NOVUM ORGANUM. 241 



Fiat hujusmodi experimentum. Accipiatur spe- 

 culum 1 fabricatum contra ac fit in speculis comburentibus, et 

 interponatur inter manum et radios solis; et fiat observatio, 

 utrum minuat calorem solis, quemadmodum speculum combu- 

 rens eundem auget et intendit. Manifestum est enim, quoad 

 radios opticos, prout fabricatur speculum in densitate inaequali 

 respectu medii et laterum, ita apparere simulachra magis diffusa 

 aut magis contracta. Itaque idem videndum in calore. 



Ad 2am 5 a. Fiat experimentum diligenter, utrum per specula 

 comburentia fortissima et optime fabricate radii lunge possint 

 excipi et colligi in aliqucm vel minimum gradum teporis. Is 

 vero gradus teporis si fortasse nimis subtilis et debilis fuerit, ut 

 ad tactum percipi et deprehendi non possit, confugiendum erit 

 ad vitra ilia quae indicant constitutionem aeris calidam aut fri- 

 gidam ; ita ut radii Iuna3 per speculum comburens incidant et 

 jaciantur in summitatem vitri hujusmodi ; atque turn notetur si 

 fiat depressio aquae per teporem. 



Ad 2am 6. Practicetur etiam vitrum comburens super calidum 2 

 quod non sit radiosum aut luminosum 3 ; ut ferri et lapidis 

 calefacti sed non igniti, aut aquae ferventis, aut similium ; et 

 notetur utrum fiat augmentum et intentio calidi, ut in radiis 

 solis. 



Ad 2am 7. Practicetur etiam speculum comburens in flamma 

 coHmmni. 



Ad 2am sa. Cometarum (si et illos numerare inter meteora 

 libuerit) 4 non deprehenditur constans aut manifestus effectus in 

 augendis ardoribus anni, licet siccitates saepius inde sequi no- 

 tatae sint. Quiuetiam trabes et columnae lucidae et chasmata 

 et similia apparent saepius temporibus hybernis quam aestivis ; 

 et maxime per intensissima frigora, sed conjuncta cum siccitati- 

 bus. Fulmina tamen et coruscationes et tonitrua raro eveniunt 

 hyeme, sed sub tempus magnorum fervorum. At stellae (quas 



1 " Speculum," used for lens. Read " specillum," the common word, il passes 

 very easily into ; and probably the transition was more facile in the cursive hand. 

 8 So in the original; qy. corpus calidum. /. S. 



3 Mersenne says the greater number of the experiments mentioned in the second 

 book of the Notum Oryanum had already been made, and mentions particularly, as if 

 he had himself tried it, the reflexion of all kinds of heat by a burning mirror. He also 

 asserts that light is always accompanied by heat. De la Verite des Sciences (1625), 

 p. 210. 



4 That there was no reason for supposing comets to be more than merely meteoric 

 exhalations is the thesis maintained, and doubtless with great ability, by Galileo in 

 his Saggiatore, the true view, or at least a nearer approach to it, having been pro- 

 pounded by the Jesuit Grossi. Bacon perhaps alludes to this controversy. 



VOL. I. R 



