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these questions of doubt, is supplied by the spectroscope. 

 Spectral analysis, from the scientific point of view has 

 great significance as a means of determining the orbits 

 of the stars and their rate of movement. Some pairs were 

 so closely united that the strongest telescopes could not 

 distinguish them, and here the spectroscope stepped in 

 and settled the dispute, not only deciding the existence 

 of a double-star but even defining the time required in 

 its mutual revolutions. And brilliant further possibilities 

 lie ahead in the spectral analysis of the stars, since the 

 dark lines formed amongst the decomposed colours of 

 the spectrum, enable us by their shifting to calculate mo- 

 vements amongst the heavenly bodies so trifting as to lie 

 utterly beyond any other means of detection. 



To what cause is owing the curious colour of the 

 double stars is a question which remains undecided to 

 the present day. William Stroove was of opinion that 

 the heavenly bodies have no definite colour, but emitting 

 rays of all colours appear to shine with only the predo- 

 minating hue; at the same time he affirms that if all 

 the colours are emitted in equal proportions the effect is 

 white. 



Many astronomers suppose that various colours in 

 stars are the result of varying degrees of incandescence. 



Doppler thinks that the colour of a star depends upon 

 the velocity of its movement and its distance from the 

 earth. The intensity of colour is deepened by proximity. 

 The hue changes from white to green, from green to 

 blue, from blue to violet. The effect of increased distance 

 is to reduce intensity; the colour scale passes from white 

 to yellow, from yellow to orange, from orange to red. 

 This scientist applies the principle of light- waves to the 

 phenomena of star-colours. 



The spectral analyses of single stars by Fogel furni- 

 shed three spectra. Red and orange stars gave a spectrum 

 with numerous dark stripes: Yellow-stars, one like our 

 own sun's; white stars shewed a preponderance of blue. 

 From this Fogel inferred an abundance of metal in the first 



