410 Scientific Intelligence. 
If the force of rotation at each instant be resolved into two compo 
nents, one in the direction of the radius vector, and the other parallel to 
the earth’s orbit, it will be readily perceived that whenever the latter 
tends to increase the aerial pressure, the former tends to diminish it, and 
vice versa. Let s==the height of the barometer at any given instant; 
M=the mean height at the place of observation; -90°==the hour 
angle; c==the earth’s circumference at the equator; ¢—-24 hours; 
g=the terrestrial gravity; 7==the latitude: and a simple integration 
(aes =)" 
R? {2 
gives the theoretical formula, B=M 
This formula gives a maximum height at 9h. and 21h, and a minimum 
at 3h. and 15h. The St. Helena observations place the maximum at 
10h. and 22h, and the minimum at 4h. and 16h,: an hour later in each 
differences an the results of theory and fA But by ta 
the grand mean of a series of sleerrailonk sufficiently extended to 
ance and eliminate set Eppoipel opposing inequalities, the two results 
According to our Pesala, the ae of altitude at 1, 2, and $ 
hours from the mean, should be in the respective ratios of *5; ° $66, 
1. The actual tiference, es ta to the mean of the St. le: 
servations, are as follows 
Differences of Barometer. 
Diff. of time, lh. 2h. sh. lh. 
Before 1h, 0166 0298 0365 “455 
After “ 0159 0266 Uu298 534 
Before 7h 0122 0202 0243 502 
After 0135 0239 0297 “455 
Before 13h. 0136 "0248 0284 479 
After “ 0131 “0215 0227 ‘HTT 
Before 19h. “O161 -0287 0348 +463 
After... #! “0150 0265 “0286 524 
0145 0252 0293 495 
The mean of the above differences varies from the theoretical meaa 
less than zy455 of an inch. If we take the mean of the ratios, instead 
the ratios of m3 means of the observed differences, the coincidence i 
still more stri 
pa of Time, lh. 2h. 3h. 
Means of Observed ratios, 498625 864625 —«:1-000000 
et ae Means, ‘500000 866025 ~—«1000000 
represents the effective ratio of an entire day. But there is in each e 
SE: acceleration, and a half day of retardation, and the ratio for each : 
day is $2 
= gt 
