TILE 
LONDON, EDINBURGH ann DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[FOURTH SERIES.] 
FEBRUARY 1861. 
XII. Note respecting Ampére’s Experiment on the Repulsion of 
a Rectilinear Klectrical Current on itself. By James D. 
Forses, D.C.L., V.P.R.S.E., Principal of the United College, 
St. Andrews, late Pr ofessor of Natural Philosophy in the Uni- 
versity of Edinburgh*. 
[With a Plate. ] 
p a communication to the Royal Society of Edinburgh, on 
the 3rd of January, 1859, I related some experiments on 
the vibrations of metallic bodies and of carbon, produced by the 
passage of electricity through them+. I learned soon after, 
from a paper by Dr. Tyndall{, that these vibrations had been 
already described by Dr. Page of the United States§. The 
analogy of the experiment to that of Mr. Trevelyan, on the 
vibrations of metallic bodies by heat, led me to suspect that the 
resistance to the propagation of heat in the first case, and of 
electricity in the second, in its passage from the one to the 
other of the bodies in contact, was the cause of a sensible me- 
chanical repulsion. So strongly was I persuaded of this, that 
twenty-seven- years ago, when making my experiments on the 
“Trevelyan” bars, I attempted to set them in motion by elec- 
tricity, though then ineffectually. 
[Tam aware that the idea of the idio-repulsive quality of the 
heat-current has not been favourably received, and that the high 
authority of Mr. Faraday is still given for an explanation of the 
* Communicated by the Author, having been read to the Royal Society 
of Edinburgh, January 7, 1861. 
t Proceedings of the Royal Society of Edinburgh, vol. iv. p. 151; and 
Phil. Mag. vol. xvii. p- 308. 
is Phil. Mag. vol. xvi. p. 358. 
§ Silliman’s Journal (1850), vol. ix. p. 105. 
Phil. Mag. 8, 4. Vol. 21. No. 188, Fed, 1861. G 
