THE HERSCHELS AND THE STAR-DEPTHS. 23 



they are observed in each instance is not sufficiently 

 powerful to resolve them into stars. Sir John Herschel 

 himself, notwithstanding that tendency to reverence 

 his father's dicta which has seemed so reprehensible to 

 one biographer, was disposed to entertain the same 

 opinion ; for he says, " it may very reasonably be 

 doubted whether there is any essential physical dis- 

 tinction between" clusters of stars and those nebulso 

 which his father regarded as composed of a shining- 

 nebulous fluid, and whether such distinction as there is 

 " be anything else than one of degree, arising merely 

 from the excessive minuteness and multitude of the 

 stars, of which the latter, as compared with the former, 

 consist."'* 



But during Sir John Herschel's researches in the 

 southern heavens, evidence of a very significant nature 

 was obtained concerning this very question. I do 

 not hesitate, indeed, to say that the facts now about 

 to be described throw more light on the question of 

 external Milky Ways than any which astronomical 

 observation has yet revealed. 



In the southern skies there are two strange patches 



* Lest I should seem to dwell unduly here on the mistakes of 

 men so eminent as Professor Grant and Sir John Herschel, I" quote my 

 own opinion as recorded in 1865, in my treatise on Saturn, published 

 on the same subject. After defining ' Herschel's Nebular Theory,' I 

 said, respecting it, that 'modern discoveries do not favour it. It 

 appears probable that with sufficient telescopic power, all nebulae would 

 be resolvable into stars.' Scarcely had these words been published 

 when I received from Dr. Huggins the account of the spectroscopic 

 discovery that the Orion nebula, and several others, are composed of 

 glowing gas. 



