Observations upon Lightning, and the Method of Securing Buildings from Its Effects: In a Letter to Sir Charles Frederick, Surveyor-General of His Majesty's Ordnance, and F. R. S. By

Observations upon Lightning, and the Method of Securing Buildings from Its Effects: In aLetter to Sir Charles Frederick, Surveyor-General of His Majesty's Ordnance, and F. R. S. ByBenjamin Wilson, F. R. S. &Ac. R. Ups. Soc.Author(s): Benjamin WilsonSource: Philosophical Transactions (1683-1775), Vol. 63 (1773 - 1774), pp. 49-65Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/106137 .

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IS. OHervations upon Inqy, and the SIethfid of J2carzngBailifroan its m feSs: In a Letter to Sir Charies Frede- rick, Sarveyor-Ganeral of His Majy's Ordnance, and F. R S. Bv :g3enjamin Wilfon, Zi: :R. S. 89:X4c. R. UpE.;So¢.

S I R,

5ZOUR {lation, as Survestor*General of HXi6

] MajeRy's Ordnance, being fuch, as makes -the uEubjeEc: of this paper particulary intereRing to

you, I prefiume an apology for this addreEs will be wholly unntvceSary.

Upon an application of the Boardx of Ordnance to the Royal Society, in July; lall, a committee was ap- pointed, to con:fider of the propereR method fbr fe_ curing the ne at PurJleet; from mifchief by lightning: which commitftee reported to thejcouncil of that leara.ed body, what they thougllt neceSary to be done upon that occafion. lNhe coancil) after- wardso tranfimitted to the board, a copy of that report, together wi.th another paper writkn by mybelf in collfequence tllereof.

OL. LXIIt. H Forb

* t

Z 49 ^



[ 5o 3

For, during the conElderation of that bur1nefs, fome doubts having arifen in lny nzind, with regard to the propriety of poznts, which were propofed to terminate the top of each conduEtor; and thoSe doubts being fovTnded upon experiments and obSer- vations, I could not con0ently fubrcribe to tllat reportS nor fupprefs my opinion, on a fubjeEt of fiuch itnportance.

Whatever may be tlle IEntiments of others re- fipedirlg thofe doubts, yet, they being the refult of my tnature conf1deration, I thought it Iny duty to pro- pofe thenz to the committee; and further to expreSs my diXent, in writing, to that particular part of their report: giving, at ehe fame timee fome of the prin- cipal reains for fuch diXent; and referring thems for further fatisfadtion on this fubjedS to a letter which is already publifEed in thetrranEadcions of the Royal Society

As that dilIent is the origln of this paper, a ccpy of it IS here inSerted. See page 48 of this Volume.

AGREEABLE to the declaration at the end of tlit above difl;ent,- I {hall now proceed to offier my further reafos3s for objeding to pointed condudrors.

Experience, eZhich is our belt guide in all phy- fical enquiries? IDut particularly in eled:trical ones, every day conviraces mes that sve knos*^ but little of that fubtile fluid, which operates fo Jecrerly, and at the fame tilule fio powterfully, upon the earth, anc! its atmofpkere I confefs that l aln even now lets acquainted >?itll tlae princ;ple of its adtoon, than I tho;}ght I was twenty years ago: the pnalleJZ diJ-

JUrence3



[51 1 fererces in the circlltzzliances of our experilllents, fre qucsntly catufing very xuaterial diffierences in their re- fults. Anal perhaps no one, wlzo has not applied his tlliJsd clofely to enquirie-s of:this klnd, could con- ceive how the po}'StitZg a piece of metal, or not, ould nzalie any material difference in the experiment.

The eledcrician has it always in his power to con- villce any one of the faft, who, througll inexperience, may be inclined to entertain the leaft fcruple about it: for evea from thoJe experiments to which it was t3zought proper to appealat the conzmittee, it appeared, that the difFerence in the effc6rs upon this fluid, between pointed and blunt-ed trletal,- is as lZtO r.

