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A. Small, of London, to Dr. Franklin. close by means of oiled paper between, or Flash of Lightning that struck St. Bride's covering the joining on the canister; or if in Steeple.
barrels, then the barrels lined with thin sheet I HAVE just recollected that in one of our lead; no moisture in either of these methods great storms of lightning, I saw an appear- could possibly enter the powder, since glass ance, which I never observed before, nor ever and metals are both impervious to water. heard described. [am persuaded that I saw By the latter of these means you see tea is the flash which struck St. Bride's steeple. brought dry and crisp from China to Europe, Sitting at my window, and looking to the and thence to America, though it comes all north, I saw what appeared to me a solid strait the way by sea in the damp hold of a ship rod of fire, moving at a very sharp angle with And by this method, grain, meal, &c. if well the horizon. It appeared to my eye as about dried before it is put up, may be kept for ages two inches diameter, and had nothing of the sound and good. zig-zag lightning motion. I instantly told a There is another thing very proper to line person sitting with me, that some place must small barrels with; it is what they call tinbe struck at that instant. I was so much sur-foil, or leaf-tin, being tin milled between rolprised at the vivid distinct appearance of the lers till it becomes as thin as paper, and more fire, that I did not hear the clap of thunder, pliant, at the same time that its texture is exwhich stunned every one besides. Consider tremely close. It may be applied to wood ing how low it moved, I could not have with common paste, made with boiling-water thought it had gone so far, having St. Mar- thickened with flour; and, so laid on; will tin's, the New Church, and St. Clement's stee- lie very close and stick well: but I should ples in its way. It struck the steeple a good prefer a hard sickly varnish for that purpose, way from the top, and the first impression it made of linseed oil much boiled. The heads made in the side is in the same direction I might be lined separately, the tin wrapping a saw it move in. It was succeeded by two little round their edges. The barrel, while flashes, almost united, moving in a pointed the lining, is laid on, should have the end direction. There were two distinct houses hoops slack, so that the staves standing at a struck in Essex-street. I should have thought little distance from each other, may admit the the rod would have fallen in Covent-Garden, head into its groove. The tin-foil should be it was so low. Perhaps the appearance is plyed into the groove. Then, one head being frequent, though never before seen by your's, put in, and that end hooped tight, the barrel ALEXANDER SMALL would be fit to receive the powder, and when
the other head is put in and the hoops drove To Peter Franklin, Newport.
up, the powder would be safe from moisture Best Method of securing a Poroder Magazine This tin-foil is but about eighteen pence
even if the barrel were kept under water. from Lightning. -You may acquaint the gentleman that I imagine a pound of it would line three
sterling a pound, and is so extremely thin, that desired you to inquire my opinion of the best method of securing a powder magazine
or four powder-barrels. “I am, &c.
B. FRANKLIN. from lightning, that I think they cannot do better than to erect a mast not far from it, which may reach fifteen or twenty feet above Of Lightning, and the Methods now used the top of it, with a thick iron rod in one piece in America for securing Buildings and fastened to it, pointed at the highest end, and Persons from its mischievous Effects. reaching down through the earth till it comes EXPERIMENTS made in electricity first gave to water. Iron is a cheap metal; but if it philosophers a suspicion, that the matter of were dearer, as this is a public thing, the ex- lightning was the same with the electric matpense is insignificant; therefore I would have ter. Experiments afterwards made on lightthe rod at least an inch thick, to allow for its ning obtained from the clouds by pointed rods, gradually wasting by rust; it will last as long received into bottles, and subjected to every as the mast, and may be renewed with it. trial, have since proved this suspicion to be The sharp point for five or six inches should perfectly well founded; and that whatever
properties we find in electricity, are also the But there is another circumstance of im- properties of lightning. portance to the strength, goodness, and use This matter of lightning, or of electricity, fulness of the powder, which does not seem to an extreme subtle fluid, penetrating other have been enough attended to: I mean the bodies, and subsisting in them, equally difkeeping it perfectly dry. For want of a me fused. thod of doing this, much is spoiled in damp ma When by any operation of art or nature, gazines, and much so damaged as to become there happens to be a greater proportion of of little value.--If, instead of barrels it were this fluid in one body than in another, the kept in cases of bottles well corked : or in body which has most will communicate to large tin canisters, with small covers shutting that which has least, till the proportion be
comes equal; provided the distance between 1. Buildings that have their roofs covered with them be not too great; or, if it is too great, lead, or other metal, the spouts of metal contill there be proper conductors to convey it from tinued from the roof into the ground to carry one to the other.
