MR. W. HrGGINS ON THE SPECTRA OF SOME OF THE NEBULJE. 383 



results of former telescopic observation as, in my opinion, would be of assistance to an 

 understanding of the proper significance of the new information furnished by the prism. 



[Although the detection in a nebula by the telescope of closely associated points of 

 light can no longer be regarded as a trustworthy indication that the object consists of 

 true stars, yet it is of importance to ascertain how far the classification of the nebulae by 

 the prism corresponds with the telescopic indications of their resolvability. I have 

 Lord Rosse's permission to state that the matter of the Great Nebula in Orion, which 

 the prism shows to be gaseous, has not been resolved by his telescope. In some parts 

 of the nebula he observed a large number of exceedingly minute red stars. These red 

 stars, however, though apparently connected with the irresolvable blue material of the 

 nebula, yet seem to be distinct from it. The light of these stars is doubtless too feeble 

 to furnish a visible spectrum. 



Lord OxMANTOWN has examined all the observations made at Parsonstown of those 

 nebulae which I have subjected to prismatic examination. My list contained 41 nebulae 

 which give a continuous spectrum, and 19 gaseous nebulae. 



Lord OxMANTOWN finds that these nebulae may be arranged thus : — 



Clusters 



Resolved, or resolved 1 . . . 



Resolvable, or resolvable 1 

 /Blue, or green, no resolvability 

 LNo resolvability seen . . . 



Total observed 

 Not observed . 



Continuous spectrum. Gaseous spectrum. 



10 



5 



10 6 



4 



_6 J 



31 15 



10 _4 



41 19— June 1866.] 



The numbers and descriptions of the nebulae, and their places for the epoch 1860.0, 

 included within brackets, are taken from Sir Joiiis^ F. W. Herschel's " General Cata-, 

 logue of Nebulae and Clusters of Stars"*. 



§ II. Observations of Nehuloe the Spectra of which indicate gaseity. 



[No. 2102. 3248 h. 27 H. IV. R.A. lOi' 18™ 2»-2. N.P.D. 107° 55' 50". A planetary 

 nebula. Very bright; little extended; position of longer dimension 135°; diameter 

 = 32"±; blue.] 



This nebula was observed on April 25, 1865, with a silvered glass reflector. The 

 spectrum consisted of one bright line about midway between b and F of the solar spec- 

 trum, and probably corresponding in position to the brightest of the lines of nitrogen. 



In consequence of the imperfect adjustment, at this time, of the reflector, I was 



• Philosophical Transactions, 1864, pp. 1-137. 



3g2 



