588 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE VI. 



August 16. Energy Measdrements. Through Air. Series 4. 



Zero of Galvanometer G l (closed circuit) determined by method of cooling 

 = 216 8 = reading at room temperature. 



observations were made on each face of the disc. The black coating was 

 always cleaned off from the face of the disc away from the light. All of 

 the series of energy measurements are gathered together in Tables VII 

 and VIII. In the tables, under the head " through air," the first column 

 contains the observed rate of increase in the galvanometer deflection G u 

 when the disc and its surroundings were at the same temperature ; the 

 second column, the corresponding mean lamp deflections of galvanometer 

 Go. The third and fourth columns contain the sensitiveness of galva- 

 nometers G l and G 2 respectively, and the last column the values of the 

 first column reduced to standard lamp and standard sensitiveness of both 

 instruments. The series on the two faces of the disc are recorded and 

 averaged separately, then combined with their probable errors in the 

 general average at the end of Table VIII. 



Tables VII and VIII give the following results. The average increase 

 in the reading of G x for standard conditions is 0.96G mm. per second. 

 From the thermal calibration, a deflection of 9.96 divisions corresponds 



