Thermo-electric Couples 



255 



Those readings marked with an asterisk were afterward checked 

 by means of the potentiometer. 



The resistance of this thermo-couple, with its copper leads was 

 .74 ohm, so that, in comparison with the high resistance, *S,it 

 does not need to be taken into consideration. 



Determination of the constants h and c. 



(from the equation E = bt -\- ct~) 



El' = 356 + 1125c = .0011505 

 also El'<^ = 2506 + 62500c = -.01058 



Solving these equations for 6 and c, 



6 .= 31.33 X 10-« 



c = 4.39 X 10-» 



Advance manganin thermo-couple (fig. 11), 

 advance to manganin in the hot junction, 

 at 0. S = 5000 ohms. So (d) = .00004864 v.p. mm. 

 ance of couple, and copper leads, .97 ohm. 



Current goes from 

 Junctions (e) and (g) 

 Resist- 



El^ = 806 + 6400c = .003075 

 ^§25 = 2256 + 50825c = .009220 

 From which equations, 



6 = 29.65 X 10-4 



c = 17.325 X 10-9 



