P. E. Chase on Aerial Tides. 229 
the sun, and we might therefore reasonably expect to find the 
clearest evidences of the relation of temperature to lunar at- 
traction. 
By taking the difference between the successive weekly tides, 
we readily obtain the amount of barometric effect in each quarter. 
The average effect is more than three times as great in the sec- 
ond and third quarters, as in the remaining half month,—a fact 
which suggests interesting inquiries as to the amount of influence 
attributable to varying centrifugal force, solar conjunction, or 
Opposition, temperature, &c. e 
Although, as in the ocean tides, there are two simultaneous 
corresponding waves on opposite sides of the earth, these waves 
are not of equal magnitude, the barometer being uniformly 
higher when the moon is on the inferior meridian, and its at- 
traction is therefore exerted in the same direction as the earth’ 
than when it is on the superior meridian, and the two attractions 
are opposed to each other. : : 
I find, therefore, marked evidences of the same lunar action 
on the atmosphere as on the ocean,—the combination of its at- 
traction with that of the sun producing, both in the air and 
water, spring tides at the syzygies, and neap tides at the quadra- 
tures; and I believe that the most important normal atmospheric 
changes may be explained by the following theory: 
The attraction and rotation-waves, as will be readily seen, 
have generally opposite values, the luni-solar wave being 
Descending, from 0° to 90° *, and from 180° to 270°. 
Ascending, from 90° to 180°, and 270° to 360°. 
_ While a rotation wave is : 
Ascending, from 330° to 60°, and 150° to 240°. 
ic Deccendiny from 60° to 150°, and 240° to 330°. 
From 60° to 90°, and 240° to 270°, both waves are descending 
while from 150° to 180°, and 330° to 360°, both are ascending. 
N consequence of this change of values, besides the principal 
lunar maxima and minima at the syzygies and quay 
there should be secondary maxima and minima at 60° in advance 
those points. : 
The Sine Seited 3 of these theoretical inferences by the St. 
‘Helena observations appears to me to be quite as remarkable 
as that of my primary se _ If we arrange those obser- 
Vations in accordance with the moon’s position, and take the 
Average daily height of the barometer, we obtain the following 
* Counting from either syzygy. 
