NOTES. Vll 



quibus rursus qufedam viridiori lumine cseteras preecellunt" (Hugeni 

 Cosmotheoros, ed. alt. 1699, Lib. ii. p. 114). Huygens supposes, however, 

 that there is much storm aud rain in Jupiter, for " ventorum flatus ex ilia 

 nubium Jovialium mutabili facie cognoscitur" (Lib. i. p. 69). The reveries 

 of Huygens respecting the inhabitants of the distant planets, which were not 

 worthy of a severe mathematician, have been renewed unfortunately by 

 Immanuel Kant in his excellent work, Allgemeine Naturgeschichte und 

 Theorie des Himmels, 1755 (S. 173192). 



(^) p. 21. Laplace, (des Oscillations de 1' Atmosphere, du Flux solaire et 

 lunaire,) in the Mecanique celeste, Livre iv. ; and in the Exposition du Syst. 

 du Monde, 1824, p. 291296. 



(3 9 ) p. 21. "Adjicere jam licet de spiritu quodam subtilissimo corpora 

 crassa pervadente et in iisdem latente, cujus vi et actionibus particulae 

 corpornm ad minimas distanlias se mutuo attrahunt et contiguse factse 

 cohserent" (Newton, Principia Phil. nat. ed. Le Seur et Jacquier, 1760 ; 

 Schol. ge'n. T. iii. p. 676). Compare also Newton, Opticks (ed. 1718), 

 Query 31, p. 305, 353, 367, and 372. (Laplace, Syst. du Monde, p. 384 ; 

 Kosmos, Bd. i. S. 56 and 74 (English edit. Vol. i. pp. 60 and x. Note 22). 



( 40 ) p. 22. " Hactenus phsenomena coslorum et maris nostri per vim gravi- 

 tatis exposui, sed eausam gravitatis uondum assignavi. Oritur utique hsec 

 vis a causa aliqua, quse penetrat ad usque centra solis et planetarum, sine 

 virtutis diminutione ; quseque agit non pro quantitate superficierum parti- 

 cularum, in quas agit (ut solent causae mechanicse), sed pro quantitate 

 materise solidse. Rationem harum gravitatis proprietatum ex phseno- 

 menis nondura potui deducere et hypotheses non fingo. Satis est quod 

 gravitas revera existat et agat secundum leges a nobis expositas" (Newton, 

 Principia Phil. Nat. p. 676). "To tell us that every species of things is 

 endowed with an occult specifick quality, by which it acts and produces mani- 

 fest effects, is to tell us nothing ; but to derire two or three general principles 

 of motion from phenomena, and afterwards to tell us how the properties and 

 actions of all corporeal things follow from those manifest principles, would be 

 a very great step in philosophy, though the causes of those principles were 

 not yet discovered, and therefore I scruple not to propose the principles 

 of motion, and leave their causes to be found out" (Newton, Opticks, 

 p. 377). In an earlier place (Query 31, p. 351) it is said " Bodies act one 

 upon another by the attraction of gravity, magnetism, and electricity ; and it 

 is not improbable that there may be more attractive powers than these. How 

 these attractions may be performed, I do not here consider. What I call 



