zure sky, followed with
their eyes the general and majestic movements of the starry sphere; they
ascertained the respective displacements of the planets, the moon, the
sun; they noted the date and hour of eclipses; they sought out whether
simple periods would not enable them to foretell these magnificent
phenomena a long time beforehand. Thus the Chaldaeans created, if I may
be allowed the expression, _Contemplative Astronomy_. Their observations
were neither numerous nor exact; they both made and discussed them
without labour and without trouble.

Such is not, by a great deal, the position of modern astronomers.
Science has felt the necessity of the celestial motions being studied in
their minutest details. Theories must explain these details; it is their
touchstone; it is by details that theories become confirmed or fall to
the ground. Besides, in Astronomy, the most important truths, the most
astonishing results, are based on the measurement of quantities of
extreme minuteness. Such measures, the present bases of the science,
require very fatiguing attention, infinite care, to which no learned man
would bind himself, were he not sustained, and encouraged by the hope of
attaining some capital determination, through an ardent and decided
devotion to the subject.

The modern astronomer, really worthy of the name, must renounce the
distractions of society, and even the refreshment of uninterrupted
sleep. In our climates during the inclement season, the sky is almost
constantly overspread by a thick curtain of clouds. Under pain of
postponing by some centuries the verification of this or that theoretic
point, we must watch the least clearing off, and avail ourselves of it
without delay.

A favourable wind arises and dissipates the vapours in the very
direction where some important phenomenon will manifest itself, and is
to last only a few seconds. The astronomer, exposed to all the
transitions of weather, (it is one of the conditions of accuracy,) the
body painfully bent, directs the telescope of a great graduated circle
in haste upon the star that he impatiently awaits. His lines for
measuring are a spider's threads. If in looking he makes a mistake of
half the thickness of one of these threads, the observation is good for
nothing; judge what his uneasiness must be; at the critical moment, a
puff of wind occasioning a vibration in the artificial light adapted to
his telescope, the threads become almost invisible; the