SEQUEL TO THE EPOCH OF NEWTON. 229 



Clairaut soon after. Lacaille, making use of these 

 results, and of his own numerous observations, 

 published Tables of the Sun. In 1786, Delambre 5 * 

 undertook to verify and improve these tables, by 

 comparing them with 314 observations made by 

 Maskelyne, at Greenwich, in 1775 and 1784, and in 

 some of the intermediate years. He corrected most 

 of the elements; but he could not remove the uncer- 

 tainty which occurred respecting the amount of the 

 inequality produced by the reaction of the moon. 

 He admitted also, in pursuance of Clairaut's theory, 

 a second term of this inequality depending on the 

 moon's latitude ; but irresolutely, and half-disposed 

 to reject it on the authority of the observations. 

 Succeeding researches of mathematicians have 

 shown, that this term is not admissible as a result 

 of mechanical principles. Delambre's Tables, thus 

 improved, were exact to seven or eight seconds 26 ; 

 which was thought, and truly, a very close coin- 

 cidence for the time. But astronomers were far 

 from resting content with this. In 1806, the French 

 Board of Longitude published Delambre's improved 

 Solar Tables; and in the Connaissance des Terns 

 for 1816, Burckhardt gave the results of a com- 

 parison of Delambre's Tables with a great number 

 of Maskelyne's observations ; far greater than the 

 number on which they were founded 27 . It appeared 

 that the epoch, the perigee, and the eccentricity, 



25 Voiron. Hist. p. 315. 26 Montucla, iv. 42. 



27 Airy. Report, p. 150. 



