158 NOVUM OROANUM 



From this first vintage the form or true definition of heat 

 (considered relatively to the universe and not to the sense) 

 is briefly thus Heat is an expansive motion restrained, and 

 striving to exert itself in the smaller particles. 86 The ex 

 pansion is modified by its tendency to rise, though expand 

 ing toward the exterior ; and the effort is modified by its not 

 being sluggish, but active and somewhat violent. 



With regard to the operative definition, the matter is the 

 same. If you are able to excite a dilating or expansive 

 motion in any natural body, and so to repress that motion 

 and force it on itself as not to allow the expansion to pro 

 ceed equally, but only to be partially exerted and partially 

 repressed, you will beyond all doubt produce heat, without 

 any consideration as to whether the body be of earth (or 

 elementary, as they term it), or imbued with celestial in 

 fluence, luminous or opaque, rare or dense, locally expanded 



36 Bacon s inquisition into the nature of heat, as an example of the mode of 

 interpreting nature, cannot be looked upon otherwise than as a complete failure. 

 Though the exact nature of this phenomenon is still an obscure and contro 

 verted matter, the science of thermotics now consists of many important truths, 

 and to none of these truths is there so much as an approximation in Bacon s 

 process. The steps by which this science really advanced were the discovery 

 of a measure of a heat or temperature, the establishment of the laws of con 

 duction and radiation, of the laws of specific heat, latent heat, and the like. 

 Such advances have led to Ampere s hypothesis, that heat consists in the vibra 

 tions of an imponderable fluid ; and to Laplace s theory, that temperature con 

 sists in the internal radiation of a similar medium. These hypotheses cannot 

 yet be said to be even probable, but at least they are so modified as to include 

 some of the preceding laws which are firmly established, whereas Bacon s 

 &quot;form,&quot; or true definition of heat, as stated in the text, includes no laws of 

 phenomena, explains no process, and is indeed itself an example of illicit gen 

 eralization. 



In all the details of his example of heat he is unfortunate. He includes in 

 his collection of instances, the hot tastes of aromatic plants, the caustic effects 

 of acids, and many other facts which cannot be ascribed to heat without a stu 

 dious laxity in the use of the word. Ed. 



