Many attempts have been made to produce power directly from the sun through solar engines, or by concentrating it in furnaces. At the St. Louis Exposition a few years ago, a Portuguese priest exhibited a solar engine called a heliophore, in which, by means of the sun's rays, the temperature was raised to 6000 degrees F., and a cube of iron placed in it melted like a snowball. The sun helps to raise the tides and some day they may be used to produce power. Many experiments are being made with both solar and tidal energy, some of them successful in a small way, but nothing that is ready to stand the test of every-day use has been devised. Doctor Pritchell says that on a clear day when the sun is high, it delivers upon each acre of the earth's surface exposed to its rays, the equal of 7,500 horse-power working continually. If the extra energy not needed for the growth of plants and animals could be used, all the work of the world could be done and the problem of fuel supply would be solved for ever. But the greatest conservation of coal possible at present lies in the use of the water-power which now goes to waste, and which, if employed, would, as we have seen, give us 30,000,000 horse-power, or more than all that is now produced from fuel by all our engines combined. Alabama offers a striking illustration of this failure to take advantage of our opportunities, for Alabama has both coal and water-power. Engineers estimate that the three principal rivers have power equal to 436,000 horse-power. At Muscle Shoals, on the Tennessee River, there is now developed 188,000 horse-power, second only to Niagara--and if the waters were conserved, the figures would reach 1,084,000 horse-power on the three rivers. This means that, according to the amount of coal required to produce each horse-power of energy, it would require 11,201,000 tons of coal each year to produce by steam as much power as these streams might easily be made to produce. Alabama, as we have said, is also a great coal state. It is now mining about 14,000,000 tons per year and only four states produce a larger amount. It will be seen that four tons out of five mined in this state will be needed to produce by steam the power that is going to waste in its rivers. The Honorable W. P. Lay, of the Alabama Conservation Commission, in calling attention to this fact, says: "Suppose for a moment that the coal fields of Alabama were sliding down an incline and pouring off over a precipice at the rate of 11,201,000 tons per year, how long would it take the people of the United States to do something to try to stop such a waste? Yet what else are we doing when we sit idly by and let the water of these streams go to waste over a precipice while we ourselves burn up the coal?" And what is true in Alabama is true to a lesser extent in most of the states. Wherever water-power is going to waste, coal is being used to take its place, and that coal is needed in some place where there is no water-power.