434 



PHILOSOPHICAL TRANSACTIONS, 



[anno 1747-8. 



defect in an hypothesis that pays no regard at all to it. But whether these dif- 

 ferences do arise from the cause already hinted at ; or whether they proceed from 

 any defect of the hypothesis itself in any other respect ; it will not be very mate- 

 rial in point of practice ; since that hypothesis, as it was before laid down, ap- 

 pears to be sufficient to solve all the phenomena, to as great a degree of exactness 

 as we can in general hope or expect to make observations. For if I take the 

 mean of all the numbers in the last column of the following table for n Ursae 

 Majoris, and compare it with any one of 164 observations that were taken of it, 

 the difference will not exceed 3 seconds. 



II Ursae Majoris. 



1727 October 17 



1728 January 24 



July 17 



October 11 



1729 January l6 



July 21 



1730 July 19 



December .... 28 



1731 September 18 



1732 January 10 



April 13 



1734 July 11 



1735 September 10 



1736 8 



1737 July 3 



1738 June 29 



1739 April 25 



1740 June 3 



1741 September .... 23 



1745 5 



1746 . 20 



1747 2 



It may be perceived, by inspecting the tables which contain the observations 

 of « Cassiopeae and -/i Ursae Majoris, that the greatest differences that occur in 

 them may be diminished, by supposing the true pole of the equator to move 

 round the point ?, in an ellipsis, instead of a circle. For if the transverse axis, 

 lying in the direction AC, be IS', and the conjugate, as db, be about 16*; the 

 equations, resulting from such an hypothesis, will make the numbers in the last 

 columns agree with each other, nearer than as they now stand. But since this 

 would not entirely remove the inequalities in all the positions of the moon's nodes, 

 I shall refer the more accurate determination of the locus of the true pole to 

 theory ; and at present only give the equations for the precession of the equinoc- 

 tial points, and the obliquity of the ecliptic, as also the real quantity of the au- 



. : .4V>/ 



