102 BAILLY. 
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 observa- 
tories 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 be- 
ginning 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 de- 
termined 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 wit- 
ness in succession two of the most interesting astronomi- 
cal events: the first predicted and well established return 
of a comet; and one of those partial eclipses of the sun 
by Venus, that do not recur till after the lapse of a hun- 
dred and ten years, and from which science has deduced 
the indirect but exact method, without which we should 
still be ignorant of the fact that the sun’s mean distance 
from our earth is thirty-eight millions of leagues. 
I shall have completed the enumeration of Bailly’s 
astronomical labours performed before he became an 
academician, when I have added, from observations of 
the comet of 1762, the calculation of its parabolic orbit ; 
the discussion of forty-two observations of the moon by 
La Hire, a detailed labour destined to serve as a start- 
