1864.J 



397 



[Cha.se. 



when the sun is below the horizon, gave such results as I anticipated, 

 as will be seen by a reference to the following 



TABLE OF BAROMETRIC AND THERMOMLTRIC MEANS AT THE MOON's 



CHANOKS. 



In obtaining the above averages I was obliged to interpolate for 

 such changes as took place on Sundays or holidays, when no observa- 

 tions were taken. The interpolation, however, does not affect the 

 general result ; and, on some accounts, the table is more satisfactory 

 than if the observations had been made with special reference to a 

 determination of the lunar influences, accompanied as such a refer- 

 ence would very likely have been by a bias to some particular theory. 



The thermometric and barometric averages show a general corres- 

 pondence in the times of the monthly maxima and minima, — the 

 correspondence being most marked and uniform at midnight, when 

 the air is most removed from the direct heat of the sun, and we 

 might therefore reasonably expect to find the clearest evidences of 

 the relation of temperature to lunar attraction. 



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 ^han three times as great in the second and 

 third quarters, as 'in the remaining half month, — a fact which sug- 

 gests interesting inquiries as to the amount of influence attributable 

 to varying centrifugal force, solar conjunction, or opposition, tempera- 

 ture, &c. 



Although, as in the ocean tides, there are two simultaneous cor- 

 responding 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 attraction is therefore ex- 

 erted in the .same direction as the earth's, 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 



