conducting substances, till it again 
 gets into a safe and easy path. 
 
 Truly was it an auspicious period when Dr. 
 Franklin raised electricity to the dignity of a science, 
 and connected it with that tremendous agency 
 which had so often terrified the moral, and con 
 vulsed the physical world. The thunderbolt had fre 
 quently descended from heaven upon its victims ; but 
 mortal genius, though it comprehended not the most 
 perfect method of constructing an electrical machine, 
 or a lightning conductor, had now learned to bring 
 
CONCLUDING OBSERVATIONS. 189 
 
 it down in chains, to disarm its fury, and to convert 
 it into a useful, and even a friendly element. 
 
 After a successful test of the utility of lightning 
 conductors on the house of Mr. West in Philadelphia, 
 with a mind quick to perceive and a heart true to a 
 sense of justice, how natural the congratulations of 
 Mr. Kinersley to Dr. Franklin. " Sir, I most heartily 
 congratulate you on the pleasure you must experi 
 ence on finding your great and well-grounded expec 
 tations so far fulfilled. May this method of security 
 from the destructive violence of one of the most 
 awful powers of nature, meet with such further suc 
 cess, as to induce every good and grateful heart to 
 bless Grod for the important discovery! May the 
 benefit thereof be diffused over the whole globe ! May 
 it extend to the latest posterity of mankind, and 
 make the name of Franklin, like that of Kewton, 
 immortal" 
 
 Upon a review of what has been advanced in the 
 course of these pages, relative to the nature of 
 thunderstorms and the operation of lightning rods, 
 it appears that buildings and other elevations are 
 struck and damaged by lightning, only in conse 
 quence of their being points in one of the termi 
 nating planes of a great electrical disturbance in the 
 atmosphere ; not from any property of attraction for 
 the matter of lightning, inherent in the substances of 
 which such elevations are composed : that light 
 ning rods remove, by the aptness of their parts, the 
 resistance experienced by the electrical discharge in 
 moving through less perfect conducting matter; 
 
190 CONCLUDING OBSERVATIONS. 
 
 and hence, by allowing a rapid and free neutraliza 
 tion of the opposite electrical powers, they prevent 
 the damage attendant on an obstructed action : 
 that the operation of such rods, being of a purely 
 passive kind, they can no more be said to invite or 
 draw down lightning upon the buildings to which 
 they are applied, than a rain-pipe can be said to 
 draw down or invite the rain which flows through 
 it: that such a passive property cannot be fairly 
 adduced as an argument against their general use : 
 that since lightning rods only operate in transmit 
 ting as much electricity as falls on them, they can 
 not be prejudicial to buildings, but must, on the 
 contrary, by a rapid annihilation either of the whole 
 or a part of the force in action, necessarily contribute 
 to security : that lightning, being nothing more 
 than the electrical discharge moving through bad 
 conducting matter, under an explosive form, the 
 tendency of a lightning rod is to deprive the dis 
 charge of this form from the instant it falls on the 
 point of the rod, and by converting it into an 
 evanescent current, through matter calculated to 
 assist its progress, to annihilate it as lightning 
 altogether. 
 
 In the treatment of this question, it was not pos 
 sible to avoid a frequent appeal to electrical action, 
 on the great scale of nature. If, therefore, the re 
 markable instances quoted, of lightning striking on 
 buildings and ships, should appear to be somewhat 
 numerous, and to be treated of in too great detail, 
 yet it must be recollected, that it is only by pursu- 
 
CONCLUDING OBSERVATIONS. 191 
 
 ing such a course that we can hope to arrive at de 
 ductions worthy of confidence. Hence it is, that in 
 the progress of these inquiries we have been led to 
 adhere carefully to a series of well-authenticated 
 facts, and by keeping strictly within the safe path of 
 inductive science, we have endeavored to throw some 
 further light on a subject of very great public im 
 portance, which has not been generally or fully ap 
 preciated. With respect to certain prejudiced views 
 and opinions which have been entertained of the 
 operation of lightning rods, we trust to have made 
 it appear that such opinions are founded on no 
 sound basis whatever, and that a judicious applica 
 tion of pointed conductors, both on land and at sea, 
 is not only desirable, but is, in a great variety of 
 cases, quite essential to the preservation of buildings 
 and ships from the ravages of lightning. 
 
 THE END. 
 
14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 
 LOAN DEPT. 
 
 This book is due on the last date stamped below, or 
 
 on the date to which renewed. 
 Renewed books are subject to immediate 
 
 General Ljbrary . 
 University of California 
 Berkeley 
 
I U I I