18 AGENCY OF CALORIC IN METEOROLOGY. 



and recombination. When I come to treat of the 

 mode in which caloric produces opposite effects, 

 it will be found that in certain proportions it 

 causes the particles of ponderable matter to 

 separate, while in other proportions it forces 

 them to unite: that the aggregate force of at- 

 traction by which it tends to unite with the par- 

 ticles of gross matter, holds them together, and 

 maintains the earth in the globular form : in 

 short, that all the phenomena of nature may be 

 referred to the law by which caloric repels its 

 own particles, and attracts those of ponderable 

 matter. 



That the quantity of evaporation and rain 

 throughout the earth is in proportion to the 

 heating power of the sun, ceteris paribus, would 

 seem to be a self-evident proposition. And it 

 will be shewn hereafter from numerous scientific 

 observations i that the annual average amount 



distinctly, and rapidly, through light and resinous, or the more 

 combustible species of wood, than through such as are dense, less 

 elastic, and therefore contain less of the elastic sether termed caloric. 

 It also moves with greater velocity through water than glass, 

 and more swiftly through either than through rocks and metals, if 

 we make allowance for the greater density of the latter. For it 

 was found by MM. Biot and Colladon, that it was transmitted 

 through water at 46, at the rate of 4704 feet per second ; and 

 through cast iron at 61, at the rate of 1 1,090 feet per second. 

 But the specific gravity of cast iron is nearly eight times that of 

 water. And we shall find that it contains a far greater amount 

 of caloric around its particles than the same weight of iron, 

 although less than an equal bulk of iron. 



