154 Royal Society : — 



Photographs of the spectra of Sirius and Capella were taken upon 

 collodion ; but though tolerably sharp, the apparatus employed was 

 not sufficiently perfect to afford any indication of lines in the photo- 

 graph. 



In the concluding portion of their paper, the authors apply the 

 facts observed to an explanation of the colours of the stars. They 

 consider that the difference of colour is to be sought in the difference 

 of the constitution of the investing stellar atmospheres, which act 

 by absorbing particular portions of the light emitted by the incan- 

 descent solid or liquid photosphere, the light of which in each case 

 they suppose to be the same in quality originally, as it seems to be 

 independent of the chemical nature of its constituents, so far as ob- 

 servation of the various solid and liquid elementary bodies, when 

 rendered incandescent by terrestrial means, appears to indicate. 



June 16. — Major-General Sabine, President, in the Chair. 



The following communications were read : — 



"Aerial Tides." By Pliny Earle Chase, A.M., S.P.A.S. 



The remarkable coincidence which I have pointed out* between 

 the theoretical effects of rotation and the results of barometrical 

 observations, has led me to extend my researches with a view of 

 defining more precisely some of the most important effects of lunar 

 action on the atmosphere. The popular belief in the influence of the 

 moon on the weather, which antedates all historical records, has 

 received at various times a certain degree of philosophical sanction. 

 Herschel and others have attempted partially to formulate that influ- 

 ence by empirical laws, but the actual character of the lunar wave 

 that is daily rolled over our heads, appears never to have been inves- 

 tigated. 



Major-General Sabine has shown that the moon produces a diurnal 

 variation of the barometer, amounting to about "006 of an inch at 

 St. Helena, which is nearly equivalent to y\j of the average daily varia- 

 tion (Phil. Trans. 1847, Art. V.). This would indicate a tidal wave 

 of rather more than 1 ft. for each mile that we ascend above the 

 earth's surface, or from 3 to 6 ft. near the summits of the principal 

 mountain-chains. It is easy to believe that the rolling of such a wave 

 over the broken surface of the earth may exert a very important 

 influence on the atmospheric and magnetic currents, the deposition of 

 moisture, and other meteorological phenomena. As the height of the 

 wave varies with the changing phases of the moonf, its effects must 

 likewise vary in accordance with mathematical laws, the proper study 

 of which must evidently form an important branch of meteorological 

 science. 



Besides this daily wave, there appears to be a much larger, but 

 hitherto undetected, weekly wave. M. FlangerguesJ, an astronomer 

 at Viviers in France, extended his researches through a whole lunar 

 cycle, from Oct. 19, 1808 to Oct. 18, 1827, and he inferred from his 

 observations — 



* See Proceedings of Amer. Philos. Soc. vol. ix. p. 283. 



t The height at St. Helena appears to fluctuate between about '9 and 1-6 ft." 



X Bib. Univ., Dec. 1827. 



