portion as the resemblance between the announced orbit
and the real orbit became more evident.

This was the motive that determined so many astronomers to calculate the
orbit of the comet minutely, from the observations made in 1759,
throughout Europe. Bailly was one of those zealous calculators. In the
present day, such a labour would scarcely deserve special mention; but
we must remark that the methods at the close of the eighteenth century
were far from being so perfect as those that are now in use, and that
they greatly depended on the personal ability of the individual who
undertook them.

Bailly resided in the Louvre. Being determined to make the theory and
practice of astronomy advance together, he had an observatory
established from the year 1760, at one of the windows in the upper story
of the south gallery. Perhaps I may occasion surprise by giving the
pompous name of _Observatory_ to the space occupied by a window, and the
small number of instruments that it could contain. I admit this feeling,
provided it be extended to the Royal Observatory of the epoch, to the
old imposing and severe mass of stone that attracts the attention of the
promenaders in the great walk of the Luxembourg. There also, the
astronomers were obliged to stand in the hollow of the windows; there
also they said, like Bailly: I cannot verify my quadrants either by the
horizon or by the zenith, for I can neither see the horizon nor the
zenith. This ought to be known, even if it should disturb the wild
reveries of two or three writers, who have no scientific authority:
France did not possess an observatory worthy of her, nor worthy of the
science, and capable of rivalling the other observatories of Europe,
until within these ten or twelve years.

The earliest observations made by Bailly, from one of the windows in the
upper story of the Louvre gallery that looks out on the Pont des Arts,
are dated in the beginning of 1760. The pupil of Lacaille was not yet
twenty-four years old. Those observations relate to an opposition of the
planet Mars. In the same year he determined the oppositions of Jupiter
and of Saturn, and compared the results of his own determinations with
the tables.

The subsequent year I see him associated with Lacaille in observing the
transit of Venus over the sun's disk. It was an extraordinary piece of
good fortune, Gentlemen, at the very commencement of his scientific
life, to witness in succession two of the most inte