Miscellaneous Notices Respecting Cholera. 183 
the old atmosphere and divided it amongst them, poor Vesta is left 
without any visible envelope, purely naked. ‘This puzzles Mr. Ara- 
go very much. Mr. Herapath, an English first rate mathematician, 
who for some cause or other isnot in good odor with the Royal So- 
ciety, has published in the Times Newspaper of last month, (October) 
a letter in which he most ingeniously proposes an hypothesis in itself 
extremely rational, which is that Vesta was the satellite of the old 
planet, an hypothesis which the different period of its revolution and 
the difference in the elements of its orbit tend strongly to confirm. 
Atmospheres of Planets.—The atmosphere of our own moon is so 
extremely rare, low, and transparent, that its existence was long 
doubted or denied. I have, this year, had the good fortune in our 
murky atmosphere to catch two glimpses of Mercury on the sun’s disk, 
which very few persons in England saw. One occultation of Saturn 
by the moon, very perfect, one of Aldebaran during broad sunshine ; 
and the planet Saturn without any vestige of its ring, looking as much 
shorn of its glory, as an English judge would be when deprived of his 
robes and wig. 1 think Mr. Herapath’s hypothesis respecting Vesta 
well deserves a place in your Journal, with the brief section on the 
new planets by Arago, ‘in the essen du Roi. To descend from 
the Heavens to the earth. 
. Tertiary Formations.—The greatest advance recently aie in 
Geology, that 1 am acquainted with, is the discovery of the wide 
spread avai of tertiary formations, analogous, though perhaps not 
identical with the tertiary beds of France and England. In this dis- 
covery your country bears a full share; there can be little doubt that 
the organic remains sent from the United States, are analogous to 
those in the European beds, and also to those in part of the chalk 
formation. 
Supposed Jmmutability of Species. —With respect to the immuta- 
bility of species it may be true in the higher orders of animals, but 
in Mollusca having no internal skeleton, I am fully persuaded that 
change of circumstances may produce important changes of form, 
changes quite sufficient to make our Cabinet Philosophers regard 
them as distinct species ; but nature is not restricted by these artificial 
arrangements. 
