DR. DESAGUILIERS. 



489 



the first to electrify running water. Gilbert, of course, 

 had made his rubbed amber attract a water-drop; the 

 Florentine Academy, by like means, had drawn oil up into 

 little viscous strings, and Gray had electrified soap-bubbles; 

 but Desaguiliers found that, when he let water run in a 

 stream out of a copper fountain, he could render the jet 

 electric, so that it would attract thread, by merely holding 

 the rubbed tube above the fountain, and when he applied 

 the tube to the stream, he could draw it sidewise into a 

 curve, or even cause it to fall outside of the vessel placed 

 to receive it. He also appears to have been the first to 

 conceive of atmospheric electricity, and to point out that 

 a cloud or mass of vapor may be an electrified body. He 

 had already recognized that air may be rendered electrical; 

 and supposed it to be made up of electric particles con- 

 stantly repelling one another. He imagined that the air- 

 current which flows along the surface of the ocean is 

 electrical in proportion to the heat of the weather, and 

 that, as he had seen little particles of water leap up in 

 spray to the excited tube, so he conceived the watery par- 

 ticles of the sea to rise to meet the excited air particles, and 

 then, being of the same electricity, to be repelled by them, 

 so that u a cubic inch of vapor is lighter than a cubic inch 

 of air." In the recognition by Hauksbee and Wall and 

 Gray of the similarity of the crackling electric spark to the 

 thunder and lightning, and in this hazy conception of 

 Desaguiliers of electrically-charged clouds and atmosphere, 

 we can now begin to perceive the drift of thought leading 

 toward Franklin's great discovery. 



