Page:Philosophical Transactions of the Royal Society A - Volume 184.djvu/20

20 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 :182. Similarly, with the barometer at 19-9, it was calculated to be .196.

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 26 25 423 394 .367 340 314 289 97 .266 9 24 23 22 21 .244 222 201 182 20 19
 * 453

It will be seen that the coefficients obtained on these exceptionally clear days fall extremely close to the calculated values. The calculation for

24.4 is 299, 29.6 is 441, 23.4 is 276, 26.6 is 356, 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 :-

99 99 30 inches 29 27 26 25 24 23 21.5 509 -477 412 .381 353 325 297 261 9 22 2