965 



sures taken from the centre of the principal nucleus to the apparent 

 boundary of the spiral coils in different angles of position. A hope 

 is then expressed that, as several of these stars are no doubt within 

 reach of the great instruments at Pulkova and at Cambridge, U.S., 

 the distinguished astronomers who have charge of them will- consider 

 the subject worthy of their attention. 



The spiral arrangement of 51 Messier was detected in the spring 

 of 1845, and in the following spring an arrangement, also spiral, 

 but of a different character, was detected in 99 Messier. The author 

 considers that 3239 and 2370 of Flerschel's 'Southern Catalogue' 

 are very probably objects of a similar character ; and as the same 

 instrument does not appear to have revealed any trace of the form 

 of 99 Mcvssier, he does not doubt that they are much more conspicu- 

 ous, and therefore entertains the hope that, whenever the southern 

 hemisphere shall be re-examined with instruments of great power, 

 these two remarkable nebuljfi will yield some interesting result. 



The author briefly refers to the other spiral nebulae discovered 

 up to the present time, which are more difficult to be seen, and to 

 clusters in the exterior stars of which there appears to be a tendency 

 to an arrangement in curved branches. He then passes to the re- 

 gular cumular nebulae, in which, although they are perceived at once 

 to be objects of a very different character, there still seems to be 

 something like a connecting link. 



Among the nebulous stars two objects are stated to be well 

 worthy of especial notice— No. 450 of Sir John Herschel's Catalogue, 

 and i Orionis. A representation of No. 450, as seen with the six- 

 feet telescope, is given. It has been several times examined, but as 

 yet not the slightest indication of resolvability has been seen. The 

 annular form of this object was detected by Mr. Stoney wlien ob- 

 serving alone, but Lord Rosse has since had ample opportunities of 

 satisfying himself that the object has been accurately represented. 

 A representation of i Orionis is likewise given. The remarkable 

 feature in this object, the dark cavity not symmetrical with the star, 

 was also discovered by Mr. Stoney when observing alone with the 

 three-feet telescope. Lord Rosse has since seen it several times and 

 sketched it. A small double star n.f. i has similar openings, but 

 are not so easily seen. These openings appear to be of the same 

 character as the opening within the bright stars of the trapezium of 

 Orion, the stars being at the edges of the opening. Had the stars 

 been situated altogether within the openings, the suspicion that the 

 nebula had been absorbed by the stars would perhaps have suggested 

 itself more strongly. As it is, the author thinks we can hardly fail 

 to conclude that the nebula is in some way connected with these 

 bright stars, in fact that they are equidistant, and therefore, if the 

 inquiries concerning parallax should result in giving us the distances 

 of these bright stars, we shall have the distance of this nebula. 



The long elliptic or lenticular nebulae are stated to be very nu- 

 merous, and three sketches of remarkable objects of this class are 

 given. 



In proceeding with the re-examination of Sir John Herschel's 



