FEEDING THE BOILER.
Some engineers claim that the most economical results can be obtained from an engine by running with the water as low as possible, consistent with safety. They hold, that, so long as the water is sufficiently high to cover the heating-surfaces, there is enough to make steam from; and the ample steam-room remaining above the water, assures a more perfect supply of dry steam for the cylinders than can be had from the more contracted space left above a high-water line. Old engineers, running locomotives furnished with entirely reliable feeding-apparatus, may be able to carry a low-water level advantageously, especially with light trains and level roads; but with ordinary men, average pumps or injectors, and the common run of roads, a high-water level is safest. With a high-water level the temperature of the boiler can be kept nearly uniform; for the increased volume of water holds an accumulated store of heat, which is not readily affected by the feed. And the surplus store is convenient to draw upon in making the best of a time-order, or in getting over a heavy grade. Then, if the pumps or injectors fail, a full boiler of water often enables a man to examine the delinquent feeding-apparatus, and set it going; whereas, with low water, the only resource would be to dump the fire.