102. J. N. Stockwell—Researches on the Lunar Theory. 
since the calculated places were based on imperfect elements 
and an imperfect theory of the perturbations. 
No 
theory indicates a passage through just such conditions and 
changes. It is true, however, that it has never possessed the 
The labors of Newton and Halley reduced the errors of the 
theory to about the eighth part of a degree; while Mayer, by 
the aid of theory and more accurate observations, succeeded in 
reducing the errors to less.than the thirtieth part of a degree. 
Later still, the researches of Mason and Burg, according to the 
authority of LaPlace, reduced the errors of the theory to less 
than one-quarter of a minute of arc! Tf this last degree of pre- 
unmistakably indicated a growing discordance, which has con- 
tinued till the present time; and notwithstanding the labori- 
ous investigations which have been made in order to detect the 
laws and the cause, no satisfactory explanation has yet been 
attained. If we consider the nature and magnitude of the dis- 
cordances which now pertain to the best tables of the moon’s 
