LIBER QUINTUS. 625 



calida? Item color es radiosi, per specula scilicet, intenduntur: 

 num etiam calores opaci (quales sunt lapidum et me tailor um 

 antequam candeant) idem patiuntur, an potius sunt luminis in 

 hac re partes nonnullae ? l Item succinum et gagates fricata 

 paleas trahunt : num etiam et ad ignem tepefacta ? Variatio 

 Experiment! fit tertio in Quanto; circa quod diligens admo- 

 dum est adhibenda cura, cum hoc multi circumstent errores. 

 Credunt enim homines, aucta aut multiplicata quantitate, pro 

 rata augeri aut multiplicari virtu tern. Et hoc fere postulant 

 et supponunt, tanquam res sit mathematics cujusdam certi- 

 tudinis ; quod omnino falsissimum est. Globus plumbeus unins 

 librae a turri demissus (puta) decem pulsuum spatio ad terram 

 descendit : num globus duarum librarum, (in quo impetus iste 

 motus, quern vocant, naturalis duplicari debet,) spatio quinque 

 pulsuum terrain feriet ? At ille ajquali fere tempore descendet, 

 neque accelerabitur juxta rationem Quanti. 2 Item sulphuris 

 (puta) drachma una, semilibrae chalybis admixta, earn fluere 

 faciet et colliquari: num igitur uncia sulphuris quatuor libris 

 chalybis ad colliquationem suflftciet? At illud non sequitur. 

 Certum enim est, obstinationem materice in patiente per Quan- 

 titatem augeri amplius, quam activitatem virtutis in agentc. 

 Porro Nimium aeque fallit ac Parum. Etenim in excoctionibus 

 et depurationibus mctallorum error est familiaris ; ut ad excocti- 

 onem promovendam, aut calorern fornacis aut additamenti 

 quod injiciunt molem augeant. At ilia supra modum aucta 

 operationem impediunt; propterea quod vi et acrimonia sua 



actually or formally hot. But the heavenly bodies, as the sun manifestly is, may be 

 hot. potestafe that is, may have the power of heating whatever is susceptible of their 

 operation. It is known that the moon's rays have never as yet been sufficiently con- 

 centrated to produce any perceptible degree of heat. 



1 The researches which Bacon here suggests, in which obscure radiant heat is dealt 

 with in the same manner as luminous heat, have been recently carried on with great 

 success, and have led to many interesting results. The question as to the nature of 

 the essential or formal connexion between heat and light remains however as yet un- 

 answered, though it may be hoped that it will shortly be satisfactorily solved. 



Telesius, of whom more than of any one else Bacon was a follower, maintained that 

 heat and light were " contubernales naturae," and that where one was present the 

 other must be present too. Bacon, with a more subtle insight into nature, proposed to 

 trace the analogy which might exist between them in cases where, sensibly at least, the 

 dogma of Telesius seemed unfounded. 



2 Long before the publication of the De Augmentis, the theory of the acceleration 

 of falling bodies, which of course includes the fact that all bodies fall from rest with equal 

 velocities (the resistance of the air being set aside), had been made known by Galileo 

 The experiments which he made about the year 1590 to show the absurdity of the 

 received opinion that the velocity of falling increases as the mass of the falling body led 

 to his leaving Pisa, where he had made them, and where he had in consequence been 

 involved in disputes with the adherents of the Peripatetic philosophy. 



VOL. I. S S 



