456 Opposition of Geres. 



nified, to makeup a visible quantity." May 1, " The diameter 

 of the coma of Ceres is about five times as large as the 

 disc." 20-ft. reflector, power 477, the coma considerable. 

 May 2, " Ceres is better defined than I have generally seen it. 

 Its disc is strongly marked, and when I see it best, the hazi- 

 ness about it hardly exceeds that of the stars of an equal size." 

 May 4, 10-ffc. reflector, " I compared Ceres with two fixed 

 stars, which in the finder appeared to be of very nearly the 

 same magnitude with the asteroid, and found that its coma 

 exceeds their aberration but in a very small degree. 

 20-ffc. reflector, found that the coma . . did not much 

 exceed that of the stars. I also found that even the fixed stars 

 differ considerably in this respect among themselves. The 

 smaller they are, the larger in proportion will the attendant 

 haziness show itself. A star that is scarcely perceptible becomes 

 a small nebulosity." In drawing, however, his final result, 1$. 

 admits the existence of a visible nebulous atmosphere. 



Schroter is more positive upon the subject, and his little 

 book, published in 1 805, and entitled Lilienthcdische Beobach- 

 tungen, contains a good deal of curious information with respect 

 to the three minor planets known up to that date, Ceres, Pallas, 

 and Juno. The former, having been discovered by Piazzi at 

 Palermo on the first night of the present century (a memorable 

 epoch in our knowledge of the solar system), and subsequently 

 of course lost sight of in its approach to the sun, was once 

 more detected, in consequence of Gauss's calculations, by 

 Olbers at Bremen, exactly twelve months after the date of its 

 discovery, and on January 6, 1802, it was seen at Schroter' s 

 observatory, at Lilienthal, near Hamburg, by his assistant 

 Harding, with an excellent 13-ft. Newtonian reflector of 9*5 

 inches aperture, powers 136 and 288,* as a faint nebulous 

 object, about 2 //- 5 in diameter. January 25, Schroter saw the 

 disc as sharply defined as that of Uranus, encompassed by a 

 very narrow mist, and measuring, with the latter, 2"*514. 

 January 26, it had a more nebulous outline, though in a clearer 

 air, measuring 2 //- 687. January 28, much the same, well but 

 not sharply defined, 2 //, 795. January 31, very ill defined, no 

 distinct disc, though in a very clear sky, 2 //# 930. He now 

 began to be struck with the regular increase in the measures. 

 February 5, better defined than usual, and planetary-looking, 

 though not as distinct as on January 25 ; measuring very 

 satisfactorily 3"'46o. February 10, tho air was fine, but its 



* This instrument, made by Schrader, of Kiel, in 1792, appears to have been 

 of very superior quality ; at the distance of 1 10 paces, the smallest print could be 

 read with a power of 1500. Schroter employed it extensively in his lunar re- 

 searches. It has been carefully preserved, and was advertised for sale two or 

 three years ago. 



