206 Royal 'Society. 



painful illness occasioned by an internal disease. The histoi'y of 

 his labours will occupy a large and prominent place in the history 

 of astronomy durini^ the first half of tlie present century. 



The Baron de Damoiseau was one of the most distinguished 

 astronomers of tlie age. His most considerable work was his " Me- 

 moire sur la Thcorie de la Lune," wiiich was presented to the In- 

 stitute in 1821, but not published before 1827, when it appeared in 

 the " INIemoires des Savans Etrangers." The methods which are used 

 in this important memoir are, generally speaking, the same as those 

 adopted by Laplace : the moon's true longitude being assumed as 

 the independent variable, and the final equations solved by the me- 

 thod of indeterminate coefficients ; the solutions being given in nu- 

 merical and not in literal coefficients, as in the great work of Plana 

 on the same subject. The approximations, also, are carried to a 

 greater extent than in the " Mecanique Celeste." This memoir was 

 followed by the celebrated "Tables of tiie Moon," which were founded 

 upon it, and which appeared in 182i imder the title " Tables de la 

 Lune, formee sur la seule Theorie de I'Attraction et suivant la divi- 

 sion du cercle en 400 degres." They form the first, and indeed the 

 only expanded tables of the moon which are founded entirely upon 

 theory, borrowing nothing whatever from observation but the sim- 

 ple elliptic elements, the proportion of distances of the sun and moon, 

 and the masses. All preceding tables, such as Mayer's, Borg's and 

 Burckhardt's, had derived many of their coefficients empirically from 

 observation. These tables are the basis of those which are used by 

 the present Astronomer Royal in the great lunar reductions which 

 are now in progress under his superintendence. 



The Baron de Damoiseau was also the author of " Tables of the 

 Satellites of Jupiter," and of many other works and memoirs con- 

 nected with the advancement of astronomical science : he was a very 

 profound analyst, a most laborious and faithful calculator, and the 

 author of the most important advancements which the lunar theory 

 received in the period which intervened between the appearance of 

 the great M'orks of Laplace and Plana to which I have before re- 

 ferred. 



Jan. 28, 184.7 "On the Lunar Atmospheric Tide at St. He- 

 lena." By Lieut.-Colonel Edward Sabine, 11. A., For. Sec, R.S. 



The results of the observations made by Captain Lefroy, of the 

 Royal Artillery, Director of the Magnetical and Meteorological Ob- 

 servatory at St. Helena, are here given; from which it appears, on 

 the examination of thebarometricalchanges during seventeen months, 

 that a maximum of pressure corresponds to the moon's passage over 

 both the inferior and superior meridians, being slightly greater in 

 the latter case, and that a minimum corresponds nearly to the rising 

 and setting, or to six hours before and after the former periods. The 

 average atmospheric pressures are 28"2714 inches in the first cane, 

 and 28-267.5 in the last; the difference being 0-0039 inch. The 

 height ot the cistern of the barometer above the sea is 1764 feet; 

 and the latitude of the Observatory 15*^ 57' S. These results were 

 still further confirmed by tiiose of a series of observations during 



