Magnets on Mobile Conductors of Currents. 509 



the pole of the magnet, it is subjected to a force of rotation 

 around its own axis, which, becoming greater as it approaches 

 the magnet-pole, produces a twisted appearance in the vein. 

 The sense of the twist depends upon the polarity of the mag- 

 net and the direction of the current, the spiral path being 

 compounded of a rectilinear translation in the direction of the 

 liquid current, and of a rotation in the same sense as the 

 hypothetical Amperian currents, or in the opposed sense, ac- 

 cording to the sense of the electric current traversing the vein 

 (figs. 3 and 4, Plate XIV.). 



The author also attempted to observe the effects produced 

 by powerful magnets upon electrified liquid jets which broke 

 into drops in the air. Here no current proper could traverse 

 the vein ; and the electromagnetic effects of the electric con- 

 vection of the falling drops was so small as to be unappreci- 

 able with the apparatus at his disposal. 



Since, however, Eowland * has demonstrated that the me- 

 chanical motion in space of a charged insulated conductor 

 may affect a magnet, there appears to be every reason to 

 conclude that an electrified liquid jet should obey the same 

 electrodynamic laws as a conductor carrying a current. In- 

 deed the experiments of Mr. Crookes, cited above, prove the 

 analogy to be true in the converse case of the flights of mole- 

 cules in the ultra-gaseous atmospheres of his exhausted tubes. 



So far as the author is aware, there has not yet been made 

 any attempt to apply the same reasonings to the electric con- 

 vection-streams of the brush-discharge. He ventures to 

 predict that the brush-discharge from a fine point, when 

 taking place at the pole of a powerful magnet, will be found 

 to be subjected to a similar torsion, and to appear spiral in 

 form. 



There are recorded in the i Philosophical Magazine ' for 

 1849 and 1850 some curious researches by Mr. Reuben 

 Phillips on the magnetic behaviour of jets of steam, which are 

 of interest as bearing upon the subject under discussion. 



The author has reason to think that the phenomena described 

 in that memoir, and also the much better-known phenomena 

 of the so-called diamagnetism of flames and of smoke-jets, 

 are also only further instances of the magnetic behaviour ot 

 electric convection-currents. As, however, this matter will 

 form the subject of a separate research, the author reserves 

 such observations as he might offer on these points for another 

 occasion. 



* Phil. Mag. 1876. 



