554 POPULAR LECTURES AND ADDRESSES. 



much so that when he discovered the molecular 

 torrent he immediately gave it its true explanation 

 molecules of residual air, or gas, or vapour pro- 

 jected at great velocities 1 by electric repulsion 

 from the negative electrode. This explanation 

 has been repeatedly and strenuously attacked by 

 many other able investigators, but Crookes has 

 defended 2 it, and thoroughly established it by 

 what I believe is irrefragable evidence of experi- 

 ment. Skilful investigation perseveringly continued 

 brought out more and more of wonderful and 

 valuable results : the non-importance of the 

 position of the positive electrode ; the projection 

 of the torrent perpendicularly from the surface of 

 the negative electrode ; its convergence to a focus 

 and divergence thenceforward when the surface is 

 slightly convex ; the slight but perceptible re- 

 pulsion between two parallel torrents due, according 

 to Crookes, to negative electrifications of their 

 constituent molecules ; the change of direction of 



1 Probably, I believe, not greater in any case than two or three 

 kilometres per second. 



2 Address to the Institution of Electrical Engineers, 1891. 



