230 Imperial Institute of France. 
IMPERIAL INSTITUTE OF FRANCE, 
FOR THE YEAR 1813. 
Mathematical and Physical Sciences. 
M. DEeLAMBRE, the secretary to this branch of the Institute, 
commences his report by lamenting the death of M. Lagrange, 
and the consequent suspension of the publication of the Me- 
chanique Analylique, the printing of the second yolume of which 
had just commenced when the author died. 
M. Laplace, the report proceeds, who last year favoured 
the scientific world with a complete Treatise on Probabilities, has. 
this year applied his theory to one of the most abstruse ques- 
tions in astronomy; viz . the origin of comets and the nature of 
their orbits. 
Dr. Herschel’s opinion on this subject is fresh in every one’s 
recollection. Perceiving almost every where in the celestial re- 
gions a faintly iene matter, interspersed with points, denser 
or more luminous, he conceived that in time the system of uni- 
versal attraction ‘might unite round these centres the nebulous 
matter with which they are surrounded; that in consequence of 
their mutual attraction two or more of these centres might ac- 
quire a movement, that this motion might carry them to the 
surface of the sphere over which the attractive energy of the sun 
exerts its influence; and that this motion, combined with the solar 
attraction, might convert these centres into as many new comets 
circulating around the sun, and obeying the same laws as the 
planets + that this may have been the origin of all the planets, 
and also of the sun ‘and stars ; for if we are constrained to admit 
the anterior existence of these immense bodies, we may with 
equal propriety assign the same date to the lesser bodies which 
circulate around them. 
These new orbits will of course be circular, elliptic, parabolic, 
or hyperbolic. 
In the ease of the orbits being circular, they will be always in- 
visible, unless, in defiance of probability, we suppose that their 
mass and inherent lights are sufficient to render them visible 
at so great a distance, for the nuclei or centres of Dr. Herschel 
are invisible by a common telescope. 
If the orbits are elliptical or parabolic, the comets may come 
so near the sun that they will become visible in a portion of their 
orbits comprehended between the perihelion and the parometer, 
and even somewhat beyond it. This supposition accounts with 
tolerable plausibility for the penn ena hitherto exhibited by 
comets Thei sir larger axis must go beyond the sphgte of the 
sun’s energy, which must extend ii eh further than the orbit of 
Uranus, ‘Such elongated ellipses will evidently be confounded 
with 