off the water, are never hurt by lightning, as, If the communication be through the air whenever it falls on such a building, it passes without any conductor, a bright light is seen in the metals and not in the walls. between the bodies, and a sound is heard. In When other buildings happen to be within our small experiments, we call this light and the striking distance from such clouds, the sound the electric spark and snap; but in the fluid passes in the walls, whether of wood, great operations of nature, the light is what brick, or stone, quitting the walls only when we call lightning, and the sound (produced it can find better conductors near them, as at the same time, though generally arriving metal rods, bolts, and hinges of windows or later at our ears than the light does to our doors, gilding on wainscot or frames of piceyes) is, with its echoes, called thunder. tures, the silvering on the backs of looking
If the communication of this fluid is by a glasses, the wires for bells, and the bodies of conductor, it may be without either light or animals, as containing watery fluids. And in sound, the subtle fluid passing in the substance passing through the house, it follows the diof the conductor.
rection of these conductors, taking as many in If the conductor be good and of sufficient its way as can assist it in its pássage, whether bigness, the fluid passes through it without in a strait or crooked line, leaping from one hurting it. If otherwise, it is damaged or des- to the other, if not far distant from each troyed.
other, only rending the wall in the spaces All metals, and water, are good conduc- where these partial good conductors are too tors.--Other bodies may become conductors distant from each other. by having some quantity of water in them, as An iron rod being placed on the outside of wood, and other materials used in building, a building, from the highest part continued but not having much water in them, they are down into the moist earth, in any direction not good conductors, and therefore are often strait or crooked, following the form of the damaged in the operation.
roof or parts of the building, will receive the Glass, wax, silk, wool, hair, feathers, and | lightning at its upper end, attracting it so as even wood, perfectly dry, are non-conductors: to prevent its striking any other part; and afthat is, they resist instead of facilitating the fording it a good conveyance into the earth, passage of this subtle fluid.
will prevent its damaging any part of the When this fuid has an opportunity of building. passing through two conductors, one good and A small quantity of metal is found able to sufficient, as of metal, the other not so good, conduct a great quantity of this fluid. A it passes in the best, and will follow it in any wire no bigger than a goose-quill has been direction.
known to conduct (with safety to the building The distance at which a body charged with as far as the wire was continued) a quantity this fluid will discharge itself suddenly, strik- of lightning that did prodigious damage both ing through the air into another body that is above and below it; and probably larger rods not charged, or not so highly charged, is dif- are not necessary, though it is common in ferent according to the quantity of the fluid, America, to make them of half an inch, some the dimensions and form of the bodies them- of three quarters, or an inch diameter. selves, and the state of the air between them. The rod may be fastened to the wall, chim-This distance, whatever it happens to be, ney, &c. with staples of iron.-The lightning between any two bodies, is called their strik- will not leave the rod (a good conductor) to ing distance, as, till they come within that pass into the wall (a bad conductor) through distance of each other, no stroke will be made. those staples.-It would rather, if any were
The clouds have often more of this fluid in in the walls, pass out of it into the rod to get proportion than the earth ; in which case, as more readily by that conductor into the earth. soon as they come near enough (that is, with If the building be very large and extenin the striking distance) or meet with a con- sive, two or more rods may be placed at difductor, the fluid quits them and strikes into the ferent parts, for greater security. earth. A cloud fully charged with this fluid, Small ragged parts of clouds, suspended in if so high as to be beyond the striking distance the air between the great body of clouds and from the earth, passes quietly without making the earth (like leaf gold in electrical expe: noise or giving light; unless it meets with riments) often serve as partial conductors for other clouds that have less.
the lightning, which proceeds from one of Tall trees and lofty buildings, as the towers them to another, and by their help comes and spires of churches, become sometimes within the striking distance to the earth or a conductors between the clouds and the earth; building. It therefore strikes through those but not being good ones, that is, not convey conductors a building that would otherwise ing the fluid freely, they are often damaged. I be out of the striking distance.
Long sharp points communicating with the , in an age of so much knowledge and free inearth, and presented to such parts of clouds, quiry !" drawing silently from them the fluid they are charged with, they are then attracted to the cloud, and may leave the distance so great as
Answer to the above. to be beyond the reach of striking.
