average, on board ship in American, British, Belgian, or French ports. WEIGHT OF A FOOT OF CAST-IRON PIPE. Wrought Iron and Steel Pipes. The following costs are subject to market fluctuations : WEIGHT PER LINEAL FOOT AND APPROXIMATE PRICES PER Ton, for WROUGHT-IRON RIVETED PIPES. £ s. d. $ £ s. d. £ s. d. 120 24 0 0 110 22 0 0 $ £ s. d. $ £ s. d. $ 19 00=95 19 6 8 96.60 19 6 8 96.60 19 6 8 96.60 18 13 4 93.30 17 13 4 88.30 17 0 0=85 For high pressures they may be made with spiral seams on a system much in favour in the United States, possessing much greater strength in proportion-as follows, the thickness of sheets being 14 gauge: TABLE OF PROPER SIZES FOR WOODEN "GRIPES," OR CLAMPS, MADE OF HARD WOOD, OF GOOD QUALITY, WITH SIZES OF THE BOLTS AND THICKNESS OF PLANK FOR DIFFERENT SIZES OF FLUMES AND Use about one-fifth Coefficient of transverse strength of a hard wood stick 1 ft. long-supported at each end, loaded in the middle-500. for safe strain. The sizes of bolts are given large; good quality of iron will be found safe at double this pressure. A stick two-thirds of the size of those in the table will hold while dry; but as they become "water soaked" they lose about one-third their strength. In practice, gripes or clamps smaller than these sizes are put upon flumes, which apparently hold all right until they become wet, when they gradually bend until they have to be removed and replaced by stronger ones. It will appear, at first sight, that the sizes given under 5 and 10 feet head are larger in proportion than those under 30 feet, but when we take into consideration the fact that a small stick will spring or bend more in proportion to its strength than a large one, the sizes will not be found too large for safety. Flumes Made of Wood.-Water may be conveyed to water-wheels and turbines by wooden flumes or box-pipes of timber, for the proportions of which the preceding table will be found useful. A highly important detail is the stoppage of drift and rubbish in the water-supply, by means of a grating in the head-race or flume. This may be made of wood or iron. If of the former, the bars should be about 3/4 inch to I inch thick and 1 inch apart, and may be about 3 inches wide, with the up-stream side of each beveled to an edge. If of iron make it of 1⁄2-inch or 5%-inch round rods, or flat rods 11⁄2 inch × 1⁄4 inch, about 1 inch apart. Set the whole grating at an angle of say 40 or 45 degrees from the horizontal and bend the upper part to a circle so that the teeth of the rake can pass through in the water-way, and cover over the part of the flume extending from the grating to the wheels. The rack should be kept clear by raking it free of weeds and rubbish occasionally. 1 |