VOL. LXVIII.] PHILOSOPHICAL TKANSACTIONS. 43^ 



house that had an accidental partial conductor within the inside of the upper part 

 of the house. It happened to a house near RatclifF Highway, on the 2gth of 

 July, 1773. In the uppermost room stood a large iron triblet, of about 3 feet 

 in height; the lightning made its way through the roof of the house, throwing 

 off a number of tiles, rending and tearing the laths and plaster on the inside, 

 to get to the triblet, on which it struck from thence to a hammer, which lay on 

 the floor near it: it then made its way, by partial conductors, down into the 

 cellar to the leaden pipe, which conveyed water from the main, and in its way 

 rent the house in various parts, so as to make it scarcely habitable. It left marks 

 of fusion on different metallic utensils. If the conductor from the triblet had 

 happened to have been made by a complete and sufficient metallic communication 

 with the earth, all parts of the house below would have been preserved; but the 

 parts above would have been equally rent and destroyed. 



Now to make a few remarks on Mr. Wilson's paper, intitled. New Experi- 

 ments and Observations on the Nature and Use of Conductors, Mr. N. says, in 

 p. 2 Mr. Wilson mentions, that he had declared his dissent in the year 1772 

 against pointed conductors. In answer to this I can only say, that from these 

 experiments of mine, the direct contrary appears to be the fact ; that the point, 

 instead of increasing an actual discharge, prevents a discharge where it otherwise 

 would happen ; and that the blunted conductors tend to invite the clouds charged 

 with lightning. The first ] 1 experiments of Mr. Wilson are intended to show, 

 that pointed conductors draw off the electricity from a cloud at a much greater 

 distance than those which are blunted. My Qth experiment proves the truth of 

 those experiments of his; the only difference is, that in mine the point acted on 

 my artificial cloud at a much greater distance; from which it appears, to use his 

 own words, p. 4, " that a charged body is exhausted of more of the fluid by a 

 pointed than by a blunted conductor." In answer to his 12th experiment, and 

 on to the 18th, where the model of the house moved swiftly, under his large 

 artificial cloud, and where the point was struck at 5 inches, and sometimes at a 

 quarter of an inch farther than his -^ ball; I must observe, that I have some- 

 times seen his apparatus at the Pantheon, with which he made his experiments, 

 strike as far to the -^ ball as the point; but in my experiments I have had it 

 strike 10 inches -rSj- to a point, and 10 inches and -j^ to a -jV ball; but to a 1 

 inch and -^ ball it commonly struck to 15, and sometimes to 16 inches. In 

 answer to the 18th and following experiments I must observe, that the substitute 

 being fixed is unnatural: for clouds are composed of a fluid matter, moving with 

 the utmost facility in another fluid substance; and from my 23d experiment, 

 where the substitute was fixed, the point was struck; yet in the 24th experiment, 

 where there was no other alteration than allowing the cloud to move freely, then 

 the point was not struck. I imagine, if Mr. Wilson's large artificial cloud at 



