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60 | ~ Remarks on the Tails of Comets. 
Productive as this subject has always been of the rudest spec- 
th absolute difficulty, and subjected as it 
rejudiees, I had little doubt that first im- © 
pressions at least, would’be geiferally unfavorable to the theory. 
In this I have been disappointed; for whatever may have been 
the misgivings of any one who has given ‘the subject deliber- 
ate thought, cursory peace, for the most part, have spared their 
criticisms. 
In a religious and literary Journal, published in Philadelphia, | 
under the title of “The Friend,” an anonymous article made its 
appearance, denouncing the theory as unphilosophical, and the 
train of objections which the writer presented, I hope to be for- 
tunate enough to examine with candor.* The first objection 
which he raises, and which he denominates the great one, is an 
nnqualified declaration, “ that there cannot be any substance per- 
vading space sufficiently dense to reflect the light thus cast upon 
it, so as to be perceptible,” adding that ‘‘no one can imagine that 
the exceedingly subtle vapor which may pervade the planetary 
space can possibly reflect the strongest light which can be cast 
upon it, for if such were the case, the light coming from the fixed 
stars would also be partly (if not entirely) reflected, and in con- 
sequence it would be barely possible for a sufficient quantit of 
light to escape reflection to render them visible, considering tl eir 
immense distance,” é¢c. Now if these views can be established, 
my theory is at once void. But I would ask, not for the sake of 
those who are familiar with the subject, but for the casual reader 
of these articles, to what point of the creation the whole light of 
the firmament would be reflected by a medium occupying all ‘ 
space! We will suppose, however, the author unhappy in the 
choice of the term, and that he would have had the light of the 
stars “partly, if not entirely” absorbed by the ethereal medium. 
To this I should say, that man having never witnessed any change 
of aspect under which he has contemplated the heavens, knows 
not, nor can he know, what degree of brightness the stars would 
have exhibited in the absence of an ethereal medium ; nor does 
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In a subsequent number of the paper, I invited the writer to a discussion n in 
this Journal, under his proper signature. In the hope that he would accept the in- : 
vitation, I have till now deferred any further notice of the article; and, although 
he has not appeared, his objections are made the basis of this additional essay, inas- i 
much as they afford an opportunity of further illustration of the theory. 
