1655.  It has been shown by several experimenters, that whilst the discharge is of the same kind the amount of lateral or magnetic force is very constant (216. 366. 367. 368. 376.).  But when we wish to compare discharge of different kinds, for the important purpose of ascertaining whether the same amount of current will in its different forms produce the same amount of transverse action, we find the data very imperfect.  Davy noticed, that when the electric current was passing through an aqueous solution it affected a magnetic needle[A], and Dr. Ritchie says, that the current in the electrolyte is as magnetic as that in a metallic wire[B], and has caused water to revolve round a magnet as a wire carrying the current would revolve.

  [A] Philosophical Transactions, 1821, p. 426.

  [B] Ibid. 1832, p. 294.

1656.  Disruptive discharge produces its magnetic effects:  a strong spark, passed transversely to a steel needle, will magnetise it as well as if the electricity of the spark were conducted by a metallic wire occupying the line of discharge; and Sir H. Davy has shown that the discharge of a voltaic battery in vacuo is affected and has motion given to it by approximated magnets[A].

  [A] Philosophical Transactions, 1821, p. 427.

1657.  Thus the three very different modes of discharge, namely, conduction, electrolyzation, and disruptive discharge, agree in producing the important transverse phenomenon of magnetism.  Whether convection or carrying discharge will produce the same phenomenon has not been determined, and the few experiments I have as yet had time to make do not enable me to answer in the affirmative.

* * * * *

1658.  Having arrived at this point in the consideration of the current and in the endeavour to apply its phenomena as tests of the truth or fallacy of the theory of induction which I have ventured to set forth, I am now very much tempted to indulge in a few speculations respecting its lateral action and its possible connexion with the transverse condition of the lines of ordinary induction (1165, 1304.)[A].  I have long sought and still seek for an effect or condition which shall be to statical electricity what magnetic force is to current electricity (1411.); for as the lines of discharge are associated with a certain transverse effect, so it appeared to me impossible but that the lines of tension or of inductive action, which of necessity precede that discharge, should also have their correspondent transverse condition or effect (951.).

  [A] Refer for further investigations to 1709.—­1736.—­Dec. 1838.