305 
Professor Gautier on the Cornet of July 1825. 
tible tail, is that which wns discovered toward the middle of 
July in the constellation of Taurus. It appeared without being 
expected, as a mere nebulosity, and had at first a motion ex- 
tremely slow. Its motion was afterwards gradually accelerated ; 
it became visible to the naked eye ; became invested with a tail, 
which gradually enlarged ; and, after having shone for some 
time in our horizon in the constellation of the Whale, disappear- 
ed from our view about the middle of October towards the south, 
in the constellation of the Apparatus Sculptoris. The first ele- 
ments of this comet with which I was acquainted, indicating that 
it would only pass to its perihelion in the month of December next, 
and thus leaving the hope of still seeing it again, I was curious 
to assure myself of these circumstances, by calculating myself 
the elements of its orbit, and deducing from them the different 
positions in which it ought to be found, with relation to the sun 
and the earth. It is the results of this calculation that I present 
here for the use of those who may be interested in the subject. 
As I did not possess the means of making sufficiently regular 
and precise observations of this comet myself, I have taken for 
the basis of my calculation three observations made by M. Plana, 
at the Royal Observatory of Turin, and inserted in the third 
number of the thirteenth volume of the Correspondance Astro - 
nomique of Baron Zach, namely, those of the 25th August, of 
the 5th, and of the 25th September. For the determination of 
the elements of the parabolic orbit of the comet according to 
these observations, I have made use of the method of M. de 
Laplace, in the application of which I have profited by the ex- 
cellent. instructions which I have previously had the advantage 
of receiving from MM. Biot and Bouvard. The elements which 
I have obtained are intermediate between those of MM. Ca- 
pocci and Hansen, the only ones with which I was acquainted, 
and approach nearest the latter. 
For the purpose of presenting the subject in a clearer manner, 
I have traced, on a small scale, in Plate IX. Fig. 5. the orbit 
of the earth, and the portion of the parabolic orbit of the comet 
near its passage to the perihelion, 'designating by the same letters 
in both the positions of these two stars corresponding to the same 
instants, those of the comet being indicated in large, and those of 
the earth in small letters. The plane of the figure is that of the 
