E 1894] Animal Mechanics. 557 
| : tion of energy to animal and vegetable physiology, which 
5 have recently been made, are of great assistance in giving 
clear and correct notions in regard to the economy of living be- 
ings, and we learn that the materials used in the constructive 
| processes of plants and animals are not of greater importance 
: than the motive power required to convert them into living 
substances. 
The law of the conservation of energy has revolutionized 
| modern physies, and the industries have been directly bene- 
fited by its applications, and its influence in agriculture when 
rightly applied, can hardly be overestimated. Faraday pro- 
| nounced it “the highest law in physical science which our 
| faculties permit us to perceive," and it has been claimed to be 
the most important discovery of the present century. 
Energy has been defined as “the power of doing work, or 
overcoming resistance." Its familiar manifestations we call 
heat, light, motion, electricity, etc. "These different forms of 
energy are mutually convertible, without gain or loss, or, in 
other words, the energy of the Universe is a constant quantity 
that is neither increased or diminished by the transformations 
it undergoes. 
All forms of energy may be transformed to heat, and this 
furnishes a convenient unit or standard for measuring it. The 
unit of heat is the amount required to raise one pound of 
water one degree in temperature. Its mechanical equivalent 
is 772 foot-pounds, which is the unit for measuring work. 
‘That is to say, the heat required to raise one pound of water 
one degree in temperature, is equivalent to the force required 
toraise a weight of one pound 772 feet, or a weight of 772 
pounds one foot, which is, conveniently expressed, as 772 foot- 
pounds, the weight in pounds being multiplied into the dis- 
tance in feet through which it is raised. Foot-pounds divided 
by 2000 will give the result in foot-tons, which is often used. 
When a weight of one pound is raised 772 feet, it represents, 
in that position, 772 foot-pounds of potential, or stored energy, 
and when this weight is allowed to fall the entire distance 
without interruption, the stored energy is transformed into 
active energy or motion, and when this motion is arrested on 
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