Astronomical Notes. 189 



the S.W. showed no traces of this illusion. Procyon in the E. 

 was affected in rather a different way, the light spreading along 

 a broader segment of the ring, and oscillating to and fro. 

 This double refraction was noticed from 8h. to 8h. 30m. p.m., 

 the air being quite still and very favourable for observation, 

 excepting a slight flare in a vertical direction, which latterly 

 became horizontal, pulling out the rays on each side of the discs, 

 and giving them (if so incongruous a metaphor may be per- 

 mitted) a kind of grinning appearance. This passed away in 

 turn, and though there were traces of irregularity in Orion as 

 late as 9h., very beautiful definition succeeded. The circum- 

 stances were singularly unlike those of the previously recorded 

 mirage, that having occurred on July 27 ; this in so cold an air 

 that the thermometer marked 19° at 8h. 30m., and 15 G, 5 at 

 lOh. 30m. The complete calm, however, rendered it very 

 bearable, and the quality of the definition may be estimated 

 from the fact that I never saw the trapezium in the Great Nebula 

 of Orion so finely, and for the first time (excepting a single 

 glimpse one beautiful night) the 6th star came out occasionally 

 as a distinct, though excessively minute point. One eye-piece, 

 however, alone out of three was capable of showing it. The 

 5th star was a steady object. The grandest astronomical dis- 

 covery of the age has surely been that of the gaseous consti- 

 tution of this astonishing nebula. Ou sweeping upon a sub- 

 sequent occasion (Jan. 28th), with a power of about 30, over the 

 whole sword of Orion, while wondering at the magnificence of 

 the spectacle, I could not but be struck with the similarity of 

 aspect of all the adjacent nebulosities — that round 42 and 45 to 

 the N., and that encompassing i to the S., as well as the great 

 nebula between them. Secchi sees them all connected, as parts 

 of one extended mass, whose outlying portions are still more 

 widely spread ; and in all probability the whole of this lumi- 

 nous cloud, traceable, according to the Roman astronomer, 

 through more than 5° in a vertical, and 4° in a horizontal direc- 

 tion, may be fairly presumed to be of the same extraordinary 

 composition. The idea of incandescent gas, lying possibly in 

 advance of, rather than beyond, the stars with which it happens 

 to be optically connected, is certainly less magnificent than that 

 of a complication of stellar galaxies of incomprehensible re- 

 moteness ; but what it has lost in sublimity it may be almost 

 said to have gained in mystery. 



DOUBLE STAES. 



A little ranging about among the glories of Orion has 

 brought forward some pairs which, though small, will repay 

 the search. The first is 



127. 84 P.V. This is very near yjr 1 Orionis, which is 



