NOVUM ORGANUM. 301 



mmori splendore, sed potiua illustriori et magis glorioso, quam 

 qui redditur a corpore lunae l ; neque tamen constat eas nubes 

 coaluisse in corpus densum aquae. Etiam videmus aerem tene- 

 brosum pone fenestras noctu -reflectere lucem candelae, non 

 minus quam corpus densum. Tentandum etiam foret experi- 

 mentum immissionis radiorum soils per foramen super flammam 

 aliquam subfuscam et caeruleam. Sane radii aperti solis, inci- 

 dentes in flammas obscuriores, videntur eas quasi mortificare, 

 ut conspiciantur magis instar fumi albi quam flammse. Atque 

 haec impraesentiarum occurrunt, quae sint ex natura Instantia- 

 rum Crucis circa hanc rem ; et meliora fortasse reperiri possunt. 

 Sed notandum semper est, reflexionem a flamma non esse ex- 

 pectandam, nisi a flamma alicujus profunditatis ; nam aliter 

 vergit ad diaphanum. Hoc autem pro certo ponendum, lucem 

 semper in corpore aequali aut excipi et transmitti aut resilire. 



Similiter, sit natura inquisita Motus Missilium, veluti spi- 

 culorum, sagittarum, globulorum, per aerem. Hunc motum 

 Schola (more suo) valde negligenter expedit ; satis habens, si 

 eum nomine motus violenti a naturali (quern vocant) distin- 

 guat ; et quod ad primam percussionem sive impulsionem at- 

 tinet, per illud, (quod duo corpora non possint esse in uno loco, 

 ne fiat penetratio dimensionum^) sibi satisfaciat ; et de processu 

 continuato istius motus nihil curet. At circa hanc naturam 

 bivium est tale : aut iste motus fit ab aere vehente et pone 

 corpus emissum se colligente, instar fluvii erga scapham aut 

 venti erga paleas ; aut a partibus ipsius corporis non sustinen- 

 tibus impressionem, sed ad eandem laxandam per successionem 

 se promoventibus. Atque priorem ilium recipit Fracastorius, 

 et fere omnes qui de hoc motu paulo subtilius inquisiverunt 2 ; 



1 The comparison of the brightness of the moon in the daytime with that of a 

 cloud was ingeniously applied by Bouguer to determine the ratio of the moon's light 

 to the sun's. 



2 See Fracastorius, De Sympathid et Antipaihla, c. 4. 



The notion that the air concurred in producing the continued motion of projectiles 

 is found in the Timeeus, p. 80. Plato has been speaking of respiration, of which his 

 theory is, that the expiration of air through the nostrils and mouth pushes the con- 

 tiguous external air from its place, which disturbs that near it, and so on until a circle 

 is formed, whereby, by antiperistasis, air is forced in through the flesh to fill up the 

 cavity of the chest a circulation of air through the body, in short. On the same 

 principle he would have explained a variety of other phenomena the action of cup- 

 ping instruments, swallowing, the motion of projectiles, &c. &c. All these, however, 

 after suggesting the explanation, he leaves unexplained. But Plutarch, Quasi. Platan. 

 x. (p. 177. of Reiske's Plutarch) developes a similar explanation in each case. I 

 transcribe what he says of projectiles : Ta Se f>nrTov/j.eva )8ap7j rbv aepa 



6 fie" irepififrfuv oiriffo), rep 



