WATER-POWER WITH HIGH PRESSURES AND WROUGHT-IRON WATER-PIPE. By HAMILTON SMITH, JR., M. Am. Soc. C.E. METHODS OF CONDUCTING WATER AND TRANSMITTING POWER. A description of the mode of using water-power for driving the North Bloomfield tunnel in California, some years since, will give a good illustration of some of the advantages of the hurdy-gurdy. This tunnel was originally about 8,000 feet long, through a slate highly metamorphosed, with its general line passing under a good-sized stream, at a depth of about 190 feet. There were eight working-shafts, each about 200 feet deep, which, with the lower entrance or portal, gave sixteen working faces. Diamond drills were used at the lower heading requiring power; the other fifteen headings were driven by hand-work. It was uncertain how much water would be encountered; but from the location, it was evident that a large quantity might be struck in any shaft, and hence it became necessary to have ample power at hand at each opening, in readiness for such an emergency. A pipe main was laid along the general line of the tunnel, with its pen-stock 285 feet vertical above the surface at the upper shaft, and 549 feet above the lowest shaft. It was made of single riveted sheet-iron, of No. 14 (Birmingham) gauge, in lengths of 20 feet, put together stove-pipe fashion, with the joints made tight by cloth tarred strips and pine wedges. This pipe had a diameter of 15 inches at the pen-stock, diminishing from this to 13, 11, and 7 inches at its lower end. From it, short branches, 7 inches in diameter, were extended to the several shafts. It was in one place carried across the stream by a light suspension bridge, some 150 feet long, the trunk of a tree on each side forming a convenient tower. The aggregate length of the main and branches was 9,960 feet, with some 2,500 feet additional, for the branch to the diamond drills. The pipe was laid on the surface of the ground, its only protection being in places a couple of 1½-inch planks tacked together, and placed over it; the range of temperature was from 10 degrees to 107 degrees Fahr. (in the shade). It was inspected by the foreman of the tunnel-work as he daily walked over the line; besides the occasional driving of a few wedges and putting on a band or two, it gave no trouble from leakage, which probably for its entire length did not amount to more than an average of 3 or 4 cubic feet a minute; from time to time, a little sawdust was put into the pen-stock. Three stop-gates were placed on the main, and a separate stop-gate at each shaft, operated by a fine-threaded screw, so that the water could be cut off when desired. [Illustration: FIG. 13.]