308 Sir W. de W. Abney. On the Variation in 



Table IV. Table V. 



Amyl- acetate scale. 



Exposure in 



Beading of 



powers of 2. 



.Annulus. 



1 



202 



. 2 



189 



3 



168 



4 



145 



5 



122 



6 



98 



7 



77 . 



8 



55 



Bare glass 



21 



" Star " opacities. 



Intensity in 



r? PQflm IT C\\ 

 XvCctlli 11 g KjL 



powers of 2. 



flTimiln a 



tXLLlL lA.LH.Tf, 







202 



A .90 



V 66 



197 



065 



187 



"93 



178 



1-50 



156 



2*05 



136 



3 05 



97 



362 



77 



4-61 



39 



5-22 



30 



6-13 



26 



7-74 





Bare glass 



21 



Fig. 4. 



1 1 1 1 )225 



Time of exposure for AmyL-AceC&Ge L&mp in powers of-£. 



