380 



COSMOS. 



feet reflector, by which means he was enabled to render 

 his earlier delineations of 1824-1826 more perfect." The 

 positions of 150 stars, mostly of from the fifteenth to the 

 eighteenth magnitudes, in the vicinity of Orionis were 

 determined. The celebrated trapezium, which is not sur- 

 rounded by a nebula, is formed of four stars of the fourth, 

 sixth, seventh, and eighth magnitudes. The fourth star was 

 discovered (in 1666?) by Dominique Cassini, at Bologna f 

 the 5th (7') in 1826, by Struve ; and the sixth (a'), which is 

 of the thirteenth magnitude, in the year 1832, by Sir John 

 Herschel. De Vico, the Director of the Observatory at the 

 Collegio Romano, announced in the beginning of the year 

 1839, that he had discovered three other stars in the trape- 

 zium with his great Cauchoix refractor. These have not 

 been observed either by Sir John Herschel or Mr. Bond. 

 That portion of the nebula nearest the almost unnebulous 

 trapezium, and forming, as it were, the anterior part of the 

 head above the throat, the regio Huygeniana, is speckled, and 

 of a granular texture, and has been resolved into clusters of 

 stars both by Lord Rosse's colossal telescope and by the large 

 Cambridge (U.S.) refractor.' Many positions of the smaller 



w Sir John Herschel, in the Memoirs of the Astronomical 

 Society, vol. ii. 1824, pp. 487-495, pi. vii. viii. The latter 

 of these gives the nomenclature of the separate regions of the 

 nebula in Orion, which have been explored by so many 

 astronomers. 



67 Delambre, Hist, de VAstron. modernc, torn. ii. p. 700. 

 Cassini reckoned the appearance of this fourth star ( u aggi- 

 unta della quarta stella alle tre contigue,") among the changes 

 which had taken place in the nebula of Orion in his time. 



68 " It is remarkable, however, that within the area of the 

 trapezium no nebula exists. The general aspect of the less 

 luminous and cirrous portion is simply nebulous and irrcsolv- 



, but the brighter portion, immediately adjacent to ikp 



