372 COMET OF 1843. SECT. XXXV. 



would then be exposed to the temperature of the ethereal regions, 

 which is 239 below the zero point of Fahrenheit. A body of 

 such tenuity as the comet, moving with such velocity, must 

 have met with great resistance from the dense atmosphere of the 

 sun, while passing so near his surface at its perihelion. The 

 centrifugal force must consequently have been diminished, and 

 the sun's attraction proportionally augmented, so that it must 

 have come nearer to the sun in 1680 than in its preceding revo- 

 lution, and would subsequently describe a smaller orbit. As 

 this diminution of its orbit will be repeated at each revolution, 

 the comet will infallibly end by falling on the surface of the sun, 

 unless its course be changed by the disturbing influence of some 

 large body in the unknown expanse of creation. Our ignorance 

 of the actual density of the sun's atmosphere, of the density of 

 the comet, and of the period of its revolution, renders it impos- 

 sible to form any idea of the number of centuries which must 

 elapse before this event takes place. 



The same cause may affect the motions of the planets, and 

 ultimately be the means of destroying the solar system. But, as 

 Sir John Herschel observes, they could hardly all revolve in the 

 same direction round the sun for so many ages without impress- 

 ing a corresponding motion on the ethereal medium, which may 

 preserve them from the accumulated effects of its resistance. 

 Should this material medium revolve about the sun like a vortex, 

 it will accelerate the revolutions of such comets as have direct 

 motions, and retard those that have retrograde motions. 



The comet which appeared unexpectedly in the beginning of 

 the year 1843 was one of the most splendid that ever visited the 

 solar system. It was in the constellation of Antinous in the 

 end of January, at a distance of 115 millions of miles from the 

 earth, and it passed through its perihelion on the 27th of Feb- 

 ruary, when it was lost in the sun's rays ; but it began to be 

 visible about the 3rd of March, at which time it was near the 

 star Iota Cetse, and its tail extended towards the Hare. Before the 

 passage at the perihelion it had no tail ; but at that epoch the tail 

 suddenly darted out, and extended to a distance of 1826 millions of 

 miles in about an hour and a half a most inexplicable speed of 

 development, which indicates some powerful repulsive force at the 

 moment of the greatest proximity to the sun, at which time the 

 tails are formed. The brightness of the comet and the length 