A thunder-cloud thereforeZ according to that reafoning, (the circumIlances of it being: fuppoSed to be nearly fimilar with what is called the prime-conduAor in thofe experiments), if it afted at I200 yards di- It-ance upon a point, would require a blun:te.d end to be blought within the diItance of loo yards; atld beyond thofe: limits, would paIs over it, without af- feEing it at all. On this occaf1on permit me to obterve, that the longer the conduAors are above any building, the more danger is to be apprehended from them; as they will in that caSe approximate nearer ia their:effeEts to thofe that are pointed. And that is one reafon why-ITwas not for adviling the propoSed conduecors at Purfeef, to be fo higll as fen feet abose the magaxines, and more particularly upon that building called the Board-houJe, - which Rands confiderably higher than the nagasines themSelsres.

But, before we advance farther into this fubje2, it may be proper to Ihew the reaSons for introdueing a

H 2 pointed



[ S ] poie22d vpparatusfi when the experiment upon lightning was firlt propoSed: what good confequences were derisred from that experiment: and why, upon further experiments and obSerarations, fiuch points ought now to be laid afide, when our intention is not to nake eleSncal encterumentss but by the means of condudors, to preyqerve buildings fro7n the dafzgeroas effeAs of lgghtning.

Dr. Franklin, in his conjeAures) that lightning and eleEtricity were one and: the fame fluid, confidered how he ffiould invite, or bring down and otleS the ightntng, fo as to make experiments upon lt.

And he concluded, from obServation,, that the likelieflc method would be, to make uSe of fuch an apparatus. for the purpefe, as was moll Dfufceptible of eleEtric effedts; or, in other words, fuch an ap paratus as would rective the eled:ric fluid with the greate: eafev - - Repeated experiments taught bim, that metals had the property of receiving that fluidX with more eaSe than other fubAances.

He alfo learntX from the like experience, that metals by betng pointeds were rendered Rill nlore fuS- ceptible of receiving it

And thereforeX he - propofed an experiment to be tried, cs Whether it was not in ollr powet to invite, z; or bring down the lightning, by an apparatus, fs confifiing of an eleSrxc fland, and an iron rods {s- twenty or thirty feet in length, rifing upright sc from tlwe nliddle of the llandt and at the tops zc terminating in a veryvrp point" This apparatus was rccommended tQ be put upon fQme high

s * *

Dulldlngs



[ 53 3 building, with the expedatiorl, that if a thunder- cloud {hould happen to paSs near this apparatus, fonle quantity of the lightning depof1ted therein would probably be colledred in the rod, by -nzeans of the rery {harp point, and the eleEtrical fiand at the foot of the rod

That this contrvance anfwered the end he firk propoSed, we have had fuflicient evidence.

And it is n.o wonder if afier this great diScovery, we find binz, and other eleXtricians purfuing new experiments of this kind, and raifing thoId points higher into the air, to colled; llill greater quantities of that fluid which occa6}ons lightning. Nor neeel we be furprized,- after knowing that lightning coulQl be brought dvwn from the heavens by fo fi-mple an apparatus, aad after experiencing in fubvile effb2s to be flmilar with the eleEtric fluid, that tlle Ame- ricans, and others, upon Dr. Franltlins recommenda- tionX adopted the principlXe of iecuring their buildXingF from its dangerous eiedls, by raifing above their holltes rods of irons very Jbp poxnti and apply- ing wzres fFom the ends of thc)* rodsX down the out- fide of their hoifes,. to fthe ground

But though tlere appeared many argumeDts at thae time in fi-vour of Iuch conduEtors, yet experiments and obSersration-s, at 1a{t} induced lJr. Frank- lin to alRr his opinXS in refpedt to thofe qvgrs5, allA to IbbRitute in their place rods og lr9a: {lill retaining the principle of hauing tlae rods at the top WX p"ated; and many of the Anlericans, as well as Europeans, approved of the alteration, as appeatsed afterwards) fronl conRtuEti:ng their coduditors ac_ cordingly.

