AIDS OF THE NEWTONIAN PERIOD. 295 



the danger of any large errour in the received doc- 

 trines, is a firm platform on which the astronomer 

 can stand and exert himself to reach perpetually 

 further and further into the region of the un- 

 known. 



The same scrupulous care and diligence in re- 

 cording all that has hitherto been ascertained has 

 been extended to those departments of astronomy 

 in which we have as yet no general principles which 

 serve to bind together our acquired treasures. These 

 records may be considered as constituting a De- 

 scriptive Astronomy; such are for instance Cata- 

 logues of Stars, and Maps of the Heavens, Maps 

 of the Moon, representations of the appearance of 

 the Sun and Planets as seen through powerful 

 telescopes, pictures of Nebulae, of Comets and the 

 like. Thus, besides the Catalogue of Fundamental 

 Stars which may be considered as standard points 

 of reference for all observations of the Sun, Moon, 

 and Planets, there exists many large catalogues of 

 smaller stars. Flamsteed's Historia Celestis, which 

 much surpassed any previous catalogue, contained 

 above 3000 stars. But in 1801, the French His- 

 toire Celeste appeared, comprising observations of 

 50,000 stars. Catalogues or charts of other special 

 portions of the sky have been published more re- 

 cently ; and in 1825, the Berlin Academy proposed 

 to the astronomers of Europe to carry on this work 

 by portioning out the heavens among them (AA). 



We have already said something of the obser- 



