35 



necessary part of the explanation. Of the residuals .1 on the other 

 hand there are. amongst the 10 quantities which were considered 



Mercury 



Venus 



Earth 



Mars 



de 



— Newcomb 



dt 



'Newcomb 

 d^^ ISeeliger 



dt 



sini 



/'Newcomb 

 c^I^iSeeliger 



dty 



C 



i Newcomb 

 Seeliger 

 A 

 C 



-0".88+0".50 



+8 .48 +0 .43 

 — .01 

 .00 

 — .02 



-f-0 .61 +0 .52 



— .04 



-f .55 



— .31 



+0".21 +0".31 



— .05 +0 .25 



— .10 



— .05 



— .12 



+0 .60+0 .17 



+0 .02 



-fO .01 



+0 .05 



+0 .38 +0 .80 ! -f .38 +0 33 



+0".02 +0".10 I +0".29 +0".27 



-fa .10+0 .13 



+0 .03 

 +0 .18 

 -0 .04 



— .14 

 — .12 

 -0 .15 



^-o .21 



+0 M 

 +0 .23 



-0 .22 +0 .27 

 (+0 .28) 

 -fl .18 

 -0 .17 



+0 .75 +0 .35 



+0 .16 



+0 .52 



.00 



+0 .03 +0 .22 



— .20 



— .11 



-0 .24 



-0 .01 ±0 .20 



+0 .01 



+0 .05 



— .01 



by Seeliger, 3 residuals exceeding their mean eri'or. This in itself 

 would not be sufticient to condemn the hypothesis, but the residual 

 for the secular variation of the inclination of the ecliptic (-[- l".18) 

 is entirely inadmissible. We conclude therefore that the rotation ]\ 

 is a vital part of the explanation. 



The great intluence of the ellipsoid h on the ecliptic is, of course, 

 due to the large inclination of its equator. If this equator was e.g. 

 supposed to coincide with the invariable plane of the solar system, 

 instead of with the sun's ecpiator, this intluence would be much 

 smaller. It is impossible to decide a priori whether it will be found 

 possible so to adjust the position of the equator and the density of 

 this ellipsoid that it has the desired effect on the node of Venus 

 without appreciably affecting the earth's orbit. 



The motion of the node of the earth's orbit is the planetary pre- 

 cession. Calling this A, we have, for t ^ t„ 



3* 