About



[ sA-] Absue that titne great attention was gisren, and

nzany new experiments were made, in con{Equence of the fireqvlent dangerous cff:bEts, which lightning wtas ob(il*ved to produce in fotne valualule buildings, by rendillg and daihing to pieces very large ttones and timbers, wllich were connedted togethAr by claaxps alld lzars of iron: and at other times breakt ing and melting part of thofe rodss and fotnetimes eelbdit?g wres, even of a confiderable thiclneEs, like {o much gunpowder

From^ carefill oblErvations of thefe extraordinary appearances produced by violent fhxks of lightning >

and upon lllaking other experiments relating to a certain refiRing po6ver t8, or upont all idiess which appears to adt againt} the attacks of lightning, as well as againIt the eleEtric fluid philobphers were enal)led to aElgn the reafon) and, it is apprehended, upon a Iblid f6undation, why ConduEtors lllould be made of mebl in prefErence to all other materials; as the power of refiRing Xch attacks is leIi in metals than in wood,

t

;one, or marv,e- And that this reflcance might be the more fimple

alld uniform, it appeared the mo(t eligible to have the condudrors made of om Mzued ptse of me- 21 x0, and of an equzzl dter thro#gogt But what that diameter ought to be, depcnded upon otller circumRances, fiome of which are taken notice Of itl a former paper, referred to above, which I laid beAre tlle Royal Society.

By this hiIlorical nectch we ie the propriety of e Dr. FraIlklins intriucing points, atld the advantage philoSizphy has dcrived from them:. by aScertaining

7 that



- -

l . 55 j

that lightning an(l cleAricity are one and tlle lame fllid: whicll appears to be diffbled every svllere, at leaI} upon this earth and itl fZJe oth¢e.

But sarhen curioJsty, wllich I apptehend was one nf the fil{t tnotives for itltrMucillg points to invite the lightning, was fatisfed; and experzence had taught us that we had it in our power to colZeS that fluid which occaf1ons it: and when the prtntpMe of its adcion was from experiments thus invelligated and v/^certvzzed, this manner- of insttatXon, viz. by ufing points, ought, intnyopiniorl, tohaveve*; becaufe a greater quantity of lightnixlg, than we have yet experienced, Inay chance to attack us.

For we are fo far from knowing how great the magazine of lightnlng may be in the heavens, or in the earths when it is ready to diiharge itSelf; either ^ . . by one or more exp ot1ons, t wat we are jgnorant, ewn of the quzXty vAual ; wrhenever any firoke from lightning vifits us,

Nor can the abJeft philofopher , zbe limits of tlle

greatffl aWhage that may poEbly happeI. Seelng then how valn lt iS tV look for any tlilzg

like aMlUFfe artty, in all cafes, it fa}relg belloves us to proceed with caution. And it is fc)r tllat reafoll? I have always confidered poillted collduders as being unJ+, by their great readi)lefs to co t/e ehX^, a too powe+I a maxner. And leIi the cotzduEtors ithout fubh pOillth {llould be too nendur fol wcry

* UnTefs wbere the eleAric ian, like z of r Ra<,, 1Na ( Kvlla was ktlle(l by it) at his aIn bazRrgl, clluts o ,;11ê fllst8xer tb_ i'crvatiolls 011 Jit,}utnillg.

N ieletRt



-[ 56 1 violent attacks, in places of great confequence, I have always recommended ehe having them above

fbur {tSM5 larger in diameter, than what are mmZ tnonly tnade uSe of, to the end our licurity may lDe the greater, by opening a larger paILage fbr any extraordinary dikharge, and fo fir lefIEning the danger to be apprehended fiom it.

