to the "Inertialsystem". This rotation is equivalent with a correction 

 to tlie coiislant of precession. The value of this constant which is 

 implied in Nevvcomb's anomalies is that used in his first fundamental 

 catalogue (Astr. Papers Vol 1). In "The Observatory" for July 1913 

 I have shown that this constant requires a correction of -j- 1".24 

 (per century). Consequently, of Skeliger's rotation r onlj' the part 

 i\ = r — 1".24 can be considered as a real rotation. 



The position of the equatorial plane of the ellipsoid a was deter- 

 mined by Seeliger from the equations of condition: he found it not 

 much different from the sun's equator. For the ellipsoid h the sun's 

 equator was adopted as the equatorial plane. 



It is important to consider the part which is contributed by each 

 of the three hypotheses towards the explanation of the anomalies. 

 B}^ the way in which Seeliger has published his results this is very 

 easy. It then appears that the ellipsoid n is practically only necessary 

 for the explanation of the anomaly in the motion of the perihelion 

 of Mercury, and has very little influence on the other elements. 

 Similarly the ellipsoid b affects almost exclusively the node of Venus. 

 The rotation /■ of course has the same effect on all perihelia and 

 nodes. In the following Table are given Newcomb's anomalies together 

 with the residuals which are left unexplained by Seeliger's hypothesis. 

 In addition to Seeliger's residuals I also give residuals which are 

 derived : A. by rejecting the rotation ?■/), and C. by omitting the 

 second ellipsoid. The constants implied in the three sets of residuals 

 are thus 

 Seeliger q, = 2.18 X lO-i^ q, = 0.31 X iO-^^ r, = + 4".61 

 A 2.42 0.93 



C 2.03 +6.85, 



where q^ and q., are the densities of the two ellipsoids expressed 

 in the sun's density as unit. 



di 

 Seeliger did not compute the value of for the earth. The resi- 



'■ dt 



dual given in the table is derived from the preceding paper by 

 Mr. WoLTJEii. 



From the fable it appears that the residuals C are quite as satis- 

 factory as those of Seeliger. Consequently the ellipsoid h is not a 



1 ) The residuals A have already been given in the above quoted paper in "Tlie 

 Observalory". The density q. is there erroneously given as 0.37 instead of 0.93 

 (the correction to Seeliger's value having been taken as 0.2 times this value, 

 instead of 2.0). I have used the figures as published by Seeliger. The small 

 deviations found by Mr. Woltjer are of no importance. 



