208 



OBSERVATIONS ON NEBULiE 



M. 17; h. 2008. 



58. Sir William Herschel. " On the Construction of the Heavens." Phil. Trans. T78b, Part I. M, 

 17 is included in the enumeration of seven " very compound nebulce, or milky ways," which " cannot 

 be otherwise than of a wonderful magnitude, and may well outvie our milky way in grandeur," as 

 follows: 



The seventh is a wonderful, extensive nebulosity of the milky s kind. There are several stars visible in 

 it, but they can have no connexion with that nebulosity, and are, doubtless, belonging to our own system 

 scattered before it. It is the 17th of the Connaissance des Terns. 



Sir J. F, W. Herschel. " Observations of Nebulce and Clusters of Stars, made at Slough, with a 

 twenty feet Reflector, <|-c." Phil. Trans. 1833, Part II. 



No. Synonym. A. R. 1830.0 N. P. D. 1830.0 



Description and Remarks. 



Sweep. 



2008. 



M. 17 



18" 10"" 44^2 



46.8 



106° 17' 55' 



14 5 



51.8 



14 19 



15 48: 



15 27:: 



The principal star"" in the preceding arc of the 

 horse-shoe-like portion of the nebula M. 17. 

 See fig. 35. 



The small, insulated, resolvable knot'' in the fol- 

 lowing* strait branch of the nebula. 



The same knot. See description of this nebula in 

 the Appendix. See also the figure. 



A most curious object, not unlike the nebula in 

 Orion, (as it used to be figured, like a Greek 

 capital omega, n.) There is in it a resolvable 

 portion, or knot, distinctly separated from, and 

 insulated in the rest, as if it had absorbed the 

 nebula near it'. (A figure carefully drawn.) 

 (The P. D. inaccurate'', being much past meri- 

 dian.) 



A large extended nebula. Its form is that of a 

 Greek Q. with the left (or following) base-line 

 turned upwards. The curved (or horse-shoe) 

 part is very faint, and has many stars in it. The 

 preceding base-line hardly visible''. The follow- 

 ing, which is the principal branch, occupies nearly 

 half the field, (7^'.) Its light is not equable, but 



blotty. 



Strong twilight. 



163 



274 



358 

 33 



48 



Sir J. F. W. Herschel. "Notes on the List of Figured Nebula," in the "Appendix" to the above 



paper. 



Fig. 35, Mess. 17. — The figure of this nebula is nearly that of a Greek capital omega, n, somewhat dis- 

 torted, and very unequally bright. It is remarkable that this is the form usually attributed to the great 

 nebula in Orion, though in that nebula I confess I can discern no resemblance whatever to the Greek let- 

 ter. Messier perceived only the bright following* branch of the nebula now in question, without any of 

 the attached convolutions which were first noticed by my father.' The chief peculiarities which I have 



s Art. 18, Aug. 10. 



'» The north polar distances of these two points are, as given here, on the average, about 2' larger than mine. 



> Art. 47. 1; Art. 48. 4, 5. k Art. 49. 2. 



1 1 have not been able to find Sir William Herschel's notice of these; and perhaps they are not published, since 

 Sir J. Herschel, in another part of this paper, refers to his father's " observations of Messier's nebulae, (which," 

 he adds, " are not included in his catalogues,) »&c." 



* Two errata occur here in the Phil. Trans. In both instances, for '•' preceding " read " following." 



