276 THE POPULAR SCIENCE MONTHLY. 



real nature, and he expresses his opmion that all nebulae consist essen- 

 tially of clusters of stars, more or less remote. His original researches 

 were published in 1837, accompanied by figures, and they are of high 

 authority on this subject. We give Lamont's figure above. These 

 two drawings having been executed by diiferent observers with dif- 

 ferent telescopes (Lamont's refractor of nine inches ajjerture, and 

 Mason's reflector of twelve inches) will afford in the cases in whicli 

 they agree indubitable evidence as to the existence of any feature 

 shown in them. The non-existence of any feature not shown in either 

 is probable, although not certain. 



Sir John Herschel's " Results of Astronomical Observations at the 

 Cape of Good Hope" was published in 1847, and his drawing (our 

 Fig. 2), in the order of publication, belongs after Fig. 4, 

 In his first paper he describes Fig. 1 as follows : 



" The figure of this nebula is nearly that of a Greek capital omega, n, some- 

 what distorted, and very unequally bright. It is remarkable that this is the 

 form usually attributed to the great nebula in Orion, though in that nebula 1 

 confess I can discern no resemblance whatever to the Greek letter. Messier 

 perceived only the bright eastern branch of the nebula now in question, with- 

 out any of the attached convolutions which were first noticed by my father. 

 The chief peculiarities which I have observed in it are 1. The resolvable knot 

 in the eastern portion of the bright branch, which is, in a considerable degree, 

 insulated from the surrounding nebula ; strongly suggesting the idea of an ab- 

 sorption of the nebulous matter ; and, 2. Tlie much feebler and smaller knot at 

 the northwestern end of the same branch, where the nebula makes a sudden 

 bend at an acute angle. With a view to a more exact representation of this 

 curious nebula, I have at difterent times taken micrometrical measures of the 

 relative places of the stars in and near it, by which, when laid down as in a 

 chart, its limits may be traced and identified, as I hope soon to have better 

 opportunity to do than its low situation in this latitude will permit." 



This oppox'tunity was afforded him at his southern station, and his 

 Fig. 2 is accordingly much more detailed. He says of it in tlie work 

 last cited that his Fig. 1 is far from an accurate expression of its 

 shape : 



" In particular the large horseshoe-shaped arc ... is there represented as 

 too much elongated in a vertical direction and as bearing altogether too large 

 a proportion to [the eastern] streak and to the total magnitude of the object. 

 The nebulous diflFusion, too, at the [western] end of that arc, forming the [west- 

 ern] angle and base-line of the capital Greek omega (n), to which the general 

 figure of the nebula has been likened, is now so little conspicuous as to induce 

 a suspicion that some real change may have taken place in the relative bright- 

 ness of this portion compared with the rest of the nebula ; seeing that a figure 

 of it made on June 25, 1837, expresses no such ditfusion, but represents the arc 

 as breaking off before it even attains fully to the group of small stars at the 

 [western] angle of the Omega. . . . Under these circumstances the arguments 

 for a real change in the nebula might seem to have considerable weight. ' Nev- 

 ertheless, they are weakened or destroyed by a contrary testimony entitled to 

 much reliance. Mr. Mason, a young and ardent astronomer, .... whose pre- 



