Determination of e, N, and Related Constants. 15 



e 

 in (1), after introducing Bucherer's value of — , viz. 



1-767 x 10 7 , we obtain for the Rydberg constant, 3'294 x 10 15 , 

 which agrees within one-tenth per cent, with the observed 

 value. This agreement constitutes most extraordinary 

 justification of Bohr's equation, and warrants the use of 

 spectroscopic data, combined with the foregoing data on £, 

 for a most exact evaluation of h. The value of h computed 

 thus from (5) with the aid of my value of e and the fore- 



e 

 going value of — , which is now known with a precision of 



one-tenth per cent., is 



h = 6-547 xl5" 27 ± 'Oil. 



It will be seen that the uncertainty is just | the un- 

 certainty in e, since e appears in (5) in a power J that of h, 



e 

 while — affects h by an amount which is ne^lioible in com- 



m J ° ° 



parison. The foregoing value of h may be considered the. 

 most reliable thus far obtainable, its uncertainty being one part 

 in six hundred. It will be seen, too, that it agrees within 

 just one part in five hundred with the value obtained for my 

 sodium curves, which I estimated correct to only one part in 

 two hundred. 



Having thus fixed the value of h to one part in six 

 hundred, we may obtain from Planck's equation the Wien 

 constant, C 2 , with the same precision, for it will be re- 

 called* that 



n _ ILL _ 



^2 — ~r — 



lie _ 6-547 xlQ - 27 x 2-999 xlO 10 

 k~~ 1-372 xlO- 16 



= 1-4312 ±'0030 cm. degrees. 



The estimated error set down above is obtained from the 

 assumption of an uncertainty of one part in six hundred for h 

 and one part in one thousand for k. The latest experimental 

 result on C 2 given out by the Reichsanstalt | is 2 = 14300. 

 Coblentz { gives as the result of his direct experiments 

 2 = 1*4369, while his combination of total radiation experi- 

 ment and theory lead him to C 2 = 1'4322. 



* Phys. Rev. ii. p. 142 (1913). 

 t Ann. Phys. xhiii. p. 430 (1915). 

 t Phys. Rev. vii. p. 094 (1916). 



