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Show 498 07: 2‘58 735' of pointed Candi/flan in a conduitor of lightning, as we do of thofe proper for a cma'rrfz‘or of min, by putt obfervation. And as we think a pipe of three inches bore fuf. [M.P.] firming Bzu'iz/z'ngr fiam Lightning. 499 there may be in the bottle or glafs jar; yet neither the accumulation or the difcharge, ever exceeds ofzo feet, becaufe we never {aw fuch a pipe glut- the defiined quantity. Thus, were the clgmi'; always at a certain fixed dif'tauce from the earth ted by any fliower; to we mayjudge a conductor all difcharges would be made when the quantity ficient to carry off the rain that falls ona fquare of an inch diameter, more than fufl‘iCient for any accumulated was equal to the difiance: But there firoke of lightning that will fall on its point. It is true that if another deluge fhould happen is a Circumftance which by occafionally lefienin the diltance, leflens the difcharge; to wit, the wherein the windows of heaven are to be opened, inoveablenefs of the clouds, and their beinw draw n fuch pipes may be unequal to thefalling quantity; nearer to the earth by attraction when elegtrified - and if God for our fins thould think fit to rain fire fo that difcharges are thereby rendered more fre: quent and ofcoui‘fe lefs violent. Hence whatever upon us, as upon fome cities of old, it is not expeered thit our conduétors ofwhatever fize, {hould the quantity may be in nature, and whatever the fecure our houfes againf't a miracle-Probably as power in the clouds of collecting it,- yet an accumulation and force beyond what mankind has hi- water drawn up into the air and there forming clouds, is difpofed to fall again in mm by its natural gravity, as foon as a number of particles fuf- ficient to make a drop can get together; f0 when the clouds are (by whatever means) over or under- therto been acquainted with, is fearce to be expeé‘redi'é. Aug. 27, I772. B_ F. charged [with the elefiricflztm'] to a degree fufiicient to attraét them towards the earth, the equi- librium is reftored, before the difference becomes great beyond that degree. Mr.Lzme'.r elufiromctcr, for limiting precifely the quantity of a flock that is to be adminil'tered in a medical view, may ferye to make this more eafily intelligible. The dif- charging knob does by a {crew approach the conductor to the dittaiice intended, but there remains fixed. Whatever power there may be in the glafS globe to collect the fulminating fluid, and whatever capicity of receiving and accumulating It 1 ere "* [It may be fit to mention here, that the immediate occafion of the difputc concerning the preference between pointed and blunt conduélors of lightning, aroie as follows.-A powder mill having blown up atBrefcia, in confequence of its being ilruck with lightning, the Englifli board of ordnance applied to their painter, Mr. Willbn, then of fome note as an eleétrician, for a method to prevent the like accident to their magazines at Purfleet. Mr. Wilton having advifed a blunt conductor, and it being underfloor! that Dr. Franklin's opinion, formed upon the fpot, was for a pointed one; the matter was referred in 1772, to the Royal Society, and by them as nfual, to a committee, who, after confultation, prefcribed a me- thod conformable to Dr. Franklin's theory, But a harmlefs {troke of lightning, having under particular circumi'lances, fallen upon one of the buildings and its apparatus inMay 1777; the fubjeé‘t came again into violent agitation, and was again referred to the focieiy, and by the {ociery again referred to a new committee, which cummiitee S s s 2 confirmed |
