P. E. Chase on Barometric Fluctuations. 381 
rotation cannot produce currents, but it modifies them when 
they are produced by the action of heat.” 
here can be no doubt that heat is one of the causes, and in 
most places it is, perhaps, the principal cause, of those atmos- 
pheric disturbances which are modified by rotation, but the as- 
sumption that the atmosphere ‘‘ would be everywhere at rest,” 
oped for differences of temperature, leads to palpable absurd- 
It may be freely admitted that Galileo, in attributing the 
ocean tides exclusively to ‘the rotation of the earth, combined 
with its revolution about the sun,” attached too much importance 
to the simple combination of the motions of rotation and orbital 
translation, but his mistake is no greater than the opposite be- 
lief, which is now too prevalent, that there is only a single in- 
fluence which can produce any important tidal effects in the at- 
mosphere. 
¥ which are functions of the latitude, of gravity, and of time, 
| Subjoin, in illustration, a 
Table of the average daily lunar barometric tides. 
Station. | Station. 
1 pid Siena ne ‘La 
Hours, Pane en are Cee ee : 
St. Helena. Girard College. | St. Helena. Girard College. 
in. i in. i 
0 —-00006 +00313 6.| 00276 -00308 
1 --00051 841 q 00242 00389 
2 —00172 +00291 8 —00121 --00290 
3 00253 +-00214 9 —00046 -"00206 
4 —00315 00011 10 +00021 +°00013 
5 —00330 ~00144 11 +00035 +00149 
The existence of the tidal Jaw, which, as we have seen, should 
ees differences in the respective ratios of “5, ‘866, and 1, at 
, 2, and 3 hours from the mean tide, is shown in the following 
® See Proc. Am. Philos. Soc., ix, 283-4. 
_ * This is evidently only another form of a single element in La Place’s law of the 
_ [present it in this shape, both because I obtained it independently, and be- 
‘tee it makes the resemblance to my rotation formula more striking. 
