41. 



ON THE GENERAL VALUES OF THE OBLIQUITY OF THE ECLIPTIC, AND 

 OF THE PRECESSION AND INCLINATION OF THE EQUATOR TO THE 

 INVARIABLE PLANE, TAKING INTO ACCOUNT TERMS OF THE SECOND 

 ORDER*. 



[From The Observatory, No. 109 (1886).] 



IF we adopt the values of the precession and nutation employed by 

 Peters in his classical work Numerus Constants Nutationis, I find that 

 the ratio of the sum of the masses of the Earth and Moon to the 

 mass of the Moon is that of 82' 834 to 1, a result which differs slightly 

 from that found by Peters from the same data. 



The amount of precession caused by the Sun's action depends in a 

 slight degree on the eccentricity of the Earth's orbit. In order to find 

 the precession for an indefinite period, it will be proper to employ the 

 mean value of the square of this eccentricity instead of the value of this 

 quantity at the present time. 



Taking this circumstance into account, and also introducing the small 

 correction of the coefficient of precession which depends on the square of 

 the coefficient of nutation, I find that if ca be the obliquity of the 



* Abstract of a paper read Sept. 11, 1884, at the Philadelphia meeting of the American 

 Association for the Advancement of Science. 