I ought not, ln this place, to omie taking notice of a paper, containing ime irther experiments and ol)fersrations, which were produced at the committee, to lhew, among other thIngs, that pointed metals were more difpoSed to receive the lightning, by virtue of a repelzing prtnctpAe in the lightningX as well as the eledtric fluid, which aEted upon the natGral fuantY't

of the fluid contained within the metal, at a con fiderable -cliRance from the potnt, cauElng, if I may be alslowed the expreW;on, a kind of sazam therein; but I fuppoSe the author means eo a certain -diRance only.

So fir from difputing this philofophy, I readily admit tlae faft. --

But, I am afraid, amempt to prove that

pointed conduEtors may be fiQ difipIA t fxeive this fluid more readily, will not mend ehe argument in tlle leaft; becallSe, ehe more we leSen the power of re0ing, even fiuppoRing the whole ConduAor to be in that Itate, the more we increaSe s:he posver of invi- tation.

In regard to other experiments, with lods of co!- Xon * which arA afted upon in a particular manner

* Dr. Frarxklin's Expersluents. by



[ 57 ] by ie appoGtion of pointss and tS conclufions drawn kom thence, in fivour of pointed-condubr8 as callfing fimilar;effFXs upon the fragrts orfmAX c, which, hnging below the thunderclol3d$; have ien XppoX a kind of #etpfag-flones, fAr the lightning to paX upon, towards the- earth: fu pointed condudtors bein-g fiaJppo(Ed- to occafion thoX

frts to retire Wp tnto tbe cloud fbm whence they were iended :, and on that azount, to pret vent a Smkc Som- lightning, whtch might otherwilE hasre happeneds I+iball,+for the prefent, wave enw tering-intothisphilobphy, as I cnld wili0-theconw jEure- to be reconfidered; becau l apprehend it is liaKe to many objeftionss wh.ch t enumerat would carry me beyond the proper bounds d; fbch a paper asthis However, if thefame opinion Qlolild again be off¢red, and broug}lt in argument, it mv bc worth

while to enter more into dle-enquiry.

If tboti: gentlemen, -who artued at the cotnmittee for the .* Ff potnts, coul havc made it apzar gdlat fuch po1nts draw off; and condlldt away the

lightning and e r,- widbout cag . . ^ .

av c*n, durmg- a ehunder Itorm twhiO kems to have been once the opinion of- Dr. Franfiin3 I {hould readily bave fublEribed to their Repon. 0

But experience {hews UVs+: that tho faEt is oth£rZ wife: thex ing many inRancest wherx îiolent ezCP106iOnS Of 1i«tning have haPPened .eO ¢ono zors that WereS & Ad tHrX iX1 ParV tiCU1ar the aCCOUntS O WhlTh are iNferI it] a PUb11CatiOn Of DS. Hank1il1sS *, Where tHe po"ts

+ Dr hnlilini ExpNimentt, p. 39+ *X6, 7, Oc VDL LXI1I. I WSr£



[ 58 ] arere ffi*paXed or deJ?royed; atld a fmall part of a irotl rod melted next the points cxf one of them ;f. alld- alfo t the fes?eral crooked ends of the rods be- lossr, whele they were hooked on to each other,v

i and for;med the colldudor belonging to Mr. Maine ill North America. But as thofe letters are Iong, alld;cosltain feveral other cur-ious fad;tss I Ihall re- ierve them, together withSoInefurtherobServations UpOll the nature arld power of that re/g/?ing princ: ple, which is found to ad fcs felfibly againIt the attacks o f the ele-Etric fluidX or lightning, to Come futllre diflertation.

There is no building, that I know of, more ex- pofed to this kind of da\nger, than ttle EddyJisnc LighthouJ"e, as it Ilands upon a rock in the fea, feveral miles from lar}d. The fixing of a collduder to that building, was thought highly proper > and- the fixing of a point upon its as highly improper. Xt was therefore reColved upon to put u-p a conduAor wbos a poxnt, that 1lo tnore lighttlillg might be unnecelqarily -follicited to the-building, and that all the lightening; which acciclentally fell on it, might be conveyed away-without itliuriElg it. This-ton- duder wasfixed twelve years ago, andothe building has fince received no inJury from lightllinig *.

