1309 
Astronomy. — “The Motions of the Lunar Perigee and Node, 
and the Figure of the Moon.’ By Prof. W. pr Srrrer. 
1. The motions of the perigee and node of the moon have been 
derived from the observations by different investigators. 
For the perigee the resulting sideral motions are : 
E. W. Brown’) 146435".35 
P. H. CoweLr?®) ot 
E. J. pr Vos VAN STEENWIJK *) 29 
Newcoms *) ‚30 
All these values have been reduced to the value 50”.2500 of the 
constant of precession (see the preceding paper). The first three 
depend on meridian observations. The agreement between Cowerr. 
and Brown is excellent, but the result of pr Vos deviates rather 
more than can be explained by the mean errors (which are about 
+ 0".02 for each result). It is, however, in perfect agreement with 
the value derived by Nerwcoms from the discussion of occultations. 
The theoretical motion due to other causes than the figures of 
the earth and moon is by Brown’s theory: 
146428".77. 
There thus remains for these two causes 
I. Brown —COWELL dw = + 6".59 
I]. Newcomp—be Vos dw = + 6 .53. 
For the node the results derived by Newcoms*‘) and Brown’) are 
in perfect agreement. They both find 
— 69679" .44° 
The theoretical value, as above, is 
— 69673".22, 
The part due to the figures of the earth and moon is thus 
d), = — 6".22°. 
The mean errors of both values of do and of dS), so far as it 
is due to the observations, is + 0".02. The theoretical value, how- 
ever, in both cases is the sum of a large number of terms, each 
1) Monthly Notices, Vol. LXXIV, p. 419. 
2) Monthly Notices, Vol. LXV, p. 275. 
5) These Proceedings, Vol. XVI, p. 891. 
4) Researches on the motion of the Moon. (Second paper), p. 224. The cor- 
rections indicated by Brown, M.N. Vol. LXXIV, pp. 420 and 562 have been applied, 
5) Monthly Notices, Vol. LXXIV, p. 563, 
