145 



Thus it appears that during the entire period of the ob- 

 servations in 1852, the distance of the two bodies from 

 each other remained nearly constant, and this distance 

 was nearly seven times as great as the greatest distance in 

 1846. A comparison of the observations made in 1852 

 with those made in 1846, might be expected to determine 

 the orbit of each comet with great precision. But here 

 an unexpected difficulty presented itself. It seems im- 

 possible to decide whether what was known as the pri- 

 mary nucleus in 1846, is the same with the comet A or B 

 in 1852 ; for all the observations are about equally well 

 represented by either hypothesis, but there is a slight dif- 

 ference in favor of the hypothesis that the comet B in 

 1852 was the same as what we have called the primary 

 nucleus in 1846. 



What then is the history of these two bodies ? Are 

 they both new comets is one a new comet and the other 

 Biela or are both of them parts of Biela ? 



"We have seen that the distance of the two comets from 

 each other in 1852 was more than one and a half millions 

 of miles, while in 1846 it was only about 200,000 miles. 

 On the 1st of December, 1845, the distance was only 

 117,000 miles, and by following both bodies backward we 

 find that about the last of September, 1844, their distance 

 from each other was only 15,000 miles. Now the radius 

 of the primary nucleus has been computed to be 20,000 

 miles ; from which we must conclude that the two bodies 

 were in contact in September, 1844, and each body was 

 within a few hours' motion, of the place where Biela's 



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