There is allother edifice of great confeq;uencet Iz mean St-. Paul?sChreh, which Itarxds much es- pofed from as heighth^-to; accidents by light- l*ng. The dean alld chapter of tllat cathedrale thougzht it an- objed defervillg the ferious attentioli

u N. B. A former bui]ding ereded for the famc purpoficy upon this ro¢ka was fetDn firc by lightning,.

of 3



[ 59 ] of the Rtyal SocteXyw A committee was thereforc appoillted, in confequence of their applicatioll: and proper condv-ors svere put ups in the Several places where they were thought neceflaryf from tlle top of the lanthorn to the Jsewers underground. And no-twithRanding particular care was-taken, to have tlle additional metal either of a confilder >able diameter or all equal quantity of xt formed winto o.ttler {hapes, for the conveniell-cy of-the ieve- ralplaces*; yet part of thoSe conduhrs, confiR- ing of iron, in theJ?one gullery, Ihewed marks of their havitJg been made co J derabUynhot, if-not ab- folutely red by a Ilroke of lightnitlg which hap- pelle(l in March lafi (as appears by a- letter wllich I commullicated to the Royal Society from one; of the veagers of that church Mr. Elichard Gould) who had examined the conduEcors :the mortling

following, alotlg with Mwr. 13urton of the fame ca- thedral * and Vthat the appearances were in geneb

ral,

* Mr. Gould acquaints ti3 in hisletter, that h: exam-ined tbe tCou;r canduAors in the lanthorn and Rone galle.ty d St.. Paul's Church, the morlling after the llghtning happened. That no marks whatfotsrer appeared upon tbe :conduEtor to the J*oath, which was the firk he attended to That he examined next the conduEtor to tFhe , and obfierved a tbiA rxJ^t lying upon the pave-ment in ehe flone gallery, as if it had been cleaneel os from the condud;or, with a tool-: that {e- seral parts of the iron appeared bl4ck, particularly the fctcws: or nuts: fomething like the eEeds lefi by gun-powder upon iron or Reel, or a fmoaky fireX

That the condudtor to the North, ffiewed no marks, no more than that to the Souths

But that upon examining the condudor to the t, he bund flronger marks abxndantly, thaXn on the F0t conduEtor,

I X it



[ 60 3

rals t5 the v-erger's letter reThred tliem- tc) rne. Mr Delaval and mySelf att.etided, about a week atter^wardsX :to 0bSer?e fhemX atld their -particulax

it- beitng much bbcEgr; particularly on thenuts and ferews: the^ r;uff Iying in greater quantities on the pavement. Ai?d tbe c tremeyart of the xnivhr ghat goes into the wder trtxk? ierned llke 9 pi-ce of iron ntwly takea out of ate by a fmit}z} without working it on ths anviJ.

NJ. B. Nlrs Gould has fince adde-d to- the account in hn )etter, fome citcum{'xances which t appFehend ought not to & conzittedv Ele fiys, that where the end of the- condudor, og the E:aR fide poin.ts towards the water trunlc a fl;orve (X*- ts*unds part af it, leavtng an interuals half aninchzwide or snore, between them, tnds about four or five inches long, whicb is a littie more ehan the breadth Qf the conduEtorX 'rhat this xnterval was filled ap wh dirt, and had been {ofor Some time, occaXioned by frequent ̂owers of rain waSbing the palrement in the kone-gallery. That, kfter-the 3it,htn ng liap*^ ?ened, he- obServed a hole was made throug,h tbe dirt, one wquaru kr of an4. inth in «lianeterfi arsd about two inches X length, ThAt the ho3e waB clofe to the uon; and -that,> upon §ooplng dowx his head he perceiv-ed a very difagreeable f ell of J>ulphur fiom the Rone} dirt, and condu2ur, p-articular)y the laR.

