THOUGHTS ON NATURAL PHILOSOPHY. 31 



Visible isolated stars formed with our Sun a larger 

 but essentially similar system or " galaxy," in which 

 it was even conjectured that all members might 

 resolve round a central orb ; while nebulae were 

 other systems of suns, external galaxies, awfully 

 remote from our galaxy and from each other ; oases 

 of active energy scattered through space. The 

 demolition of this stupendous conception by later 

 researches has been advanced as supplying the only 

 instance in which astronomical discovery has failed to 

 reveal in the actual a more majestic scheme than had 

 previously been idealized in the boldest imagination. 

 While, however, the colossal reflector of the Earl 

 of Rosse was engaged> it was fondly believed, in 

 finally establishing the nebulae as clusters of faint 

 stars, the researches of Angstrom, Bunsen, Kirchhoff, 

 and others were placing upon a firm foundation the 

 principles of a new science that was shortly to enter 

 the arena, with the result of utterly confounding 

 general expectation. In the year 1672 Sir Isaac 

 Newton had shown that, upon passing a ray of sun- 

 light through a glass prism, it became separated into 

 its constituent colours, by reason of the fact that all 

 rays are deflected or " refracted " on traversing the 

 prism, but that rays of different colours are refracted 

 to different degrees. After the lapse of a century 

 and a half the study of the analysis of light was 

 resumed and the instrumental means greatly im- 

 proved by Fraunhofer of Munich; and, by the 

 labours of Kirchhoff and Bunsen, the spectroscope 

 assumed its place as a powerful instrument of 

 research about the year 1860. 



