460 Professor Arthur Schuster [Feb. 22, 



WEEKLY EVENING MEETING, 



Friday, February 22, 1895. 



William Huggins, Esq. D.C.L. LL.D. F.R.S. F.R.A.S. Vice-President, 



in the Chair. 



Professor Arthur Schuster, Ph.D. F.R.S. F.R.A.S. 



Atmospheric Electricity. 



It is hardly possible to imagine that the first experimenter who 

 obtained an electric spark sufficiently strong to produce a sensible 

 sound should not at once have been struck by the fact that he 

 was in the presence of thunder and lightning on a small scale. We 

 find, indeed, in various writings from the early clays of electrical 

 machines a number of suggestions that the thunderstorm is an 

 electrical phenomenon ; but to Benjamin Franklin belongs the merit 

 of having perceived that a direct experiment was needed to prove 

 what so far was only a guess. In an article entitled "Opinions 

 and Conjectures Concerning the Properties and Effects of the Elec- 

 trical Matter, arising from Experiments and Observations made at 

 Philadelphia, 1749," the following passage occurs : — 



*' To determine the question whether the clouds that contain 

 lightning are electrified or not, I would propose an experiment to be 

 tried where it can be done conveniently. On the top of some high 

 tower or steeple place a kind of sentry-box, big enough to contain a 

 man and an electrical stand. From the middle of the stand let an 

 iron rod rise and pass, bending out of the door, and then upright 

 20 feet or 30 feet, pointed very sharp at the end. If the electrical 

 stand be kept clean and dry, a man standing on it, when such clouds 

 are passing low, might be electrified and afford sparks, the rod drawing 

 fire to him from a cloud. 



" If any danger to the man should be apprehended (though I think 

 there would be none), let him stand on the floor of his box, and now 

 and then bring near to the rod the loop of a wire that has one end 

 fastened to the leads, he holding it by a wax handle ; so the sparks, 

 if the rod is electrified, will strike from the rod to the wire, and not 

 affect him." * 



The experiment suggested by Franklin was successfully performed 

 in Marly (France), by D'Alibard, on May 10, 1752,f in London by 

 Canton, in Spital Square, on July 20, 1752, and by Wilson, in 



* 'Experiments and Observations on Electricity made at Philadelphia, in 

 America,' by Benjamin Franklin, LL.D. and F.R.S. ; London, printed for David 

 and Henry, and sold by Francis Newbery, 1769, p. 66. t Ibid., p. 107. 



