﻿256 Quantum Theory of Photographic Exposure. 



Number of 





N.10" 3 per 



£.]0~ 3 per 







2 



sq. cm. 1 grain 



sq. cm. 1 grain 



k 



in Clump. 



P • 



layer plate 



layer plate 



W 





(original). 



(developed). 





1 



0-75 4 



65770 



1086-0 



0*165 



2 



1-92 5 



1322-0 



594-0 



0-449 



3 



3-03 



664-0 



508-6 



0-766 



4 



4-88 1 



328-0 



2863 



0871 



5 



-r.^ 9 i unreliable 



249 9 

 157-8 



240-0 

 155-0 



0-960 

 0-982 



6 



7 



8-6 



1052 



105-2 



1-000 



8 



9-8 

 110 



526 



52-6 



52-6 



52-6 



1-000 

 1-000 



9 



10 



120 



39-5 



39-3 



1000 



11 





26-3 

 39-5 



26-3 

 39-5 



1-000 

 1-000 



'2 



13 





19-8 



19-8 



6-5 



13-2 



13-2 



132 



6-5 



3-3 



198 



19-8 



66 



132 



132 



6-5 



3-3 



G-6 



1-000 

 1-000 

 1000 

 1-000 

 1-000 

 1-000 

 1-000 

 1-000 



14 



15 



16 



17 



18 



19 



20 



21 





6-6 

 13-2 



13-2 

 33 



1-000 

 1-030 



22 



23 





3-3 



1-3 



1-000 



24 





1<3 



6-6 



1-000 



25 





66 



1-3 



1000 ■ 



26 





1-3 







1-000 



27 









33 



1-000 



28 





3-3 







1-000 



29 













1-000 



30 









1-3 



1-000 



31 





1-3 



1-3 



1-000 



32 



24-0 



1-3 



1-3 



1-000 



33 



25-0 



1-3 





1-000 



The agreement of the numbers of the last column with 

 those calculated by Silberstein's formula (with N = 0*572 

 and <r = 0*0973), as given in his paper, is manifestly a very 

 pronounced one. The differences between the observed and 

 calculated values are even in the case of the 3 grain clumps 

 entirely within the limits of experimental error, particularly 

 concerning the area measurements. 



In continuance of this work the theoretical formula will 

 be subject to further tests, the results of which will be 

 published shortly. 



Rochester, N.Y. 



January 24, 1922. 



