star itself,
whose rays reach the eye through atmospheric strata of various density,
temperature, and refrangibility, will appear to oscillate so much as to
render the true position of it almost unassignable; at the very moment
when extremely good definition of the object becomes indispensable to
insure correctness of measures, all becomes confused, either because the
eye-piece gets steamed with vapour, or that the vicinity of the very
cold metal occasions an abundant secretion of tears in the eye applied
to the telescope; the poor observer is then exposed to the alternative
of abandoning to some other more fortunate person than himself, the
ascertaining a phenomenon that will not recur during his lifetime, or
introducing into the science results of problematical correctness.
Finally, to complete the observation, he must read off the microscopical
divisions of the graduated circle, and for what opticians call _indolent
vision_ (the only sort that the ancients ever required) must substitute
_strained vision_, which in a few years brings on blindness.[6]

When he has scarcely escaped from this physical and moral torture, and
the astronomer wishes to know what degree of utility is deducible from
his labours, he is obliged to plunge into numerical calculations of
repelling length and intricacy. Some observations that have been made in
less than a minute, require a whole day's work in order to be compared
with the tables.

Such was the view that Lacaille, without any softening, exhibited to his
young friend; such was the profession into which the adolescent poet
plunged with great ardour, and without having been at all prepared for
the transition.

A useful calculation constituted the first claim of our tyro to the
attention of the learned world.

The year 1759 had been marked by one of those great events, the memory
of which is religiously preserved in scientific history. A comet, that
of 1682, had returned at the epoch foretold by Clairaut, and very nearly
in the region that mathematical analysis had indicated to him. This
reappearance raised comets out of the category of sublunary meteors; it
gave them definitely closed curves as orbits, instead of parabolas, or
even mere straight lines; attraction confined them within its immense
domain; in short, these bodies ceased for ever to be liable to
superstition regarding them as prognostics.

The stringency, the importance of these results, would naturally
increase in pro