548 



Marvels of the Universe 



But if resort be had to telescopes of considerable power, especially such giant instruments as 

 those employed by the Herschels, Lord Rosse, and, nowadaj's, at so many of the national observa- 

 tories of the world, it will be found that this nebulous patch, as so seen [in a humble telescope, 

 is no more than thousands of separate stars, which are easily recognizable as such, but, it may be, 



with truly nebulous matter 

 behind or around them. 



Resort to the spectro- 

 scope in the observation of 

 Nebulffi may be said to date 

 from 1864, when Sir William 

 Huggins brought it to bear 

 on a Nebula in the constel- 

 lation Draco. He found that 

 the spectrum afforded by 

 that object exhibited three 

 brilliant detached lines, and 

 he drew the inference that 

 the object in question was 

 not an agglomeration of 

 separate stars, but a concrete 

 mass of incandescent gas. 

 This deduction created no 

 inconsiderable sensation in 

 the astronomical world, for 

 up to that time it had been 

 generally taken for granted 

 that all Nebulae were nought 

 else but immense masses of 

 stars too closely compacted 

 together to be individualized 

 — a supposition powerfully 

 encouraged by Lord Rosse's 

 success in showing to be 

 unquestionably stellar nu- 

 merous objects which, up to 

 the time when his gigantic 

 Reflector at Birr Castle 

 was brought to bear on 

 them, were recognized to be 

 patches of nebulous matter, 

 the physical nature of which 

 was unknown. 



We on the Earth associate with masses of burning gas a constant variation in the intensity and 

 likewise in the visible outline of the supplies of gas in course of ignition, but there is an entire 

 absence of recorded signs of any such changes in any of the Nebulse which are now set down as 

 gaseous in their constitution. This undoubted fact cannot but be regarded as tending to militate 

 against the gaseous theory of Xebulse, notwithstanding the strong proofs which are available to 

 support that theory, which has met with general acceptance on the part of astronomers. It would 

 lead me too far afield to go into the technical details of spectroscopy in connection with Nebulae, 



Photo liil] 



IThe Lid Ohservalory. 



ed fr 



THE TRIFID NEBULA. 



its peculiar division into three distinct nebulous mas 



