e position
that it had in the year 1727, I found it necessary to continue my
observations through a whole period of the moon's nodes; at the end of
which I had the satisfaction to see, that the stars, returned into the
same position again; as if there had been no alteration at all in the
inclination of the earth's axis; which fully convinced me that I had
guessed rightly as to the cause of the phenomena. This circumstance
proves likewise, that if there be a gradual diminution of the obliquity
of the ecliptic, it does not arise only from an alteration in the
position of the earth's axis, but rather from some change in the plane
of the ecliptic itself; because the stars, at the end of the period
of the moon's nodes, appeared in the same places, with respect to the
equator, as they ought to have done, if the earth's axis had retained
the same inclination to an invariable plane."(2)

FRENCH ASTRONOMERS

Meanwhile, astronomers across the channel were by no means idle. In
France several successful observers were making many additions to the
already long list of observations of the first astronomer of the Royal
Observatory of Paris, Dominic Cassini (1625-1712), whose reputation
among his contemporaries was much greater than among succeeding
generations of astronomers. Perhaps the most deserving of these
successors was Nicolas Louis de Lacaille (1713-1762), a theologian who
had been educated at the expense of the Duke of Bourbon, and who, soon
after completing his clerical studies, came under the patronage of
Cassini, whose attention had been called to the young man's interest in
the sciences. One of Lacaille's first under-takings was the remeasuring
of the French are of the meridian, which had been incorrectly measured
by his patron in 1684. This was begun in 1739, and occupied him for
two years before successfully completed. As a reward, however, he was
admitted to the academy and appointed mathematical professor in Mazarin
College.

In 1751 he went to the Cape of Good Hope for the purpose of determining
the sun's parallax by observations of the parallaxes of Mars and Venus,
and incidentally to make observations on the other southern hemisphere
stars. The results of this undertaking were most successful, and were
given in his Coelum australe stelligerum, etc., published in 1763. In
this he shows that in the course of a single year he had observed some
ten thousand stars, and computed the places of one thousand nine hundr