LAWS OF CALORIC. 45 



egg is ever hatched, without a due supply of 

 warmth : that as the thermometer rises in spring, 

 so does the sap of plants ; and as the mercury 

 mounts up in summer, the forces of life augment, 

 but decline in autumn, and are wholly arrested 

 during winter : that as the annual rings of trees 

 correspond in thickness with the mean tempera- 

 ture of the growing season in the higher lati- 

 tudes, and are always thickest on the side ex- 

 posed to the sun, the germination, growth, and 



cognized by Milton, who represents the sun as both eye and 

 soul of this great world, 



" Toward which the planets 

 Turn swift their various motions, or are turn'd 

 By his magnetic beam, that gently warms 

 The universe, and to each inward part, 

 With gentle penetration, though unseen, 

 Shoots invisible virtue, e'en to the deep." 



(Paradise Lost, b. iii.) 



When rightly understood, caloric is capable of explaining all the 

 phenomena of attraction, repulsion, and planetary motion ; but 

 these will not explain the operations of chemistry, geology, 

 meteorology, vegetation, and animal life ; nor the generation of 

 steam, which has become so important an agent in spinning and 

 weaving our fabrics, propelling boats, ships, and carriages, work- 

 ing mines, and in nearly all the most useful arts. But we cannot 

 expect to comprehend fully the modus operandi of caloric in 

 any one class of phenomena, until we rise high enough to survey 

 the whole field of knowledge, and to perceive the intimate con- 

 nexion between all its various branches. It was truly observed 

 by Mr. Hume, that " the only expedient from which we can hope 

 for success in our philosophical researches, is to march up directly 

 to the capital or centre of the sciences, which being once mas- 

 tered, we may everywhere else hope for an easy victory." 



