1864 1 



433 



[Chase. 



able presumption that there maybe lunar-monthly magnetic tides, some- 

 what analogous to those which I have pointed out in the barometer. 

 (Pi'oceedings of the Koy. Soc, June 16, and Am. Phil. Soc, June 

 17, 1864.)'' 



Besides the diflPerentiul or tidal action of the moon, there is a slight 

 tendency to diminish the weight of the air that is nearest the moon, 

 and to increase the weight of that which is most remote. In pro- 

 portion as this tendency is exerted in conjunction with or in opposi- 

 tion to that of the sun, the mean solar-diurnal magnetic currents 

 should be increased or diminished. Slight as the disturbing influence 

 is, and modified as it must be by various causes, both occasional and 

 periodic (e. g. the earth's rotation, the cyclical revolution and con- 

 sequent varying latitude of the moon at the commencement of each 

 new month, the oscillations in the aerial rotation-spheroid produced 

 by lunar attraction, the changes in the average temperature of day 



TABLE I. 



Solar and Lunar Daily Magnetic Tides, in parts of Force.'* 



* The first decimal figures are placed, for convenience, in an upper line. 

 VOL. IX. — 3f 



