Out from the depths of the great ugly building belch forth four gleaming, horizontal columns of water, big as barrels, with a force, speed, and roar as though the discharge were from giant cannon. Straight across the tail-race they gleam and quiver for a hundred feet, impinging upon a solid ledge of granite, in which they have worn huge caverns. The spray dashes up the face of the ledge for sixty or seventy feet. Up and down the stream, swirling and writhing in a thousand rushing, crowding whirlpools, the water, just freed from its maddening confinement, is seeking to make good its escape. But it is jammed back into the upper race, and for fifty yards you will see it hanging, ledge upon ledge, fighting, snarling, surging, and struggling for its chance to slip beneath those terrific outlet volleys and gain the lower stream and liberty and peace. The mighty Niagara has no such background of wild beauty, nor does it ever convey such an instant impression of water force. Once I saw a big two-inch plank dropped into one of those furious water columns. It seemed scarcely to touch the water, but flew, faster than the eye could follow, over to the granite ledge and was instantly smashed into ten thousand splinters, and I knew that even before the plank had reached the ledge, the mighty power which hurled it, transmuted into electricity, had already reached, and was operating, street-cars in a city seventy miles away. Come into the power-house. Look at the four gigantic generators, whirling and humming like leviathan June-bugs--see the wicked, sputtering little blue sparks from the commutators. From the windows at the back of the building we look up a very sharp slope, 1500 feet high, and see the penstocks--twenty-four-inch steel tubes, black, ungainly, and, at twilight, very uncanny. They follow in curves the profile of the rough ground, bringing the furious rush of water from the summit down to the turbines in the lower basement, turning out 26,000 horse-power. The force of the water in these penstocks is terrific. Tests of a four-inch jet from one of them have been made. A rifle-bullet glances off as from chilled steel; a jet from it, no bigger than a penholder, will drill a hole in sheet steel in a few moments. At the reservoir on the summit a fly-line may be played in the water--at the foot of the penstock no mortal could thrust a bayonet one inch into it. A United States trooper once essayed, on a wager, to cut a two-inch jet with his sword; a shattered weapon and a broken wrist resulted. In the harnessing and curbing of these mountain streams the utmost engineering skill and ingenuity has been called into play. Often the power-house has to be situated miles back in such inaccessible wilds that the greatest difficulty has been encountered in carrying machinery and supplies to the spot. At one point in the Sierras men and material were transported across two yawning chasms by means of wire cables, under which ran a freight-carrier.