20 
CAPTAIN W. DB W. ABNEY ON THE TRANSMISSION 
place. Thus, at the RifFel house it was calculated that the coefficient at a barometric 
pressure of 21’2 inches, was ’222; and from observations made with the barometer 
at 18’9, it was calculated the coefficient would be T82. Similarly, with the barometer 
at 19‘9, it was calculated to be T96, 
It will be seen, if we take the Faulhorn observations as a standard, that we get 
what appears to be a very close approximation to the law that the exponential 
coefficient varies as the square of the barometric pressure. 
The following is a table calculated on this assumption :— 
30 inches 
29 
28 
} ? 
27 
J5 
26 
?? 
25 
24 
33 
23 
33 
22 
33 
21 
33 
20 
33 
19 
5 3 
•453 
•423 
•394 
•367 
•340 
•314 
•289 
•266 
•244 
•222 
•201 
•182 
It will be seen that the coefficients obtained on these exceptionally clear days fall 
extremely close to the calculated values. The calculation for 
29-6 is 441, 26-6 is 356, 24-4 is 299, 
23-4 is 276, 21-5 is 232. 
On the day when the Faulhorn observation gave a value to the coefficient of ^261, 
the sky was fairly good. If we take this as a starting point and calculate as before, 
we find the following table :— 
30 inches 
29 
27 
26 
25 
24 
23 
21-5 
?5 
•509 
•477 
•412 
•381 
•353 
•325 
•297 
•261 
