HALLEY'S COMET. 



187 



led him to correct the former result ; and he has since announced that the 

 time of its arrival at its nearest point to the sun will be on the morning of the 

 14th November. 



The comet appeared in the heavens in August, 1835, exactly in the position 

 it was predicted to have, and passed its perihelion, on the 16th November, 

 within 48 hours of the predicted epoch. 



The drawing of this comet usually given is here subjoined. 



One of the circumstances, not the least surprising, connected with this 

 comet, is the magnitude of its orbit. It is a very oblong oval, the total length 

 of which is about thirty-six times the earth's distance from the sun ; and the 

 greatest breadth about ten times that distance. The nearer extremity of the 

 oval is at a distance from the sun equal to about half the earth's distance ; and 

 the more remote extremity at a distance equal to thirty-five and a half times the 

 earth's distance from the sun. The earth's distance from the sun, is, in round 

 numbers, one hundred millions of miles ; the comet's least distance then will 

 be fifty millions of miles, and its greatest distance three thousand five hundred 

 and fifty millions of miles. Also, since the heat and light supplied by the sun 

 to bodies which surround it, diminish in the same proportion as the square of 

 the distance increases, it follows, that at the nearest distance of the comet, the 

 heat and light of the sun will be four times the heat and light at the earth, and 

 at the greatest distance they will be about twelve hundred times less. Also 

 the heat and light at the more remote extremity of the orbit, will be nearly live 

 thousand times less than at the nearer extremity ; so that while the sun 



