THE FORCE OF HEAT. 55 



be destroyed by the sudden catastrophe of an overwhelming 

 flood at the approach of every spring. The accumulated 

 ice and snow of the winter would be changed to vast bod- 

 ies of water as soon as they reached the temperature of 32 

 degrees; and when the boiling heat should be reached, the 

 water would change into steam with the force of an ex- 

 plosion and rend everything near it to atoms. Instead of 

 being useful to man it would be a most destructive agent, 

 which men would avoid as they would avoid nitro-glycerine. 

 The contemplation of these thoughts gives a new force 

 and interest to the fact that "the earth was given to man" 

 and truly the gift was perfectly well adapted to his uses, 

 and for his enjoyment. 



It has been shown that the force equivalent to the heat 

 required to produce 9 Ibs. of steam at 212 degrees by the 

 union of 8 libs, of oxygen and 1 Ib. of- hydrogen is equal to. 

 that represented by the fall of a ton weight down a preci- 

 pice 22,320 feet high : to change this vapor into liquid a, 

 force is exerted equal to that of the fall of a ton down 2,900 

 feet ; and to change the water into ice the force is equal to the 

 descent of a ton down 433 feet. And yet these enormous forces 

 are going on in the soil and in the tissues of delicate plants, 

 continually, silently, but omnipotently; without any out- 

 ward indication. Prof. Tyndall has remarked of this lat- 

 ent force hidden in a drop of water, "I have seen the wild 

 stone avalanches of the Alps; which thunder and smoke 

 down the declivities with a force almost sufficient to stun, 

 the observer. I have also seen snowflakes, descending so- 

 softly as not to injure the fragile spangles of which they 

 were composed; yet to produce from aqueous vapor, a quan- 

 tity of that tender material that a child might carry, 'de- 

 mands an exertion of energy competent to gather up the 

 Chattered blocks of the largest avalanche I have ever seen 

 and to pitch them to twice the height from which they 

 fell." 



Combustion is a source of heat; and the decay of organic 

 substance is a slow combustion. This fact is exemplified ir* 

 the decomposition of vegetable matter. When the farmed 