- It is perhaps not so extraordinary that It is therefore that we elevate the upper unlearned men, such as commonly compose end of the rod six or eight feet above the our church vestries, should not yet be acquainthighest part of the building, tapering it gra- ed with, and sensible of the benefits of metal dually to a fine sharp point, which is gilt to conductors in averting the stroke of lightning, prevent its rusting.
and preserving our houses from its violent efThus the pointed rod either prevents a fects, or that they should be still prejudiced stroke from the cloud, or, if a stroke is made, against the use of such conductors, when we conducts it to the earth with safety to the see how long even philosophers, men of exbuilding.
tensive science and great ingenuity, can hold - The lower end of the rod should enter the out against the evidence of new knowledge, earth so deep as to come at the moist part, per- that does not square with their preconcephaps two or three feet; and if bent when under tions; and how long men can retain a practhe surface so as to go in a horizontal line six or tice that is conformable to their prejudices, eight feet from the wall, and then bent again and expect a benefit from such practice, downwards three or four feet, it will prevent though constant experience shows its inutility damage to any of the stones of the founda- A late piece of the Abbé Nollet, printed last tion.
year in the memoirs of the French Academy A person apprehensive of danger from of Sciences, affords strong instances of this : lightning, happening during the time of thun- for though the very relations he gives of the der to be in a house not so secured, will do effects of lightning in several churches and well to avoid sitting near the chimney, near other buildings, show clearly, that it was cona looking-glass, or any gilt pictures or wains- ducted from one part to another by wires, cot; the safest place is the middle of the gildings, and other pieces of metal that were room (so it be not under a metal lustre sus- within, or connected with the building, yet in pended by a chain) sitting in one chair and the same paper he objects to the providing melaying the feet up in another. It is still talline conductors without the building, as safer to bring two or three mattrasses or beds useless or dangerous.* He cautions people into the middle of the room, and, folding them not to ring the church bells during a thunder up double, place the chair upon them; for storm, lest the lightning, in its way to the earth, they not being so good conductors as the walls, should be conducted down to them by the bell the lightning will not choose an interrupted ropes,f which are but bad conductors; and yet course through the air of the room and the is against fixing metal rods on the outside of bedding, when it can go through a continued the steeple, which are known to be much betbetter conductor, the wall. But where it can ter conductors, and which it would certainly be had, a hammoc or swinging bed, suspend choose to pass in rather than dry hemp. And ed by silk cords equally distant from the walls on every side, and from the ceiling and floor * Notre curiosité pourroit peut-étre s'applaudir des above and below, affords the safest situation a nèrre, et sur la mécanisme de ses principaux effets,
recherches qu'elle nous a fait faire sur la nature du ton. person can have in any room whatever ; and mais ce n'est point ce qu'il y a de plus important; ii what indeed may be deemed quite free from vaudroit bien mieux que nous puissions trouver quel.
que moyen de nous en garantir; on y a pense; on s'est danger of any stroke by lightning.
méme fatte d'avoir fait cette grande découverte ; mais B. FRANKLIN.
malheureusement douze années d'épreuves et un peu Paris, Sept. 1767.
de réflexion, nous apprennent qu'il ne faut pas compter sur les promesses qu'on nous a faites. Je l'ai dit, il y a long temps, et avec regret, toutes ces pointes de fer
qu'on dresse en l'air, soit comme electroscopes, soit Professor Winthrop to Dr. Franklin.
comme préservatifs, sont plus propre à nous attirer St. Bride's Steeple.- Utility of Electrical con
le feu du tonnerre qu'à nous en préserver; et je perductors to Steeples.—Singular kind of Glass du feu dont elle est chargée, n'est pas celui d'un phy
siste å dire que le projet d'épuiser une nuée orageuse Tube.
sicien.--Memoire sur les Effets du Tonnerre. January 6th, 1768. Les cloches, en virtu de leur bénédiction, doivent I HAVE read in the Philosophical mais l'église permet à la prudence humaine le choix des
écarter les orages et nous preserver des coups de foudre; Transactions the account of the effects of momens où il convient d'user de ce préservatif. Je ne lightning on St. Bride's steeple. It is amaz- sais si le son, considéré physiquement, est capable ou ing to me, that after the full demonstration ment de son feu vers les objets terrestres, mais il est ceryou have given, of the identity of lightning tain et prouvé par l'expérience, que la tonnerre peut tom and of electricity, and the power of metalline ber sur un clocher, soit que l'on y sonne point; et si cela conductors, they should ever think of repair- danger, parcequ'ils tiennent des cordes par lesquelles la ing that steeple without 'such conductors.
