PRECESSION OF THE EQUINOXES. 313 
From this solution we may date the important improve- 
ments of the lunar tables effected in the last century. 
The most beautiful astronomical discovery of anti- 
quity, is that of the precession of the equinoxes. Hip- 
parchus, to whom the honour of it is due, gave a com- 
plete and precise statement of all the consequences which 
flow from this movement. ‘Two of these have more 
especially attracted attention. 
By reason of the precession of the equinoxes, it is not 
always the same groups of stars, the same constellations, 
which are perceived in the heavens at the same season 
of the year. In the lapse of ages the constellations of 
winter will become those of summer and reciprocally. 
By reason of the precession of the equinoxes, the pole 
does not always occupy the same place in the starry 
vault. The moderately bright star which is very justly 
named in the present day, the pole star, was far removed 
from the pole in the time of Hipparchus; in the course 
of a few centuries it will again appear removed from it. 
The designation of pole star has been, and will be, ap- 
plied to stars very distant from each other. 
When the inquirer in attempting to explain natural 
phenomena has the misfortune to enter upon a wrong 
path, each precise observation throws him into new com- 
plications. Seven spheres of crystal did not suffice for 
representing the phenomena as soon as the illustrious 
_ astronomer of Rhodes discovered precession. An eighth 
same time by Euler, D’Alembert, and Clairaut. The two last-men- 
tioned geometers communicated their solutions to the Academy of 
Sciences on the same day, November 15, 1747. Euler had already in 
1746 published tables of the moon, founded on his solution of the same 
problem, the details of which he subsequently published in 1753.— 
Translator. 
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