NO. II USK OF TIIK PYUANOMKTFU AlJJJOT AND ALDRICII 7 



From these experiments it appears that when proper allowance is 



made for non-uniformity of the sensitiveness of the ^galvanometer 



scale, the deflection observed is exactly proportional to the square 



of the strength of the heating current applied to the pyranometer. 



Hence it follows that if a certain current C\ produces a deflection /^,. 



and a certain radiation R produces a slightly different deflection D.., 



the radiation R would he exactly compensated by a current C„ such 



C 2 D 

 that ^2 = w'. IMiis valuable result enal)les us to dispense witli the 



tedious process of producing exact compensations. 



On the method of observing in daytime ivith the pyranumeter as 

 illustrated by sample observations on Mount Wilson. 



August 7, 1916 



Object 



Sky . 



Current 



Sky 



Current 



Sun and sky. 



Current 



Sun and .sky. 

 Current 



Current 

 (O . 



amperes 



C« 



He 



.0497 



• -'31 



.607 



.0171 



.0534 .0167 

 .368 . 0709 



.610 



.372 .of)!)! 



Calo- 

 rics 



0.137 



0.140 



I .240 



On the method of observing at night with the pyranometer as 

 illustrated by sample observations on Mount Wilson. 



Note.— Quite windy, but the galvanometer remained steady 

 when balance was reached. 



