indicates an 

 which that 



e^iy^to^ftelH^icrftM^fthe iridilced wire, 



fehgthening has proAiPM"^^^^ ^^«^^ <'^'" 



61. Two cases might present themselves between the limits 

 of induction, which correspond to zero and to an infinite length 

 of the additional wire, applying the word infinite to that which 

 compels the current to discharge itself wholly by the constant 

 wire. If for constantly increasing lengths we should find the 

 values of the induced current constantly increasing, or inter- 

 mittent values, one while greater, at another less, then only 

 there would be interference in the induced circuit. Now, a 

 multitude of experiments made with the apparatus and wires 

 previously described in § I., and in which the lengthening of 

 the inductor wire is effected by infinitely slow degrees, have 

 shown that the angles of deviation increase without any alter- 

 nation, and have led to the logarithmical laws laid down in 

 § III. There is therefore no interference under the circum- 

 stances in which I have sought to produce it. Mhi\H \ 



62. This result was obtained in November 1841, andcomt- 

 m^micated to the students attending my lectures at the com- 

 mencement of the following year. It might perhaps be ob- 

 jected, that if the induction, whose characteristic it is to be in- 

 stantaneous, is produced by a single wave, it is not certain 

 that the phsenomena of interference are manifested in its de- 

 velopment. This objection would be analogous to that which 

 has been raised against the explanation by electric undula- 

 tions of the remarkable intermittence discovered by Professor 

 De la Rive *, in the conductibility of certain lengths of one and 

 the same metallic wire for magneto-electrical currents sub- 

 mitted to alternative and rapid changes of directionf. With 

 a view to remove all doubt in this respect, I have endeavoured 

 to cause two continuous currents, launched simultaneously in 

 the same wire, to interfere, either in a contrary or in the 

 same direction J. 



ai noi B. Method of Direct and Continuous Currents ^nci ohi 



I '63, The wires which I have used are noted in the foHow- 

 mc Table. They have been chosen quite cylindrical, and 



■'• Memoires de la Societe de Physique et d'Histoire Naturelle de Genhvei 

 vol. ix. See the sequel of these researches in the Archives de r Electricite, 

 vol. i. p. 75, where will be found the explanation of this apparent inter- 



tf^^ikil^tfouri de Physique de VEeole Polytechnique, § 86^ ^^^^"03 1o 

 X M. Peltier has applied the same means, without employing it for the 

 same object, as I have, to graduate thermo-electric rheometers by his method 

 of the sum of tfie united currents, § XXII. of his memoir in the Jnnales de 

 Chimie et de Physique, vol. Ixxi. p. 225. 



