84- Things not generally Known. 



to the discovery of the asteroids, it seemed almost contrary to 

 the laws of probability that the discovery of another member 

 of the planetary system should prove its failure as an univer- 

 sal rule. 



MAGNITUDE OF COMETS. 



Although Comets have a smaller mass than any other cos- 

 mical bodies being, according to our present knowledge, pro- 

 bably not equal to 3o ' 00 th part of the earth's mass yet they 

 occupy the largest space, as their tails in several instances ex- 

 tend over many millions of miles. The cone of luminous va- 

 pour which radiates from them has been found in some cases 

 (as in 1680 and 1811) equal to the length of the earth's distance 

 from the sun, forming a line that intersects both the orbits of 

 Venus and Mercury. It is even probable that the vapour of 

 the tails of comets mingled with our atmosphere in the years 

 1819 and 1823. Humboldt's Cosmos, vol. i. 



COMETS VISIBLE IN SUNSHINE THE GREAT COMET OF 1843. 



The phenomenon of the tail of a Comet being visible in 

 bright Sunshine, which is recorded of the comet of 1402, oc- 

 curred again in the case of the large comet of 1843, whose 

 nucleus and tail were seen in North America on February 28th 

 (according to the testimony of J. G. Clarke, of Portland, State 

 of Maine), between one and three o'clock in the afternoon. 

 The distance of the very dense nucleus from the sun's light 

 admitted of being measured with much exactness. The nu- 

 cleus and tail (a darker space intervening) appeared like a very 

 pure white cloud. American Journal of Science, vol. xiv. 



E. C. Otte, the translator of Bonn's edition of Humboldt's 

 Cosmos, at New Bedford, Massachusetts, U.S., Feb. 28th, 1843, 

 distinctly saw the above comet between one and two in the 

 afternoon. The sky at the time was intensely blue, and the 

 sun shining with a dazzling brightness unknown in European 

 climates. 



This very remarkable Comet, seen in England on the 17th 

 of March 1843, had a nucleus with the appearance of a planetary 

 disc, and the brightness of a star of the first or second magni- 

 tude. It had a double tail divided by a dark line. At the 

 Cape of Good Hope it was seen in full daylight, and in the im- 

 mediate vicinity of the sea ; but the most remarkable fact in 

 its history was its near approach to the sun, its distance from 

 his surface being only one- fourteenth of his diameter. The heat 

 to which it was exposed, therefore, was much greater than that 

 which Sir Isaac Newton ascribed to the comet of 1680, namely 

 200 times that of red-hot iron. Sir John Herschel has com- 

 puted that it must have been 24 times greater than that which 



