6(S jRo}^al Society. 



on opposite sides of a bar magnet, and perpendicular to its axis, bfe 

 moved along the sides of the magnet in the same direction, the cur- 

 rents of electricity in them will he in opposite directions; and hence 

 we may draw this important conclusion, — that there must be some in- 

 ternal arrangement in a magnet, whether of currents or of particles, 

 which renders the same absolute motion, a motion in contrary direc- 

 tions relatively to such arrangement on the opposite sides of the 

 magnet. 



From all these experiments the author concludes, that when a 

 piece of metal (and the same may be true of all conducting matter,) 

 is passed either before a single pole, or between the opposite poles 

 of a magnet, electric currents are produced across the metal, trans- 

 verse to the direction of motion ; and which therefore in M. Arago's 

 experiments approximate towards the direction of radii. Assuming 

 the existence of these currents, he satisfactorily accounts for the 

 phfenomena observed in these experiments and in those by Mr. 

 Babbage and Sir John Herschel. Thus, the disc revolving in tho 

 direction of the sun's daily motion beneath the marked pole of a 

 magnet, currents of positive electricity set from the central part to- 

 wards the circumference near the pole, and the action of these cur- 

 rents is to move the pole also in the direction of the sun's motion ; 

 so that the magnet, if at liberty to revolve, will move in the same 

 direction as the disc. 



Electric currents similar to those produced by passing copper be- 

 tween the magnetic poles, were produced by iron, zinc, tin, lead, 

 mercury, and all the metals tried. The carbon deposited in the coal- 

 gas retorts also produced the current, but ordinary charcoal did 

 not ; nor could any sensible effects be produced with brine, sulphu- 

 ric acid, or saline solutions. Although the author succeeded in ob- 

 taining a continuous current of electricity by means of the revolving 

 disc, yet he was not able, by this means, to produce any sensation 

 upon the tongue, to heat fine platina wire, to produce a spark with 

 charcoal, to convulse the limbs of a frog, or to produce any chemical 

 effects. That he should have failed in obtaining these most striking 

 effects of electricity, we attribute to the feebleness of the electricity 

 excited, and feel assured that by adopting means greatly to increase 

 the intensity, all these effects will result from the electricity derived 

 from ordinary magnetism. 



The facts contained in this paper of Mr. Faraday's, and the con- 

 clusions which he draws from them are so important, that we feel we 

 should not have done justice to the communication, had we not given 

 an abstract of the whole, at the same time that we stated our opi- 

 nion of its value. Had the author's discovery consisted alone of the 

 simple fact, that steel may be magnetised by a distant magnet, in a 

 manner similar to that employed with the voltaic battery, we should 

 have considered it of the highest importance in the inquiry concerning 

 the connexion between magnetism and electricity ; but when we see 

 permanent effects which, hitherto, have only been derived from 

 electricity, now derived from the common magnet, by calling in the 

 aid of motion, showing clearly that electricity can thus be excited ; 



