The Thermo-electric Effects of Longitu- 

 dinal Stress in Iron. 



By 



K. Tsuruta, Rigakushi. 



Assist. Prof, of Physics, Science College, 

 Imperial University. 



With Plates I— III. 



§ 1. The foundation of our knowledge of the thermo-electric 

 effects of stresses in iron and other metals was laid by Lord Kelvin, 

 who in his Bukerian Lecture of 1856 on "Thermo- dynamic Qualities 

 of Metals " (i) made it generally known that metals subjected to stress- 

 es, temporarily or otherwise, are thermo-electrically different from 

 those which are not so affected. Another fact, which was established, 

 is that " in general, metals subjected to stresses not equal in all direc- 

 tions will acquire the crystalline characteristic of having different 

 qualities, as regards thermo-electricity, in different directions." These 

 facts were demonstrated by various experiments which are described 

 in § 105-133 of his paper. 



§ 2. A distinct step of progress in the study of the subject was 

 made through the work of Dr. Cohn (2) and of Prof. Ewing. (3) We owe 

 to them the discovery that in iron, which shows the thermo-electric 

 effects of longitudinal tension in a very striking manner, there is an 



(1) Math, and Phys. Papers, vol. 2. Art. XI. 



(2) Wiecl. Annalen. Bd. VI. 



(3) Phil. Transactions. 1886. 



