OF SUNLIGHT THROUGH THE EARTH’S ATMOSPHERE. 
11 
action through clear water 
1 st Exposure j^^tion through turbid water 
2 nd 
3rd 
147 _ 1 
152 ~ 1-037 ’ 
172 _]_ 
181 “ 1-052 ' 
204 _ 1 ^ 
212 ~ 1-055 ’ 
Mean = 
1 
P05 ' 
4-982 
The photographic light passing through the clear water == 4’70 times that 
passing through the turbid water. 
Using the formula I' = le 
log 4-7 = 1-54756 = 1-7/ri 
= -910 for each inch of turbid water. 
The optical measures of the light passing through the clear and turbid cells in the 
w’ o directions were 
3-15 inches clear water, 48-5 ; turbid water, 18-2. 
1-7 „ „ 48-5 ; „ 28-5. 
Taking the measurement of the light passing through the 3-15-inch cell as lying on 
the curve in the formula 1' = 
log 48-5 — log 18-2 = fx X 3-15, 
/X = 311. 
If we take the measure of the 1-7-inch water, w-e have 
log 48-5 — log 28-5 = p, X 1-7, 
p = -313. 
Mean value = -312. 
Now mean value of pj = -9105. Now 
_ A-" _ 105 
Pi p p ’ 
•QOI o 
Ai"^ = - - N = 306-6. 
c 2 
therefore 
