60 Remarks on the Tails of Comets. 



Productive as this subject has always been of the rudest spec- 

 ulation, surrounded with absolute difficulty, and subjected as it 

 still is to formidable prejudices, I had little doubt that first im- 

 pressions at least, would be generally 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 readers, for the most part, have spared their 

 criticisms. 



In a rehgious 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 

 unqualified 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 quantity of 

 light to escape reflection to render them visible, considering their 

 immense distance," &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 



* In a subsequent number of the paper, I invited the writer to a discussion 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- 

 much as they afford an opportunity of further illustration of the theory. 



