44 
Proceedings of the Koyal Society of Edinburgh. 
IV.— On the Transverse Galvanomagnetic and Thermomagnetic 
Effects in several Metals. By F. Unwin, M.Sc. Communicated 
by Professor F. G. Baily. 
(MS. received November 10, 1920. Read January 10, 1921.) 
Introduction. 
In a previous paper * the author has described experiments to determine 
the Hall effect and the two transverse thermomagnetic effects in several 
metals. The fourth transverse effect — namely, the galvanomagnetic tem- 
perature effect — was not measured at that time, as the measuring arrange- 
ment was not sufficiently sensitive for this purpose. 
In the present state of the electron theory of metals the ratios of these 
transverse effects to each other is of very considerable interest, and hence 
it is desirable to have determinations of all four transverse effects. Deter- 
minations have been made by other workers, but, so far as the author is 
aware, only in the case of a few metals. The present paper records the 
determinations for eight different metals — iron, nickel, cobalt, silver, 
copper, zinc, cadmium, aluminium. 
Description of Effects and Definition of Coefficients. 
Galvanomagnetic Effects. 
Suppose a strip of metal, carrying an electric current, to be placed 
between the poles of an electromagnet. When the magnet is excited it is 
found that there are set up between the edges of the plate a difference of 
potential and a difference of temperature. These constitute respectively 
the Hall Effect and the Galvanomagnetic Temperature Effect. The co- 
efficients R and P are the values of these effects in a plate 1 cm. wide 
placed in magnetic field of unit strength when the potential gradient along 
the plate is 1 c.g.s. unit per cm. 
Thermomagnetic Effects. 
If with the above arrangement a heat current is sent along the plate 
instead of the electric current, it is again found that a transverse potential 
difference and a temperature difference are set up. 
These constitute the Thermomagnetic “ Potential Effect ” and “ Tem- 
perature Effect ” respectively, and the coefficients Q and S are the magni- 
tudes of these effects under the standard conditions named, the temperature 
gradient along the plate being one degree Centigrade per cm. 
* Proc. Boy. Soc. Edin ., vol. xxxiv, p. 208 (1914). 
