42 LIGHT SCIENCE FOR LEISURE HOURS. 



away the ' heaven of the fixed stars,' until the immensity 

 of the universe grew so great beneath their labours, 

 that new modes of expressing its dimensions had to be 

 adopted. They were not satisfied with the obvious 

 circumstance that the stars seem to remain unchanged 

 in position as the earth sweeps round the sun. They 

 tested this apparent fixity of position with instruments 

 of greater and greater power, yet always with the 

 same result. They made observations ten, twenty, 

 even fifty times more exact than Tycho Brahe's, and 

 the fact that they still detected no change of position 

 signified nothing less than the universe of the fixed 

 stars is ten, twenty, even fifty times farther from us 

 than Tycho Bralie had imagined. 



Thus when Sir W. Herschel began the noble series 

 of researches amid the stellar depths which has rendered 

 his name illustrious, the world of stars was already 

 of inconceivably enormous extent. Yet so widely did 

 he increase our appreciation of the vastness of the 

 universe, that it has been thought no exaggeration to 

 say of him, that ' he broke through the barriers of the 

 heavens : ' ' Caelorum perrupit claustra,' says his monu- 

 ment at Upton, and every student of astronomy who 

 has carefully examined Herschel's labours understands 

 the justice of the expression. For consider what 

 Herschel did. When he began his survey of the 

 heavens, astronomers had proved indeed that the nearest 

 of the fixed stars lie at enormous distances from us, and 

 some of the more advanced thinkers had begun to form 

 noble speculations respecting the relations of the stars 



