Miscellaneous Notices Respecting Cholera. 183 



the old atmosphere and divided \i 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 is not in good odor with the Royal So- 

 ciety, has pubhshed 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. I 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 Annuajre du Roi. To descend from 

 the Heavens to the earth. 



Tertiary Formntions. — The greatest advance recently made in 

 Geology, that 1 am acquainted with, is the discovery of the wide 

 spread extent 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 Immutability 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. 



