528 Mr. H. Tomlinson. The Influence of 



Table II. 



Metal. 



" Rota- 

 tional co- 

 efficient."* 



Direction 

 of thermo- 

 electric 

 current.f 



Alteration of 

 specific resistance 

 per unit divided by- 

 increase of length, 

 per unit. J 



Ditto. 

 -1*613 





+ 78*0 



+ 



+ 2*618 



+ 1 * 005 







+ 



+ 2 • 082 



+ 0*469 





+ 25 '0 



— 



— 2*203 



— 3 *816 





+ lo U 



+ 



■ n. no 

 + £i llO 



+ U OUU 













+ 1*613 









— V 4 





+ 1 * 630 



i f\ . A1 17 

 + U 01/ 





— 1 "3 





+ 0*166 



— 1*447 





— 2*4 





+ 2*239 



+ 1 * 626 





— 6'8 











- 8-6 



- 



+ 1*617 



+ 0*004 





— 10*0 





+ 1*005 



— 0*382 





- 50-0 



+ 



-0*420 



- 2*033 





- 50-0 





-0*733 



- 2*346 





-120-0 





-8*860 



-10 -473 



German-silver . . . 







+ 0*226 



- 1*387 



Platinum-silver. . . 







+ 0*624 



- 0-989 



Platinum-iridium . 







+ 4*486 



+ 2-873 



observation to which, the numbers in this column are liable to be 

 affected, the signs are here the same as those in the second column. 



As regards the relationship between the alteration of specific 

 resistance by traction and that of the thermo-electric qualities of the 

 metals due to the same cause, it may be seen by comparing the third 

 and fifth columns, that out of sixteen different metals, pure and alloyed, 

 the signs in the two columns are decidedly the same in eleven instances, 

 are decidedly different in three instances, and are dubiously so in two 

 instances. 



It has been noticed § that if the density of a substance be denoted 

 by A, and A represent the atomic mass, so that the difference between 



the centres of adjacent molecules be proportional to 



my possession, the effect of traction on the thermo-electric properties of the metal 

 seemed to be the same in direction as that given, and for which Bidwell is my 

 authority, but the effect was very slight, and I am not now quite certain whether a 

 less stress than was then applied would not give an opposite result. 



* A + sign in this column signifies that the effect is in a direction the same as 

 that which the conductor itself bearing the current would follow if free to move 

 across the lines of magnetic force (see " Nature," Nov. 10, 1881, p. 46). 



f A + sign in this column signifies that the direction of the thermo-electric 

 current is from unstretched to stretched through the hot junction. 



X A + sign in this column signifies increase of resistance. 



§ Loc. cit. y p. 32. 



