INORGANIC RESPONSE 161 
the incandescent burner is at a distance of 150 cm., has 
been taken as the arbitrary unit. In order to make 
allowance for the possible effects of fatigue I took two 
‘ 
‘ 
i ’ 
‘ ‘ H 
‘ ‘ ' 
' J ' 
. . ' 
4 1 
. H 
H H 
H 1 
‘ 
i! ' nl 
7 . . ' 
+ ° ‘ ‘ 
" ‘ 7 ‘ 
A ‘ 4 H 
; : ‘ H 
' ‘ ; ‘ ‘ 
H 4 ; ‘ ' 
i ; ' 
‘ * ‘ i 1 
4 ‘ ' 4 ‘ 
' ‘ ‘ ‘ ' 
H H H ‘ ‘ 
- : : ’ H ‘ 
‘ : r H H . 
. ' 7 ' nN 
‘ i : ' ‘ 
‘ , : : H ‘ 3 
‘ ; : : 1 4 ‘ 
‘ ; ‘ H t 
‘ ‘ ‘ . H H 
4 ‘ . ‘ 
“ ‘ i ' . ‘ . ‘ 
s 4 N F ’ ’ ’ . 
; \ ’ H ‘ ’ i‘ ‘ 
‘ 2 . Hy H ‘ 4 ‘ 
‘ ’, “ 2 ‘ ‘ ‘ ‘ 
NS: +; BS rm ‘ \ ‘ ‘ 
= e oy ’ . . 
Bay ‘ , . 
. see 
5 3 1 ‘ 
‘ 
. 
. 
7 

Fic. 103.—Responses or Sensitive Cent to various INTENSITIES OF LicuT 
On the left the responses are for diminishing intensities in the ratios of 7, 5, 3, 
and 1. On the right they are for the increasing intensities 1, 3, 5, and 7. 
The thick lines are records during exposures of one minute; the dotted 
lines represent recoveries for one minute. 
successive series of responses (fig. 103). In the first, 
records were taken with intensities diminishing from 
7 to 1, and immediately afterwards increasing from | to 
7, in the second. 
TABLE GIVING RESPONSE TO VARYING INTENSITIES OF LIGHT 
(The intensity of an incandescent gas-burner at a distance of 150 cm. 
is taken as unit. ) 

Response Response 






ad _ (Light _ (Light Mean Value in volt 
diminishing) } increasing) 
i 43 3 41 63-0 x10- volt | 
5 31 29 30 46:1 x 2 
/ 3 18°5 17:5 18 204 x - 
eee | 10 9 9-5 146x ,, | 



As the zero point was slightly shifted during the 
M 
