294 PROCEEDINGS OF THE AMERICAN ACADEMY. 



We have : — 



h = the thermal conductivity in c. G. s. units. 



Q = number of heat units flowing through disk in one second ; 



T = thickness, in centimeters, of the steel disk ; 



S = area, in square centimeters, of horizontal cross-section of the 



steel disk ; 

 t = mean difference in temperature of sides of steel disk ; 

 m =z mass, in grams, of water traversing upper chamber per second ; 

 Ai = mean deflection in circuit 1, as before described; 

 Ag = mean deflection in circuit 2, in conduction test; 

 Jij^ = reduction factor of galvanometer 1 ; 

 ^2 = reduction factor of galvanometer 2 ; 

 di = mean deflection of galvanometer 1 in sensitiveness test ; 

 do = mean deflection of galvanometer 2 in sensitiveness test ; 

 [i?i X c?! = -ff 2 X c?2j and so Rx -=r R« ^= d^ ■— d(\ ; 

 Ex = e. m. f., in volts, of copper-steel element per 1° C. difference of 



temperature ; 

 ^2 = 6. m. f., in volts, of copper-German-silver element per 1° C. 



difference of temperature ; 

 Vx = resistance, in legal ohms, of circuit 1 in conduction test ; 

 To = resistance, in legal ohms, of circuit 2 in conduction test ; 



Then 



Ao X i?o X ?-o 



Sxt A, X 7?i X rx 



^^ £x 



„ R. To Ex\ T 

 = I «^ X ^ X ^ X ^- X ^ J X -. 



( ^2 



Using this formula with the data for series A and B of September 2, 

 we have : — 



