GALILEO'S TELESCOPE: COLOUR 107 



Professors, monks, and friars were as bitter revilers of 

 Galileo as they had been of Roger Bacon. The sleep 

 of ages of ignorance was so rudely broken by the 

 magical little tube he put together, that, as they rubbed 

 their eyes and saw the old world of thought dissolving 

 out of view, they cursed the disturber of their grave- 

 yard peace. 



Galileo's first telescope magnified three diameters or 

 nine times : his last magnified thirty -three diameters. 

 He could not go farther with the glass lenses then in 

 use. At thirty-eight diameters the colours, developed 

 in the passage of rays of light through glass, or by 

 what is called refraction, put an effectual stop to pro- 

 gress. Newton began where Galileo stopped. He 

 analysed a beam of sunlight into its component colours 

 as they are seen in the rainbow, or through a glass 

 prism. He came to the conclusion that "refraction 

 could not be produced without colour." He was mis- 

 taken, and the mistake of a man so eminent led the 

 whole world astray. Acting on this belief, he argued 

 that "no improvement could be expected from the 

 refracting telescope," that is, from an instrument with 

 a glass or lens at the object end of the tube to form 

 an eye that collected and focused the rays of light. 

 Colour, though thus barring the march of advancing 

 science, really indicated the path of progress. But 

 nearly two centuries elapsed before the lost road was 

 regained, and the prism of glass became a more power- 

 ful factor in revealing the wonders of distant worlds 

 than the best telescopes. However, progress was not 

 wholly barred. Colours were not developed by the 

 reflection of light from a polished surface. If, then, a 

 highly polished mirror were placed in the bottom of a 



