(159 ) 
To the order zero 8 is constant and Æ is à quantity of 
the first order of small quanüties, and the same is true 
d\ d 
of cos 8 Æ. Therefore to the order zero _ = #, and to 
the same order 
Therefore to the first order of small quantities 
— À . in | C— A ] 
n sin & SIN | ? + nt }» 
d C 
— (8 + 90) — 
dt A 
sin (4+ d0 É à En 
— À . C — A 
LETTRE ci feu nt) 
These give the Eulerian diurnal nutations in obliquity 
and longitude, and as was foreseen they are excessively 
small. 
The third equation gives the correction to the sidereal 
time. If h denotes the true sidereal hour-angle deter- 
mined by the motion of the axes ABC, 
Thus À increases uniformly. 
If h + dh denotes the observed sidereal hour-angle 
C— À 
nl. 
n tan À sin & sin 
d C — 
Fri + dh) =n— 
