[A] The Lycee, No. 36, for January 1st, has a long and rather premature article, in which it endeavours to show anticipations by French philosophers of my researches.  It however mistakes the erroneous results of MM.  Fresnel and Ampere for true ones, and then imagines my true results are like those erroneous ones.  I notice it here, however, for the purpose of doing honour to Fresnel in a much higher degree than would have been merited by a feeble anticipation of the present investigations.  That great philosopher, at the same time with myself and fifty other persons, made experiments which the present paper proves could give no expected result.  He was deceived for the moment, and published his imaginary success; but on more carefully repeating his trials, he could find no proof of their accuracy; and, in the high and pure philosophic desire to remove error as well as discover truth, he recanted his first statement.  The example of Berzelius regarding the first Thorina is another instance of this fine feeling; and as occasions are not rare, it would be to the dignity of science if such examples were more frequently followed.—­February 10th, 1832.

80.  It also appears capable of explaining fully the remarkable phenomena observed by M. Arago between metals and magnets when neither are moving (120.), as well as most of the results obtained by Sir John Herschel, Messrs. Babbage, Harris, and others, in repeating his experiments; accounting at the same time perfectly for what at first appeared inexplicable; namely, the non-action of the same metals and magnets when at rest.  These results, which also afford the readiest means of obtaining electricity from magnetism, I shall now proceed to describe.

S 4. Explication of Arago’s Magnetic Phenomena.

81.  If a plate of copper be revolved close to a magnetic needle, or magnet, suspended in such a way that the latter may rotate in a plane parallel to that of the former, the magnet tends to follow the motion of the plate; or if the magnet be revolved, the plate tends to follow its motion; and the effect is so powerful, that magnets or plates of many pounds weight may be thus carried round.  If the magnet and plate be at rest relative to each other, not the slightest effect, attractive or repulsive, or of any kind, can be observed between them (62.).  This is the phenomenon discovered by M. Arago; and he states that the effect takes place not only with all metals, but with solids, liquids, and even gases, i.e. with all substances (130.).

82.  Mr. Babbage and Sir John Herschel, on conjointly repeating the experiments in this country[A], could obtain the effects only with the metals, and with carbon in a peculiar state (from gas retorts), i.e. only with excellent conductors of electricity.  They refer the effect to magnetism induced in the plate by the magnet; the pole of the latter causing an opposite pole in the nearest part of the plate,