of the Sun and Solar Syflem. 2^1 
go back in the order XVI, XV, XIV, &c. of the hour circle, 
fo as to decreafe in right afcenfion ; but according to M. de 
la land e^s table, excepting f3 Cyghi and y Arietis, all thefe 
motions really take place. With regard to the change of de- 
clination, we fee that every dar in the table fhould go towards 
the fouth ; and here we find but three exceptions in (3 and £ 
Cygni, and y Pifcium ; fo that upon the whole we have but five 
deviations out of 27 known motions which this hypothefis will 
not account for. And thefe exceptions mud be refolved into 
the real proper motion of the ftars. 
There are alfo fome very finking circumflances in the quan- 
tities of thefe motions that deferve oitr notice. Fird, Archu- 
rus and Sirius being the larged of the ftars, and therefore pro- 
bably the neared, ought to have the mod apparent motion, 
both in right afcenfion and declination, which is agreeable to 
obfervation, as we find by the table. Next, in regard to the 
right afcenfion only, Ardturus being better fituated to fhew 
its motion, by theorem II. p. ’261. ought to have it much larger, 
which we find it has. Aldebaran, both badlv fituated and con- 
fiderably fmaller than the two former, by the fame theorem 
ousdit to fhew but little motion. Procvon, better fituated than 
Sirius, though not quite fo large, fhould have aimed as much 
motion; for by the third theorem, on fuppefing it farther off 
becaufe it appears fmaller, the effect of the Tun’s motion will 
be leflened upon it; whereas, on the other hand, by the fecond 
theorem, its better fituation will partly compenfate for its 
greater diftance. This again is conformable to the table. 
e Cygni very favourably fituated, though but a fmall dar, 
fhould fhew it confiderably as well as a Aquilae ; whereas (3 
Cygni fhould have but little motion : and y Pifcium, bed 
Vol. lxxiii. o o fituated 