Upon hearing this account, Mrv Delaval and myfelf, a few days ago, vqent} and examined tt e conduEtorx agam but more carefully than beforev F<r, uponcaufing the kono to be reavved,. sYhich covered tbe top of the water trunk:,. we had an opportunity of exan;ining- llear two feet- more of the iron wbichpoin s. to tbe vva¢er trunk, than ute could per- ceive befgre tbis flone was temovtd. When we obServede tha£ the condvuding iron did not touch the lead. We like tvife cxbfervxd, that there was a wery thisk eva} of ru0t all at.er;

that part of the iron; particulary at tbe end ne*t. -the leads wbset e water entered the trrnl..

As the necelIlty of attending to-tllefe cir$umRancesS will be obvious to any oney who ii but tn the Icall: degree acquainted with thefie refearches, the dangerof negledlstg tbem wilZ bt h

a theyetro?SfeJet logbts by the gentlemtn-of the committeg wbo reco meadtd tne c0ndud0rs-fUr the fBcurity of tbat Gathedral.

.

tltu.atlon$



[ 61 ]

fituatiotls ; with tlle circulnllances attenditlg thems rhen we were very well fatisfied with his account, otwithRanditlg it had raitled in the saZerim fior

tllreedays together It is srorthy of note, that tluofe conduEtors did

not termxtate in a pognt, nor svas any po*nt put UpOtl

tlle 6s at tbe tap.-And yet Dr. Yratlklitu was of that conlInittee.

If poitlts are fe cfential to our fafety, why was not the reafotl enforced at the committee for having them orl that capital edifice ? For my part, I-think it was a happy circumRance, that there was na point: fixed UpOtl the tw of the church, to follicit a greater quantity of liglltnit3g at tllat monzent, than what fell upon the condudrors, cir eumShnced as they were: -as that 2xfrty was great enollgh to Zzat Jo conJiderably a bar of irorX nearfour itches brsag and about h4tf an gnch thick.

This powerfill effeEt, remindstmeofanother in- Rance IliCll more extraordinary, Wllich happened in Martinice, and ;5 related by Captain lDiDden, where a bar of iron, one inch in dianweter, wa. by a violene ffiockof Jightning redaced inone pZY of it, to the hckneyos of ajlerder wire only 9ee Ph Tr. Vol. LIV. P 25I

Since then wte are at all times igno-rant- of the quantity of l6ghf/ZgUgt gn the earth and its atmcEphere; and the difference in the effeds, bettsween blunted and pointed,- ends, tn caufinga diScllarge in our eledrica; experimerxts, appears to be: as one to trwglXve; it ss eaiy to cotnprclsend the very great rlanger this nobl tabsit;ld has Drc5ably ckape:d, by having no pc)illted appara;us -upon lt.

From



[ 62 ] From the above obServations, I am naturally led

to confider a part of the proceedings of the committee, refpeEting;the magasines at Purfleet; whea a certain number of condudrors, with tapering points at the top, saTere rerolved upon, as ne- ceiSary, toproteEt} the feveral buildings where -the powder is depofited. For it was agreed upon at the fame meeting, that the BoardhouJe, which is a large building for the uSe of the board officer&, and which llands confiderably higher than the magazines, as was obferved above, did not require az point at tZJe tOp: becaufe it was apprehended to be perfeSly Jsecare, by reafo-n of the copeings on the toof, the glltters and pipes to carry off the water, being all of lead: alld further, becauSe thoSe pipescom_ municated witb two wells, which always contained water.

I was not a little furprized at this laR refolution} which appeared to be fo inconfiRetlt with the former. BecauSet if points were lleceiLary in one placeX they ought to be l-o in another. And on the other hand, if the Board-houie i5 fecure by the leaden accidental condudrors, which have no points, why ought not the magazines to be equally Secure when put into the fame circumRances ?

I therefore enScxrced tile inconJ}J?ency of fuch a reSolution irlthe ArongeA terms. Notwithkanding which, the gentlenaen, at that time, thought pro per to contirsn their refolutionX However, at the next meeting of the committee, I obServed that they had been pleafed, in the mean time, to xnake atl amendment in favour of points for the board_

-houSe;



[ 63 ] houfie; which amendment was no fooner propofed, than approved of.

