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XII. On the ConJlruBion of the Heavens^ 

 By William Herfchel, Efq, F. R. S. 



Read February 3, 17B5. 



THE fubje£t of the Conftrucllou of the Heavens, on 

 wh'ch I have fo lately ventured to deliver my thoughts 

 to this Society, is of fo extenfive and important a nature, that 

 we cannot exert too much attention in our endeavours to throw 

 all poffible light upon it ; I fhall, therefore, now attempt 

 to purfue the delineations of which a faint outline was begun 

 in my former paper. 



By continuing to obferve the heavens with my lafl con- 

 ftruded, and fnice that tim.e much improved iuftrument, I am 

 now enabled to bring more confirmation to feveral parts that 

 were before but weakly fupported, and alfo to offer a few flill 

 further extended hints, fuch as they prefent themfelves to my 

 prefent view. But firfl let me mention that, if we w^ouid 

 hope to make any progrefs in an invelHgation of this delicate 

 nature, we ought to avoid two oppofite extremes, of which I 

 can hardly fay which is the moll: dangerous. If we indulge a 

 fanciful imagination and build worlds of our own, we muft: 

 not wonder at our going wide from the path of truth and 

 nature ; but thefe will vanifh like the Cartefian vortices, that 

 foon gave way when better theories were offered. On the other 

 hand, if we add obfervation to obfervation, without attempt- 

 ing to draw not only certain conclufions, but alfo conjectural 



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