68 Remarks on the Tails of Comets. 



limited to the planetary system, but manifest also in the sidereal 

 regions, affecting every particle of matter in the whole amplitude 

 of nature. What, then, exempts the tail of a comet from its in- 

 fluence ? Where, in these immensely extended trains of attenu- 

 ated matter, if they are such, is the effect of Saturn's or of Jupi- 

 ter's attraction, to say nothing of the smaller bodies of the sys- 

 tem among which they are so majestically sweeping? Where is 

 that sinuous form which would necessarily result from this une- 

 qual and inevitable action ? If any where, it has escaped my re- 

 search as well as observation ; the solitary and trifling peculiarity 

 noticed at one period in the extremity of the tail of the comet of 

 1769, cannot be deemed an exception ; and all reasonings on this 

 subject, having matter for their basis, are alike futile. Thus, the 

 theory of Sir Wm. Herschel, which supposed that the solar heat 

 consolidated the tail and envelope on the surface of the nucleus — a 

 theory supposed by Milne to be completely established by the rela- 

 tive appearance and magnitude of the comet of 18 11, was as com- 

 pletely overthrown by the appearance and magnitude of Halley's 

 comet in 1835. Indeed, to suppose for a moment that these im- 

 mense images, so to speak, consist of matter, requires a credulity 

 equal to that which gave credence to the primum mobile and 

 coelum empyrium of Ptolemy. And if they are not matter, the 

 conclusion is irresistible that they can be no other than the solar 

 beams augmented by the refractive power of the envelope, and 

 manifested to our vision by the medium on which they fall ; a 

 theory not less plausible for the explanation which it affords to 

 the general phenomena of these cometary appendages, than for 

 the great simplicity which distinguishes it. This, then, is the 

 ignis fatuus^ which, in the imagination of men, has given to the 

 sun a blow so formidable as to detach from its surface the world 

 we inhabit, and to that world in its turn, a shock so terrible, that 

 mountains and rocks have been rent asunder, burying indiscrimi- 

 nately in the ruins, animals originally the most remote from each 

 other, — and no marvel so long as a wand of such enormous mag- 

 nitude was admitted to be material. I trust, however, that a care- 

 ful and a candid consideration of this interesting subject, will re- 

 sult in the conviction that the tail of a comet is a mere sunbeam, 

 as harmless as that which, by suspended dust, becomes visible from 

 the puncture in the ceiling. 



Nantucket, 11th mo. 4th, 1840. 



