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Remarks on the Tails of Comets. _ 59 
en of eighteen inches; they are only half an inch apart at 
e socket, and project right and left, with the concavity forward. The 
» teeth have the mammillose or mastodon shape and conformation, and are 
three and a half inches in length by two and a half in breadth. Thelower 
jaw is wanting. 
There is an os humeri, probably of a megalonyx, which measures in 
length one foot eight inches, the ulna of the same animal, and also other 
bones, probably the radii, with some of the last phalanges. 
Dr. Horner stated, that his sketch of this rich accumulation of fossil 
remains and their examination were very imperfect, and the less instruc- 
tive to him, for the want of standards of comparison in perfect skeletons, 
_ and in plates, neither of which means of elucidation exist in St. Louis, 
and he expressed a hope, that “their diligent and deserving collector 
would furnish the scientific world with exact plates of such as are rare or 
unknown.” 
Arr. V.— Additional Remarks on the Tails of Comets ; by Wm. 
: Mircuett, of Nantucket, Mass. 
Ir is a weakness common, I believe, to most men, to adhere 
with more or less pertinacity to first impressions ; it is manifested 
in childhood, and is often strengthened by age. From this delu- 
sive error, in the discussion in which I now engage, I can scarce- 
ly hope, though I strongly desire to be entirely free. The end 
of all inquiry should be truth, which is the only legitimate object. 
n Vol. xxxvi, No. 1, I was indulged with the occupancy of 
a few pages for the publication of an essay on the tails of comets. 
The object of the article and its only hope, was to invite the at- 
tention of those familiar with this and kindred subjects, to a very 
simple, and to myself, satifactory explanation of the phenome- 
non; being principally the result of my own observations on the 
Comets visible in this part of the world during the last thirty 
years; viz. that their tails are formed by the sun’s rays, slightly 
refracted by the nucleus in traversing the envelope of the comet, 
and uniting in an infinite number of points beyond it, throwing 
® stronger than ordinary light on the ethereal medium, near to, 
°r more remote from the comet, as the ray from tts relative position 
and direction is more or less refracted. In support of this theory, 
T adduced very briefly the facts and the reasoning which had es- 
tablished it in my own mind. : 