commotion de la foudre peut se communiquer jusq's
eux: il est donc plus sage de laisser les cloches en reHow astonishing is the force of prejudice, even pos quand l'orage est arrivé au-dessus de l'église. Dich
though for a thousand years past bells have hand, and the other a little elevated above the been solemnly consecrated by the Romish level, a constant succession of large bubbles church,* in expectation that the sound of such proceeds from the end in the hand to the other blessed bells would drive away those storms end, making an appearance that puzzled me and secure our buildings from the stroke of much, till I found that the space not filled lightning; and during so long a period, it has with water was also free from air, and either not been found by experience, that places with filled with a subtle invisible vapour continuin the reach of such blessed sound, are safer ally rising from the water, and extremely than others where it is never heard; but that rarefiable by the least heat at one end, and on the contrary, the lightning seems to strike condensable again by the least coolness at steeples of choice, and that at the very time the other; or it is the very fluid of fire itself, the bells are ringing ;t yet still they conti- which parting from the hand pervades the nue to bless the new bells, and jangle the old glass, and by its expansive force depresses the ones whenever it thunders.-One would think water till it can pass between it and the it was now time to try some other trick ;- glass, and escape to the other end, where it and ours is recommended (whatever this able gets through the glass again into the air. I philosopher may have been told to the contra- am rather inclined to the first opinion, but ry) by more than twelve years experience, doubtful between the two. An ingenious artwherein, among the great number of houses ist here, Mr. Nairne, mathematical instrufurnished with iron rods in North America, ment-maker, has made a number of them not one so guarded has been materially hurt from mine, and improved them, for his are with lightning, and several have been evi- much more sensible than those I brought from dently preserved by their means; while a Germany. - I bored a very small hole through number of houses, churches, barns, ships, &c. the wainscot in the seat of my window, through in different places, unprovided with rods, have which a little cold air constantly entered, been struck and greatly damaged, demolished while the air in the room was kept warmer by or burnt. Probably the vestries of our Eng- fires daily made in it, being winter time. I lish churches are not generally well acquaint- placed one of his glasses, with the elevated ed with these facts; otherwise, since as good end against this hole; and the bubbles from protestants they have no faith in the blessing the other end, which was in a warmer situation, of bells, they would be less excusable in not were continually passing day and night, to the providing this other security for their respect- no small surprise of even philosophical spectaive churches, and for the good people that tors. Each bubbledischarged is larger than that may happen to be assembled in them during from which it proceeds, and yet that is not dimia tempest, especially as those buildings, from nished; and by adding itself to the bubble at the their greater height, are more exposed to the other end, that bubble is not increased, which stroke of lightning than our common dwell- seems very paradoxical. When the balls at each ings.
end are made large, and the connecting tube † have nothing new in the philosophical very small and bent at right angles, so that way to communicate to you, except what fol- the balls, instead of being at the ends, are lows. When I was last year in Germany, I brought on the side of the tube, and the tube met with a singular kind of glass, being a is held so as that the balls are above it, the tube about eight inches long, half an inch in water will be depressed in that which is held diameter, with a hollow ball of near an inch in in the hand, and rise in the other as a jet or diameter at one end, and one of an inch and fountain ; when it is all in the other, it behalf at the other, hermetically sealed, and half gins to boil, as it were, by the vapour passing filled with water.-If one end is held in the up through it; and the instant it begins to
* Suivant le rituel de Paris, lorsqu'on bénit des boil, a sudden coldness is felt in the ball held; cloches, on recite les oraisons suivantes :
a curious experiment, this, first observed and Benedic, Domine ...quotiescumque sonuerit, procul shown me by Mr. Nairne. There is somecursio turbinum, percussio fulminum, lesio tonitruum, thing in it similar to the old observation, I think calamitas tempestatum, omnisque spiritus procellarum,&c mentioned by Aristotle, that the bottom of a
Deus, qui per beatum Moisen, &c. procul pel. boiling pot is not warm; and perhaps it may binum, impetus tempestatum, iemperentur infesta toni help to explain that fact;-ifindeed it be a fact.
When the water stands at an equal height Omnipotens sempiterne Deus, &c. . tum ejus effugentur ignita jaculu inimici, percussio ful in both these balls, and all at rest ; if you wet minun, impetus lapidum, læsic tempestatum, fc. one of the balls by means of a feather dipt in Royale des sciences, que la nuit du 14 du 15 d'Avinde spirit, though that spirit is of the same temJa méme année, le tonnerreétoit tombé sur vingtquatre perament as to heat and cold with the water églises, dequis Landernau jusqu'à Sain! Pol-de-Leon in the glasses, yet the cold occasioned by the où l'on sonnoit, et que la foudre avoit épargné celles evaporation of the spirit from the wetted ball ou l'on ne sonnoit pas: que dans celle de Gouisnon, will so condense the vapour over the water qui fut entièrement ruinée, le tonnerre tau deui per contained in that ball, as that the water of the sonnes de quatre cui sonnoient, &c.--Hist. de l'Ac. R Jother ball will be pressed up into it, followed
ut ante soni.
