Harvesting the Sun

1896

When we sit in front of a coal fire and enjoy its generous warmth, do we realize that the heat and light of the burning coal are really sunshine that has been stored up for ages? Such is the fact. Centuries ago the sun shone on the earth, the plants and trees grew, fell, and grew again; they were covered by geologic deposits, and acted upon by great heat and pressure, until in the course of years and ages these broad layers of organic matter were transformed into coal. The coal thus represents the work done by the sunshine years ago, and when it is burned the imprisoned solar energy is loosened again.

Our system of power production depends upon this presence of energy. But coal is a wasteful source of energy. Even the best engines do not utilize over 10 per cent of the calculated energy of the heat of coal. And, besides this it is an inconvenient thing in many ways; it has to be mined, freighted and stored. Can we not find some more economical way of using the sun's energy?

During the last few years the great progress in electrical science has enabled man to utilize the solar heat in a thriftier way. During its day's work the sun draws up a large amount of water from the oceans and damp earth. By the action of its rays plant life flourishes, and plants draw from the ground and evaporate into the air large amounts of water. Thus an oak tree of average size, with seven hundred thousand leaves, lifts from the earth into the air about one hundred and twenty-three tons of water during the five months it displays its foliage. This evaporated water, sooner or later, falls as rain, and by the action of gravity begins to flow downward. Thus the great rivers are fed. Round and round incessantly goes the water lifted by the tireless sun to fall when deserted by him, and again to fall and run seaward as long as it may exist upon this earth.


Peculiar to the Locality

Some interesting discoveries have recently been made about animal life on the Hawaiian Islands. It appears that all the land and fresh water shells are peculiar to the locality. Nor is that all. Fifty-seven out of the seventy-eight species of birds, and seven hundred out of the one thousand species of insects do not exist in any other portion of the globe.