Chase.] 



;98 



[June. 



the atmosphere as on the ocean, — the combination of its attraction 

 with that of the sun producing both in the air and water, spring 

 tides at the syzj'gies, and neap tides at the quadratures ; and I be- 

 lieve 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 lunisolar wave being 



Descending, from 0° to 90°,* and from 180° to 270^ 

 Ascending^ from 90° to 180°, and 270^ to 360°. 



While the rotation-wave is 



Ascending, from 330° to 00°, and 150° to 240°. 

 Descending, from 00° 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 3G0°, both are ascending. 

 In consequence of this change of values, besides the principal lunar 

 maxima and minima at the syzygies and quadratures, there should 

 be secondary maxima and minima at 60° in advance of those points. 



The confirmation of the.^e theoretical inferences by the St. Helena 

 observations appears to me to be ([uite as remarkable as that of my 

 primary hypothesis If we arrange those observations in accordance 

 with tlie moon's position, and take the average daily height of the 

 barometer, we obtain the following 



TABLE OF THE LUNAR BAROMETRIC TIDES. 



* Counting from either syzygy. 



t Since the tabular numbers represent the semi-nres of the barometric curv( 

 and not the simple ordinaUs, the A-alues for 0" and 180'^ are the same. 



