184 HISTORY OF PHYSICAL ASTRONOMY. 



Thus it is impossible that an assertion, false to any amount which 

 the existing state of observation can easily detect, should have any 

 abiding prevalence in astronomy. Such errors may long keep their 

 ground in any science which is contained mainly in didactic works, 

 and studied in the closet, but not acted upon elsewhere ; which is 

 reasoned upon much, but brought to the test of experiment rarely or 

 never. Here, on the contrary, an error, if it arise, makes its way into 

 the Tables, into the Ephemeris, into the observer's nightly List, or his 

 sheet of Reductions ; the evidence of sense flies in its face in a thousand 

 observatories ; the discrepancy is traced to its source, and soon disap- 

 pears forever. 



In this favored branch of knowledge, the most recondite and delicate 

 discoveries can no more suffer doubt or contradiction, than the most 

 palpable facts of sense which the face of nature offers to our notice. 

 The last great discovery in astronomy the motion of the stars arising 

 from Aberration is as obvious to the vast population of astronomical 

 observers in all parts of the world, as the motion of the stars about the 

 pole is to the casual night wanderer. And this immunity from the 

 danger of any large error in the received doctrines, is a firm platform 

 on which the astronomer can stand and exert himself to reach perpet- 

 ually further and further into the region of the unknown. 



The same scrupulous care and diligence in recording 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 con- 

 sidered as constituting a Descriptive Astronomy ; such are, for instance, 

 Catalogues of Stars, and Maps of the Heavens, Maps of the Moon, rep- 

 resentations 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 exist many large catalogues of smaller stars. 

 Flamsteed's Historia Celcstis, which much surpassed any previous cat- 

 alogue, contained above 3000 stars. But in 1801, the French Histoire 

 Celeste appeared, comprising observations of 50,000 stars. Catalogues 

 or charts of other special portions of the sky have been published more 

 recently; and in 1825, the Berlin Academy proposed to the astrou 

 omers of Europe to carrj on this work by portioning out the heavens 

 among them. 



[2d Ed.] [Before Flamsteed, the best Catalogue of the Stars was 



