16 Prof. R. A. Millikan on a new 



Again, from Planck's equation, 



we can compute the Stefan-Boltzmann constant of total 

 radiation a or cr = — and obtain a result which is uncertain 

 by but six-tenths per cent. The result is 



<t = 5-72xl0- 12 + -034 watt cm." 2 deg." 4 . 



This is exactly the value found by Ooblentz from his most 

 recent and most thorough experimental work * on a. The 

 exceedingly close agreement between all these values of 

 h, C 2 , and cr, computed on the one hand from the work on e r 

 and directly observed on the other, is an indication of the 

 exactness of the work on e. 



The grating spacing in calcite computed f from the 

 foregoing value of e is 3*030 A. 



A summary of the most important constants the values of 

 which are fixed by this determination of e is given below,, 

 with the uncertainty attaching to each : — 



The electron e = 4774 + '005xl0- 10 . 



The Avogadro constant N = 6-062 +-006X10 23 . 



N 0° C er 76 f cm M m ° leCUleS Per °' C ' at | » = 2 -705 +-OQ3xlO» 



Kinetic energy of translation of a I E 5>621 + . 006 xl0 -i4. 

 molecule at 0° C \ ° — 



Change of translational molecular I g _ 2-058 +-002xl0 _ie 

 energy per degree C ( — 



Mass of an atom of hydrogen in grams . m = TG62 +-002 X 10 ~ 24 . 



Planck's element of action h = 6'547 +-011 X 10 ~ 27 . 



Wien's constant of spectral radiation. . c 2 = l - 4312+"0030. 



Stefan-Boltzmann constant of total) ^ _ 5.72 +•034. 

 radiation f 



o 



Grating spacing in calcite d = 3*030 +*001 A. 



I have to express my hearty thanks to Dr. Yoshio Ishida 

 for invaluable aid both in observing and in computing the 

 accompanying data. 



Eyerson Physical Laboratory, 

 University of Chicago, 

 January 12th, 1917. 



* Phys. Kev. vii. p. 694 (1916). 



t Webster, Phys. Rev. vii. p. 607 (1916). 



