1 4 Remarks on the Lunar Theory, 



this point, relying, on the nine positions which he has been pleased 

 to denominate, p/00/5 of a recent Dehigc, although the whole of 

 them, so evidently point, either to the Gravel and other Deluges, 

 occurrinc before Man existed, or else to the period of the Exca- 

 vation of valleys, and denuding or carving out the Hills, which 

 still more evidently preceded, this grand Geological epoch, 



I am, yours, iicc. 

 July 6, 1820. ' A. B. C. 



III. Remarks on the Lunar Theonj. By JVfr. James Utting. 



To Mr. Tiiloch. 



Sir, — In the remarks on eclipses by Mr. Yeates, inserted in the 

 last volume of the Philosophical Magazine, this gentleman seems 

 desirous of proving, that the entire revolutions of the J) are li- 

 mited to a period of 912 solar years, in which time her relative 

 motions, with respect to the 0, and the whole pliaenomena of 

 eclipses are completed. On examining the solar and lunar mo- 

 tions during the above period, I find that 9 12 solar years* con- 

 tain 11279.8602955 lunations; consetjuentiy the ]) has not 

 completed her last revolution, wanting 50° 17' 37 ' of the line 

 of conjunction : the time in which the T) would pass through 

 this space would occupy about four days, two hours. The ]) 's 

 perigee also falls short of the same time by 28" 56' 46" ; from 

 which circumstance the 5 's anomaly would evidently be 79" 

 14' 23" short of the same line of conjunction. The longitude 

 of the J) 's node also falls short of conjunction 49' 7Y'- The 

 acceleration of the 5 's longitude during this period amounts to 

 only 14' 23"; consecjuently from the above statement it is not 

 possible to prove that 912 solar years constitute a complete lunar 

 period ; for either the solar year must be longer by C^' 30". 842, 

 or the synodic revolution of the }) must be 3l'.6 shorter, than 

 at the commencement of the present century, neitner of which 

 obtains, or is known to be the fact. In examining every con- 

 junction of the O and ]) that can tal^e place during a period of 

 upwards of ten thousand years, I find that the nearest coinci- 

 dence of the solar and lunar periods obtains at the completion 

 of 687 solar vearo, which are equal to 250921'' 9*^ 45' 36''.0. 

 This perjod contains 8497 lunations, or 250921'' 9=' 44' 3I".6: 

 the difference in time is 1'4''.4; the .1) having passed the line 

 of conjunction by 32".72. The acceleration of the j) in this 

 period amounts to 8' 7". 72. 



• The solar year is here taken as stated by Mr. De'ambre in his Theo- 

 retical and Practical Astronomy, 3 volumes quarto, 1S14; nnd the lunar 

 motions from the 4th edition of M. Laplace's Systera of thu World. 



In 



