LIB. II. 13. 179 



focus parvus in eodem loco, nonnihil invicem au- 

 gent calorem ; at aqua tepida immissa in aquam 

 f erven tern refrigerat 4 . 



35. Mora corporis calidi auget calorem. Etenim calor 

 perpetuo transiens et emanans commiscetur cum 

 calore prseinexistente, adeo ut multiplicet calorem. 

 Nam focus non aeque calefacit cubiculum per mo- 

 ram semihorne, ac si idem focus duret per horam 

 integram. At hoc non facit lumen ; etenim lam- 

 pas aut candela, in aliquo loco posita, non magis 

 illuminat per moram diuturnam, quam statim ab 

 initio 5 . 



36. Irritatio per frigidum ambiens auget calorem ; ut 

 in focis videre est per gelu acre 6 . Quod existima- 

 mus fieri non tantum per conclusionem et contrac- 

 tionem caloris, quoe est species unionis; sed per 

 exasperationem : veluti cum aer aut baculum vio- 

 lenter comprimitur aut flectitur, non ad punctum 

 loci prioris resilit, sed ulterius in contrarium. Ita- 

 que fiat diligens experimentum, per baculum vel 

 simile aliquid immissum in flammam, utrum ad 

 latera flammae non uratur citius, quam in medio 

 flammge. 



37. Gradus autem in susceptione caloris aunt complu- 



4 Flames consuming Oxygen accepts Heat very slowly, and re- 

 combine their strength : water, not tains it readily, and so, after remov- 

 consuming it, but being heated by ing the source of Heat the effect is 

 other means, and having no proper felt for some time; whereas on re 

 heat, when mixed at two different moving a candle, the light dies out 

 temperatures, on combination, takes almost instantaneously. 

 a mean temperature between the 6 In dry frosty weather the Oxy- 

 two. The Heat follows the Law gen is more readily detached from 

 which leads it to tend towards an the air, and also the draught of air 

 equilibrium. is quicker. Also the edges of 

 5 Light does not seem to pene- flame are the hottest, because of 

 trate the air as Heat does. There their contact with the Air which 

 is no steady augmentation of light feeds. 

 in a room, as there is of Heat. Air 



N 2 



