304 M. Prevost on the Position of the Fossil Megalosaurus. 
same circumstances at the different epochs during which the 
two deposits were formed ; for, as he adds, the number and 
thickness of the oolitic strata interposed between the great oolite 
formation and that of the iron sand, prevent us from supposing, 
even for a moment, that the two deposits are identical. M. C. 
Prevost, who has visited Stonesfield, thinks, that the interposi- 
tion of numerous and thick beds of oolite, not being directly 
evident in any place between the strata which contain the same 
fossils, doubts may be raised regarding the relative position 
assigned to the limestone schists of Stonesfield, as well as regard- 
ing the place which should be occupied in the general series of 
the strata of the Earth, by those which, in the Forest of Tilgate, 
contain the same fossils. In both places, the strata, which con- 
tain the organic bodies, do not appear clearly covered by those 
of the formations which are said to be more recent ; and there 
are numerous considerations that might lead us to consider the 
two deposits as having been formed at a period which would be 
much newer than that of the oolitic formations ; in short, that 
they are tertiary and not secondary deposits. 
Art. XII. — Observations on the Comet of July 1825. By 
Professor Gautier*; 
The year 1825 will be memorable in the annals of astronomy 
for the number of Comets observed in it. During an interval 
of less than three months, it has presented to view four of these 
bodies, still so mysterious in their appearances and in their na- 
ture, but whose motions, as well as those of the other bodies of 
our system, appear entirely regulated by the great law of univer- 
sal gravitation. The most interesting of these appearances, in a 
theoretical point of view, was that of M. Encke’s small comet of 
short period, whose return was calculated and predicted by that 
able astronomer for the second time, and which was found again 
precisely in the place and with the motion which he had assigned 
to it. But the most remarkable of these comets with respect to 
the duration of its appearance and lustre, the only one which has 
been visible to the naked eye, and which has presented a percep- 
Bibliotheque Universelle, November 1825 ? 
