14 Prof. E. A. Millikan on 



a new 



Accordingly, the actual records of the observations on all 

 of the 18 starred drops which were chiefly considered in 

 determining the line in fig. 2 are given below. The other 

 seven are omitted merely to save space. As the graph 

 shows, they do not modify in any way the result. With 

 their inclusion the graph becomes the record of 25 con- 

 secutive observations without any discards, so that the result 

 is entirely free from the exercise of choice. 



8. The Values of some other Related Constants. 



I have already recorded in the 1913 paper the values of 

 six fundamental but related constants which are at once 

 known as soon as e is found, and with the same precision as 

 that attained in its evaluation. These six are : (1) the 

 electron, e ; (2) the Avogadro number, N ; (3) the number 

 of molecules, n, in an ideal gas at 0° C. 76 cm. ; (4) the 

 kinetic energy, E 0; of molecular agitation at 0° C. ; (5) the 

 constant change, , in molecular energy per degree ; (6) the 

 entropy constant, k, or the gas constant applied to a single 

 molecule. A seventh constant which should have been 

 included at that time is the mass m of a hydrogen atom, 

 given by 



4-774 xl0- 10 x 1-0077 1 „~ in _ 24 



m = - n/1 , n , -> nnr , — TTrvn — 1 obJ X 10 Zi gram. 



9b49-4x 2*999 x 10 10 fe 



This list may now be extended as follows : — 

 The constant of the Balmer series of hydrogen is known 

 with the great precision attained in all wave-length deter- 

 minations, and has the value 3*290 x 10 15 . From Bohr's 

 theory it is given by 



27T6 4 m 2tT£ 5 , K . 



TT or — r5) 



I have shown that h may be determined photoelectrically* 

 with an error in the case of sodium of no more than 

 ■J per cent., the value given by my work on sodium being 

 6*56 xl0~ 27 . The value found by Webster f by the X-ray 

 method discovered by Duane and Hunt J is 653 X 10~ 27 . 

 Taking the mean of these two results, viz. 6*545 x 10~ 27 , 

 obtained by wholly dissimilar methods, and substituting 



* Phys. Kev. vii. p. 374 (1916). t Ibid. vii. p. 599 (1916). 



t Ibid. vi. p. 166 (1915). 



