292 WRITINGS OF JOSEPH HENRY. [1850 



it would attract the lightning from the heavens, and though 

 the building might be protected by good conductors from 

 the lantern to the earth, 3'et no protection which the pres- 

 ent state of science could devise would be as safe as no 

 exposure ; the very idea of protection involving that of a 

 less degree of danger. Though in the case of the ordinary 

 lightning-rod the lightning is seldom or never attracted 

 from the cloud by the conductor, yet in this case the great 

 height of the mast, the height of the dome above the ground, 

 and the elevated position of the building itself, gave a total 

 elevation bearing a considerable ratio to the height of the 

 cloud : add to this, the' great amount of metallic surface, 

 and, above all, the large gas burner, and we have an 

 arrangement well calculated to elicit a discharge from the 

 cloud, when under ordinary influences no effect of the kind 

 would take place. It is well known to the Section that 

 the best apparatus for collecting atmospheric electricity is a 

 long pole, with a wire along it, and a lantern at the upper 

 end. The fixture on the Capitol was indeed an exploring 

 apparatus on a magnificent scale. The result was such 

 as had been anticipated. The first thunder-storm which 

 passed over the city after the erection of the lantern, dis- 

 charged itself upon it, put out the light, and when the 

 whole was taken down, several perforations were found 

 melted in the copper ball which surmounted the lantern. 



In this case the induction from the cloud took place over 

 the whole surface of the lantern, and the attraction was in 

 proportion to the number of particles in the surface of the 

 metal. The principal action was however due to the stream 

 of heated air from the burning gas. - - - 



[Professor Olmstead mentioned the case of several inverted 

 tin pans placed in a straight line on a bench in the path of 

 the electric discharge, and that they were perforated on op- 

 posite sides as if by a bullet.] 



Professor Henry thought the phenomenon was in accord- 

 ance with known electrical action. If a number of conduc- 

 tors are placed in succession in the path of a discharge, the 

 end of the first, to which the lightning is passing, will be- 