Why my obfervation was rejeded at the preced- ing meeting, I nlufi leave to the judgmene of others. 13ut it certainly cwarrics an appearance, as irZanZifeJt

contradiSion, upon further re-fledtion, mull have been the cv>Jê of that alteration.

And I am Sinclined to believe, from fome gentlemen of the cotnmittee exprel3;41ng their opsnion, sc of its heing a matter of mere indferenceX wbether sc blvnted or poznted cond>asrs xere made uge of" that they have not confidered this fubje&, with all the due attention which fo important an objedc deferves.

Forif ourexperiments Ihew, that points, from the nature of their se, and other circumRances attending them, re&It the attacks of this fluid leSs than blllnted ones;^ and that blunted condudors, of proper dimenElons, are fiufficient to convey away the lightning jafelyX whenever it attacks thenz; vvhy {hould we have recourSe to a method, which is at beR uncertain; and which fome tilne or other may be produ 9cive of the nlolR fatal effeEts ?

But perhaps no argumentcan be brought svith xnore force againflc the principle of polnts, than Dr, Franklin's own words, which are publEifhed in his experiments, p. 48i, where he declares poj MXsely.

<' 13uilEdings, that have their roofs covered with 4s lead, or other tnetal, and rpouts of metal conti- ' nued from the roof into the groulad to carry of

the water, are never Z:art by light-niag; as when_ " ever it falls on fuch a build:ing, it paffies in tlle 6t metals, and not in the walls." 0

This



r 64l This is tlle caf& with the BrfiiX MgJknx, a tbutld

ing al fo of confiderable con fequences where there are no other sondaPRors than what- are formed by- the copetgss gutters and pipes, which are all of lead, and communicate with the ground Now it is ;from the gteat quantity of metal contained in the feveral pipess together -with the other circumRances at- tcnding them, that l confidered thae building (in a former paper laid before the myal fociety) as being fufliciently fecureds from thofe dangerous accidents.

But if any gentlez3an {hould be diEpoSed to entertain a doubt about it, -or indeed of any her part af my reafoning on this fubieEt, a declaration of thoSe doubts may be attended with good confequences, as theywill lzectiSarily open the door to a more minute inveRigation.

I have nosr, Sir, gone through the rcafons which- I propofed- to lay before the royal focsety for the rejeding of points. And I- am very forrys in the courfe of this letter to have been under the ne- cety of mentloning any differences in opinion, which paXed between the nzembers of the committee, to whom this ilnportant matter was referr&d. I thinkX however, I {hall Rand excuSed to the fociety, and the public, when it appearss as I hope it now Iufficiently does, what my motive has been; namely, to tlate clearly, and impartially, the ob- jedrions which I sonceived to Iye againft pointed condudr-ors: and to dificloSe qvithozet any reJ2rque,

the prillciples on whick fuch objeEtions are grounded I ams S I R, with the greatell respeEt,

Your mo{t obedient, and mok humble fervant, 8th Decexnber, x772t Great Ruffiel-Rreett Benjamin WilfonO

* P*S.



f ds ]

P. S. Mr. Delaval. who was one of the committee, has given me leave to infert hts opinion upon thisfubjedc; which isthis. Thatheconcurs with me in thinking thar AIch conduEtors as am elevated bigher than she buildhgs X which they are applieds or are pointed at ffie topa are improper and dangerous.

He was defirous o£ delivering his opinion at the committee: but, as the meetings of it were held sn the iammer only, his abSenoe fi:om Lorldon preb wented his atntendanceX

.tr ns Vot LXIII



Documents

Observations upon Lightning, and the Method of Securing Buildings from Its Effects: In a Letter to Sir Charles Frederick, Surveyor-General of His Majesty's Ordnance, and F. R. S. By