PORTION OF THE COSMOS. NEBULJS. 223 



Lacaille observed in the southern heavens, 14 which can 

 be perfectly resolved into true star-clusters even with 

 low magnifying powers, only 28 remain, while with more 

 powerful instruments, and greater practice and skill in 

 observing, Sir John Herschel succeeded in discovering in 

 the same zone 1500 nebula, clusters being similarly 

 excluded. 



Unaided, and unguided by any personal observation or 

 experience, and at first unknown to each other ( 374 ) although 

 tending in very similar directions, Lambert (from 1749) 

 and Kant (from 1755) exercised their imaginations, and 

 speculated with admirable sagacity on nebulosities, detached 

 galaxies, and islands of nebulae and stars sporadically dis- 

 persed in celestial space. Both Kant and Lambert were 

 inclined to the nebular hypothesis, and to the belief of a 

 process of formation continually going forward in space j and 

 even to the idea of the production of stars from cosmical 

 vapour. Le Gentil (1760 1769), long before his distant 

 voyages and disappointment in regard to the obser- 

 vation of the transit of Yenus, promoted the study of 

 nebulae by his own observations on the constellations of 

 Andromeda, Sagittarius, and Orion. He employed the 

 object-glass of Campani of 34 French feet focal length, in 

 the possession of the observatory of Paris. The sagacious 

 John Mitchell, in complete opposition to the ideas of Halley 

 and Lacaille, Kant, and Lambert, declared (as Galileo and 

 Dominique Cassini had done) all the nebulae to be clusters 

 of stars, aggregations of very small or very remote tele- 

 scopic stars, whose existence would assuredly be demon- 

 strated at some future day by the improvement of instru- 

 ments ( 375 ). A rich accession to the knowledge of nebulae, 



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