CONSERVATION OF ENERGY.
Energy is the power to do work or overcome resistance. It is of two kinds—potential and kinetic. The former is the energy or force due to position, but it is latent or inactive. The latter is the energy of a body which is in motion. A stone resting on a mountain top, the water in a quiet mill pond, a coiled spring, are all examples of potential energy.
The stone, crushing through the cottage of a peasant, the water turning a factory wheel, the spring turning the wheels of a clock, are examples of actual or kinetic energy.
Ex.—Lay a magnet down on iron filings. They will gather in greatest abundance about the poles, and diminish toward the center, where there are none; thus showing the nature of polarity.
Energy often disappears to reappear under a different name. If we lift our hand to strike the palm of another, our vital energy becomes motion, and that in turn is changed into heat.
In the Bell telephone the sound-waves in the mouthpiece are converted into electric vibrations in the wire, and these, in turn, induce sound-waves in the receiving instrument at the other end of the line.
In dynamo-electric machines we have a chain of transmutations of force—chemical affinity in the fire-box, expansion in the boiler, becoming in turn, motion, magnetism, electric currents, until it appears as resplendent light and intense heat between the carbon points.
Potential energy slumbers in the raindrop, and, anon, as kinetic energy, flashes in the lightning.
In short, the sum of all the energies of nature is a constant quantity, although it manifests itself in a thousand different ways. The foregoing reflections indicate that the researches of modern science all point to a grand unity in God’s universe. Let us conclude by briefly referring to some instances of plan or design in the