302 COSMOS. 



observations on the constellations of Andromeda, Sagittarius, 

 and Orion. He made use of an object-glass of Campani's, 

 37 feet in focal length, which was in the possession of the 

 Paris Observatory. In entire opposition to the views of 

 Halley, Lacaille, Kant, and Lambert, the intellectual John 

 Michell declared (as Galileo and Dominique Cassini had done) 

 that all nebula3 were stellar clusters, aggregations of very mi- 

 nute or very remote telescopic stars, whose existence would 

 undoubtedly be some day revealed by means of more perfect 

 optical instruments. 18 Compared with the slow progress we 

 have hitherto depicted, the knowledge of nebulous spots 

 received a rich accession of facts by the persevering industry 

 of Messier. His catalogue of 1771 contains, after deducting 

 the older nebulae discovered by Lacaille and Mechain, 66 

 which had not been previously observed. He had the merit 

 of doubling the number of the nebulous spots hitherto enume- 

 rated in both hemispheres, although his labours were carried 

 on in the ill-supplied Observatoire de la Marine (Hotel de 

 Clugny)." 



To these feeble beginnings succeeded the brilliant epochs of 

 the discoveries of William Herschel and his son. ^he former 

 began as early as 1779 a regular exploration of the numerous 

 nebulous masses with which the heavens are studded. These 

 observations were made with a seven-feet reflector. His 

 colossal forty-feet telescope was completed in 1787; and in 



18 "Those nebulaa," says John Michell in 1767, (Philos. 

 Transact, vol. Ivii. for 1767, p. 251,) "in which we can 

 discover either none, or only a few stars, even with the assist- 

 ance of the best telescopes, are probably systems that are 

 still more distant than the rest." 



19 Messier, in the Mem. de I 'Academic des Sciences, 1771, 

 p. 435, and in the Connaissance des Temps pour 1783 et 1764. 

 The whole catalogue contains 103 objects. 



