STELLAR SYSTEMS AND NEBULJE. 207 



In the early part of his career, John Herschel 

 held firmly to the views of his father of the 

 difference between star-clusters and nebulae, con- 

 sidering the latter to be composed of "shining 

 fluid." But he fell off from this view with the 

 resolution into stars of many irresolvable nebulae. 

 In 1845 William Parsons, third Earl of Rosse 

 (1800-1867), erected at Birr Castle, in Ireland, 

 his great 6 -foot reflector, which still surpasses 

 all other telescopes in point of size. With this 

 instrument Lord Rosse believed himself to have 

 resolved the Crab nebula in Taurus and the 

 Nebula in Orion, which was also said to have 

 been resolved by Bond with the 15 -inch refractor 

 at Harvard; and in 1854 Olmsted declared the 

 "resolution" of these nebulae to be the signal 

 for the renunciation of Herschel's nebular theory. 

 Most astronomers fell in with the view that all 

 the nebulae were distant clusters, which would 

 eventually be resolved into stars, although it is 

 only right to state that the Scottish astronomer, 

 John Pringle Nichol (1804-1859), and some other 

 investigators, held to the theory of Herschel. 



The solution of the great problem was in 1864, 

 when on August 29 of that year Huggins turned 

 his spectroscope on a bright planetary nebula in 

 Draco. To his amazement the spectrum was 

 one of bright lines, proving conclusively that the 



