64 Reraarks on the Tails of Comets. 



ed so near the sun that it became very brilliant, and was more- 

 over accompanied by three distinct envelopes, a condition favora- 

 ble, it must be acknowledged, to the multiplication of tails, es- 

 pecially when we notice that the ratio is such as to produce the 

 number usually assigned, each beam of light being numbered as 

 a tail. The diversity of circumstances exhibited in the heads of 

 different comets, renders it rather a matter of surprise that so great 

 a uniformity should prevail in the general circumstances of the 

 tails. 



We come next to the consideration of another and a distinct 

 class of phenomena, that of the secondary tail, or what Prof Jos- 

 lin denominates the "supernumerary tail," distinguishable in the 

 comets of 1 823 and 1835. The former was noticed by Prof Biela, 

 at Prague, and President Day, of Yale College, and by them rep- 

 resented as forming an angle of 178^ with the primary tail. The 

 latter was noticed by many observers in this country at various 

 angles with the primary tail, a singular discrepancy prevailing in 

 the various published accounts. Of this extraordinary appear- 

 ance in the comet of 1823, I have only to express my conviction, 

 not having myself seen it, that it proceeded from the same cause 

 that produced the same phenomenon in the comet of 1835. which 

 was most manifestly the image of the true tail of the comet, pro- 

 jected on the spherical surface of the envelope, visible only under 

 fixed angles, and changing its aspect and position with the rela- 

 tive change in the position of the three bodies, affected also by 

 fluctuations in the comet's envelope. So faithful was the delin- 

 eation, that the brighter borders of the tail gave to the reflected 

 image the form of a sector. 



Our writer having denounced all theories as equally unsatisfac- 

 tory, recalls the expression, and acknowledges the theory of Dr. 

 Hamilton, of Dublin, to " approach nearer the truth than any with 

 which he is acquainted." 



The theory of Hamilton supposed the tails of comets and the 

 Aurora Borealis to be kindred effects of electricity. In support 

 of this theory, the writer adduced a remark of Halley, "that the 

 streams of light so much resemble the long tails of comets, that 

 at first sight they might well be taken for such ;" and as a fur- 

 ther confirmation of this theory, introduces the following quota- 

 tion from Prof. Vince's System of Astronomy, viz. "The comet 

 of 1607 appeared to shoot out at the end of its tail. Le P. Cy- 



