92 THE NEBULA ABOUT 6 ORIONIS. 



regular, well-defined outline all the way to its junction with the 

 Huygenian region ; in this particular, I see it more like his early 

 drawing of 1824. 



On the preceding side of the Huygenian region, there is a 

 strongly marked boundary, reaching nearly the whole distance 

 from its southern extremity to star No. 10. This boundary was 

 confirmed to me on the night of the 17th of January, while the 

 moon was shining brightly in the immediate neighbourhood of 

 the nebula. On comparing the sketch which I then made of it 

 with the ancient figures of Picard, Huygens, and Le Gentil, they 

 appeared less objectionable than one would have supposed possi- 

 ble without such a trial. 



The Nebula Oblongata, which lies entirely south of a line join- 

 ing the stars No. 76 and No. 93, divides on the following side 

 into two branches. One of these branches curves towards, and 

 apparently terminates near, the star No. 93 ; the other inclines 

 southward, and connects with the Proboscis Minor. In the pre- 

 ceding direction, it can be traced to a junction with the nebula 

 encircling the star No. 60. 



The stars Nos. 10, 12, 26, and 27 mark the present boundaries 

 of the Huygenian region, on the preceding and following sides, 

 very accurately. Provided they are not physically connected with 

 the nebula, they will serve as excellent landmarks for future com- 

 parison in regard to any change of form or position, should it 

 take place. 



No. 10 is situated close on the preceding edge of this bright 

 region, and is closely followed almost in the same parallel by 

 No. 12, a star of the seventeenth magnitude, the latter being 

 within the boundary. 



No. 27 is, as nearly as it is possible to determine with our 



