208 A. Tanakadate on the Thermal Effect due 



and led to an alternating-commutator through an idio static 

 galvanometer. The alternator was driven by a clockwork. 



IronBXrig 



Mirror 

 GuLT 



Counter 



~Wbi!cleitR.irifj 



It had forty teeth on each side, so that one revolution of it 

 made forty complete reversals of magnetization in the iron 

 ring inside the core. The current was supplied from secondary 

 batteries, and its strength was adjusted by means of resistances, 

 which were in most cases Edison lamps joined in multiple arc. 

 The thermoelectric constant of the junctions was determined 

 by heating the iron ring in a specially prepared sand-bath, 

 while the wooden ring was kept at the temperature of the 

 room. The sand-bath was first heated by a gas-flame up to 

 about 60° C, and left to cool slowly. Several simultaneous 

 readings of the galvanometer-deflexion and temperature- 

 difference of the junctions were taken, and the value of the 

 difference of temperature corresponding to one division of the 

 galvanometer-deflexion was deduced as follows : — 



Determination of Thermoelectric Constant (April 5, 1888). 













Difference of 



Time. 



Temp, of 

 iron ring. 



Temp, of 

 wooden 



ring. 



Difference 

 of tempe- 

 rature. 



Galvanometer- 

 deflexion. 



temperature 

 corresponding 

 to one division 

 of galvano- 

 meter-deflex- 

 ion. 



h m 

 12 



53-6 0. 



14-4 C. 



39-2 0. 



489 



°'0802 C. 



1 5 



42-4 



15-2 



27-2 



343 



•0794 



1 27 



38-8 



151 



23-7 



297 



•0798 



2 



29-6 



15-7 



139 



177 



•0785 



6 



20-8 



14-3 



6-5 



81 

 Mean 



•0801 



•0796 





From the time-rate of the fall of temperature of the iron 

 ring we may judge of the uniformity of temperature inside 

 the sand-bath. The constant was assumed to remain the same 

 till the 20th of the same month, when a sudden change, due 

 to changes in the arrangement of magnets in the laboratory, 

 was observed. The constant was redetermined as follows : — 



