Page:Sir William Herschel, his life and works (1881).djvu/178

156 they appear in fact to exist, lying on the surface of a hollow sphere. The immediate followers of used these fixed stars as points of reference by which the motions within the solar system could be determined, or, like  and, gathered those immense catalogues of their positions which are so indispensable to the science. and alone, in England, occupied their thoughts with the nature and construction of the heavens—the one in his study, the other through observation. They were concerned with all three of the dimensions of space.

In his memoir of 1784, says:

"Hitherto the sidereal heavens have, not inadequately for the purpose designed, been represented by the concave surface of a sphere, in the centre of which the eye of an observer might be supposed to be placed.