SECTION IV. 



BIELA'S COMET. 



ON the 27th of February, 1826, M. Biela, an Austrian 

 officer, discovered a comet; and on computing its ele- 

 ments, it was found that the same body had been ob- 

 served in 1805 and in 1772. It was soon discovered 

 that the comet made its revolution round the sun in a 

 period of six years and two thirds. It was of course pre- 

 dicted that the comet would return in 1832. Computa- 

 tion also disclosed another fact, which excited no little 

 alarm. It was predicted that on the 29th of October, 

 1832, the comet would cross the plane of the ecliptic at 

 a distance of less than 20,000 miles from the earth's path. 

 Now the comet's radius, from observations in 1805, had 

 been determined to be greater than 20,000 miles ; from 

 which it followed, that a portion of the earth's orbit 

 would be included within the nebulosity of the comet. 

 It was found, however, that the earth would not arrive 

 at this point of its orbit until a full month afterward. 

 There was, therefore, no great danger of collision ; never- 

 theless, no little alarm was experienced by those not much 

 conversant with astronomy. The comet returned at the 

 time predicted, and was observed by Sir John Herschel ; 



