VOL. XLVn.] PHILOSOPHICAL TRANSACTIONS. . , 2gl 



were accompanied with very sharp pain. It seemed as if the commotion was the 

 greater, the nearer the thunder was to the bar. 



Letter 3. Dated St. Germain, June 20, 1752. — On the 26th of this month 

 there was a storm at two different times : the 1 st was at 3 in the afternoon, and 

 the second at half after 6. This storm, which came from the south-west, was 

 very inconsiderable : there were but 2 or 3 claps of thunder, either at 3 or at 6 

 o'clock. ; and there was a considerable interval between the lightning and the 

 clap, which showed that the thunder was at a great distance. Yet the effects of 

 the electricity were very violent, which we attribute to M. le Monnier's ingenious 

 apparatus ; which was as follows : 



It is certain that the greater the quantity of these bars, the greater is the 

 quantity of electricity furnished by the magazine. In the last experiment there 

 was a tin pipe of 7 feet long, and about 5 inches diameter. It was the 1 st ma- 

 gazine : the 2d consisted of 6 great bars of iron of 6 feet long each, placed in 

 parallel order on glass bottles. All these magazines communicated with the 

 iron wire, that descended from the little bar at the top of the great pole, des- 

 cribed in the last letter. 



The 26th of this month, at 3 afternoon, very lively sparks were excited, and 

 M. le Monnier set fire to spirits of wine. At 6 o'clock the Abbe M. went up 

 to a proper place, in order strictly to observe the intervals between the commo- 

 tions and the electricity. The clouds extended from the south and west to the 

 zenith of the pole, and the lightning came from a very distant part ; and, in 

 proportion as the clouds came nearer, the electricity was felt with very smart 

 shocks, but without light or regularity ; for sometimes none were felt for 2 or 3 

 minutes, and it was commonly with every flash of lightning that the commotion 

 was felt. But when the clouds had covered a considerable part of the heavens, 

 the commotions of the electricity succeeded very quickly with noise and sparks ; 

 though the thunder could scarcely be heard, because of its distance. It may 

 hence be judged how strong the commotions would be, if the clouds, which 

 produced the thunder, were nearer the bar. 



On June 2g there was another storm ; but the Abbe was not present at the 

 experiments made in the garden, being employed in a like experiment in his 

 chamber. He placed at his window, which was about 35 feet from the ground, 

 a bar of iron of 12 feet long, which received a very sharp iron wire of 6 feet 

 high ; the whole advanced into the street, by means of a wooden pole laid pa- 

 rallel to the horizon ; at the end of which was a glass tube filled with resin, to 

 receive the iron rod. The wire that hung from the extremitj' of the pole entered 

 into the chamber, and from thence into a gallery of 30 feet long. The electri- 

 cal magazine was in his chamber, and the iron wire, after several turnings, was 

 again brought thither. He had disposed of this wire in such a manner, that if 



p p 2 



