1/43h 15m 1482.7 8387.1 13.82 12.57 1.26 | 34.28 |193.9 5.66 233h 30m 1992.12 11111.59 3.5 2.55 .28 58.16 331.7 5.61 3 32h 30m 1469.5 7822.23 3.5 2.73.24 45.22 240.7 5.32 Friction of Steam-engines. The difference in loss of power by friction, between beam and direct action engines is found by experiment to be so trifling, as to be unnecessary to be taken into account in estimating their relative advantages. The amount of pressure upon the piston, expended in each kind of engine in overcoming friction appears, on an average, to be not more than about 1 lb. to the square inch, in well-constructed engiues. Steam-engines for Cotton and Paper Mills. For Cotton Mills.-The best steam-engines for cotton-mills are the double-acting, working the steam expansively. The most advantageous mean pressure on the piston with low pressure steam is 5lb per circular inch, and each circular inch will suffice to drive three spindles of cotton yarn twist with the machinery. For mule yarn, add 15 to the number of the yarn, and multiply the sum by 26; the product will be the number of spindles for each circular inch of piston. Or, one horse-power will drive 100 spindles with cotton yarn, and machinery. And for mule yarn, add 15 to the number of the yarn, and multiply by 8; the product will be the number of spindles for each horsepower. One horse-power will work 12 power-looms, with the preparatory machinery.—Brunton. For Paper Mills.-A beating machine requires about 7 horse-power. The new paper machines require from 2 to 2 1-2 horse-power; 3 1-2 horse-power will prepare 1 ton old rope per week, working ten hours per day.-Fenwick. Steam-power required to drive various kinds of Ma. chinery. A series of experiments instiuted by Mr. Davison, at Messrs. Truman and Co.'s Brewery, to ascertain the power required to drive various kinds of machinery, gave the following results: 1st. That an engine which indicated 50 horses power wnen fully loaded, showed, after the load and the whole of the machinery were thrown off, 5 horses, or one tenth of the whole power. 2nd. 190 feet of horizontal, and 180 feet of upright shafting, with 34 bearings, whose superficial area was 3300 square inches, together with 11 pair of spur and bevel wheels, varying from 2 feet to 9 feet in diameter, required a power equal to 7.65 horses. 3rd. A set of three-throw pumps, 6 inches in diameter, pumping 120 barrels per hour, to a height of 165 feet, 4.7 horses. By the usual mode of calculation (viz., 33,000 lbs. lifted one foot high per minute), it would appear that there was, in this case, friction to the extent of 13 per cent. 4th. A similar set of three-throw pumps, 6 inches in diameter, pumping 160 barrels per hour, to a height of 140 feet,6.2 horses. By the same mode of calculation as before, there was here friction to the amount of 15 per cent. 5th. A set of three-throw pumps, 5 inches in diameter, raising 80 barrels per hour, to a height of 54 feet, 1 horse. - By calculation as before, the friction amounted to 12 1-2 per cent. 6th. A set of three-throw "starting" pumps, pumping 250 barrels of beer per hour, to a height of 48 feet, -4.87 horses. By calculation as before, the friction amounted to 15 1-2 per cent. 7th. Two pair of iron rollers and an elevator, grinding and raising 40 quarters of malt per hour=8.5 horses. 8th. An ale-mashing machine, made by Haigh, of Dublin; mashing at the time, 100 quarters of malt,— 5.68 horses. 9th. Two porter-mashing machines, made by More. land, mashing at the time, 250 quarters of malt, 10.8 horses. 10th. 95 feet of horizontal Archimedes screw, 15 inches diameter, aud an elevator, conveying 40 quarters of malt per hour, to a height of 65 feet,-3.13 horses. Mr. Tredgold's Estimate of the Distribution and Expenditure of the Steam in an Engine. IN A NON-CONDENSING ENGINE. Let the pressure on the boiler be Force required to produce motion of 10.000 0.070 Force required to produce motion of the steam in the cylinder The following formula has been given by Mr. Wm. Pole for calculating the pressure and density of steam for engines working expansively, which is stated to produce a very near approximation to the truth; the mean error being only .0062 lb. per square inch: Let P be the total pressure of the steam in lbs. per square inch, and V its relative volume, compared with that of its constituent water. |