C 424 ] 
as they ought to do. This may feem the more 
ftrange, if regard be had to the conclufions, relating 
to the nodes of a fatellite, derived from this very 
affumption. But, that thefe conclufions are true, is 
owing to a fecond, or fubfequent miflake, at Art. 
2/j where the meafure of the lull’s force is taken 
the half, only, of the true value ; by means whereof 
the motion of the equinoctial points of the ring is 
reduced to its proper quantity, and the motion of 
the equinoctial points of the terreftrial fpheroid, to 
the half of what it ought to be. 
That expert geometrician M. Cha. Walmfley, in 
his EfTay on the Preceffion of the Equinox, printed 
in the lad: volume of the Philofophical TranfaCtions, 
has judicioufly avoided all miftakes of this laft kind, 
refpeCting the fun’s force, by purfuing the method, 
pointed out by Sir Ifaac Newton ; but, in deter- 
mining the effeCt of that force, has fallen into others, 
not lefs confiderable than thofe above adverted to. 
In his third Lemma, the momentum of the whole 
Earth, about its diameter, is computed on a fuppo- 
lition, that the momentum or force of each particle is 
proportional to its distance from the axis of motion, 
or barely as the quantity of motion in fuch particle, 
confidered abflraCtedly. No regard is, therefore, had 
to the lengths of the unequal levers, whereby the par- 
ticles are fuppofed to receive and communicate their 
motion : which, without doubt, ought to have been 
included in the confideration. 
In his firft propofition, he determines, in a very 
ingenious and concife manner, the true annual motion 
of the nodes of a ring (or of a fingle fatellite) at the 
earth’s equator, revolving with the earth itfelf, about 
its 
