23. 



REPLY TO VARIOUS OBJECTIONS AGAINST THE THEORY OF THE 

 SECULAR ACCELERATION OF THE MOON'S MEAN MOTION (WITH 

 POSTSCRIPT.) 



[From the Monthly Notices of the Royal Astronomical Society (1860). Vol. XX.] 



IF I have hitherto published no reply to the " Observations " of M. de 

 Pontecoulant, contained in the Monthly Notices of July last, it is not be- 

 cause the task presented any difficulty, for the fallacies which pervade M. 

 de Pontecoulant' s communication were perfectly evident to me from the very 

 first. I thought that any competent person who chose to look into my 

 Memoir " On the Secular Acceleration," and into these observations upon it, 

 might be safely left to form his own judgment on the matter. Again, I 

 had some hopes that M. de Pontecoulant might be led to see and ac- 

 knowledge the errors into which he had fallen, and with that object in 

 view I sent to him, on more than one occasion, through a friend, com- 

 munications which appeared to me amply sufficient to expose the fallacies 

 contained not only in his printed " Observations," but also in several private 

 letters which he subsequently wrote upon the subject. I find, however, 

 that M. de Pontecoulant, in a letter which he has lately caused to be 

 circulated among the members of the French Institute, has ventured to 

 ignore these communications of mine altogether, and to speak as if his 

 observations had been admitted without dispute. Under these circumstances, 

 as my further silence might be misconstrued, I beg leave to offer to the 

 Society the following remarks. 



