118 



while it is revolving from the eastern extremity round the unmarked 

 pole to the western extremity of the axis minor, the current of elec- 

 tricity will be from the upper to the lower end of the wire; and 

 whatever position the plane in which the wire revolves may take by 

 revolving about the axis of the magnet, or whatever may be the po- 

 sition of this axis, still the current of electricity will be from the end 

 of the wire in the same position, relatively to the plane of revolution, 

 as before. If the direction of the motion be reversed, the direction 

 of the current will likewise be reversed. 



It would follow from this, that if two wires parallel to each other, 

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

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

 rents of electricity in them will be 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 

 phaenomena observed in these experiments and in those by Mr. 

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

 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- 