dus. Sci. 1719,
by a succession of bubbles, till the spirit is above it. From the foot of this rod, a wire (the all dried away. Perhaps the observations on thickness of a goose-quill) came through a these little instruments may suggest and be covered glass tube in the roof, and down applied to some beneficial uses. It has been through the well of the staircase; the lower thought, that water reduced to vapour by end connected with the iron spear of a pump. heat was rarefied only fourteen thousand On the staircase opposite to my chamber times, and on this principle our engines for door, the wire was divided; the ends separatraising water by fire are said to be construct- ed about six inches, a little bell on each end; ed: but if the vapour so much rarefied from and between the bells a little brass ball suswater, is capable of being itself still farther pended by a silk thread, to play between and rarefied to a boundless degree by the applica- strike the bells when clouds passed with election of heat to the vessels or parts of vessels tricity in them. After having frequently containing the vapour (as at first it is applied drawn sparks and charged bottles from the to those containing the water) perhaps a much bell of the upper wire, I was one night greater power may be obtained, with little awaked by loud cracks on the staircase. additional expense. Possibly too, the power Starting up and opening the door, I perceivof easily moving water from one end to the ed that the brass ball instead of vibrating as other of a moveable beam (suspended in the usual between the bells, was repelled and middle like a scale-beam) by a small degree kept at a distance from both; while the fire of heat, may be applied advantageously to passed sometimes in very large quick cracks some other mechanical purposes,
from bell to bell; and sometimes in a contiB. FRANKLIN. nued dense white stream, seemingly as large
as my finger, whereby the whole staircase was enlighted as with sunshine, so that one
might see to pick up a pin.* And from the Experiments, Observations, and Facts, tending to support the Opinion of the utility but conceive that a numbert of such conduc
apparent quantity thus discharged, I cannot of long pointed Rods, for securing Build- tors must considerably lessen that of any apings from Damage by Strokes of Light, proaching cloud, before it comes so near as to ning.–Read at the committee appointed deliver its contents in a general stroke:-an to consider the erection of conductors to effect not to be expected from bars unpointsecure the magazines at Purfleet, Aug. 27, ed ; if the above experiment with the blunt 1772
end of the wire is deemed pertinent to the case. EXPERIMENT I. THE prime conductor of an electric machine, A, B (See the plate) being supported
The pointed wire under the prime conducabout 10 inches and a half above the table by tor continuing of the same height, pinch it a wax-stand, and under it erected a pointed between the thumb and finger near the top, wire 7 inches and a half high, and one fifth so as just to conceal the point; then turning of an inch thick, and tapering to a sharp the globe, the electrometer will rise and mark point, and communicating with the table; the full charge. Slip the fingers down so as when the point (being uppermost) is covered to discover about half an inch of the wire, by the end of a finger, the conductor may be then another half inch, and then another; at full charged, and the electrometer, c, (Mr. every one of these motions discovering more Henley's) will rise to the height indicating a and more of the pointed wire; you will see full charge: but the moment the point is un- the electrometer fall quick and proportionably, covered, the ball of the electrometer drops, stopping, when you stop. If you slip down showing the prime conductor to be instantly the whole distance at once, the ball falls indischarged and nearly emptied of its electri- stantly down tò the stem. city. Turn the wire its blunt end upwards (which represents an unpointed bar) and no such effect follows, the electrometer remain
From this experiment it seems that a ing at its usual height when the prime con- greater effect in drawing off the lightning ductor is charged.
* Mr. de Romas saw still greater quantities of light. ning brought down by the wire of his kite. He had "explosions from it, the noise of which greatly resem.
bled that of thunder, and were heard (from without) - What quantity of lightning, a high pointed into the heart of the city, notwithstanding the various rod well communicating with the earth may had the shape of a spindle eight inches long and five be expected to discharge from the clouds si- lines in diameter. Yet from the time of explosion to lently in a short time, is yet unknown; but I the end of the experiment, no lightning was seen above, have reason from a particular fact to think it of fire issuing from it were observed to be an inch may at some times be very great. In Phila- thick and ten feet long." See Dr. Priestley's History delphia I had such a rod fixed to the top of of Electricity, pages 134-136, first edition. my chimney, and extending about nine feet at Purfleet.
+ Twelve were proposed on and near the inagazines
At another tiine the streams