Without working in a tube.-Effects produced by a two-bladed screw-propeller, similar to the common screw, in diameter 13 inches and 20 inches pitch, area 1 square foot, but having a portion of the interior of its blades cut away in hollow curves,-176 lbs. Without working in a tube.-Effects produced by a two-bladed screw-propeller, 13 inches diameter and 20 inches pitch, but tapered at the outer extremities of the blades in a parabolical form thus:-137 lbs. Area of circle 1 square foot. The above experiments were varied in many ways both in speed and depth; but the mean pressures which are given are sufficiently approximate. The greatest result is given by the curved-bladed propeller. Apparatus for trying the resistances of different Screws when immersed at similar depths On the Quantity of Heat developed by Water when rapidly agitated. My last paper, communicated to the Mechanical Section of the British Association at Cheltenham, in August 1856, contained a brief notice of the experiments which had been made upon this subject by Count Rumford, and by Mayer, Joule, Thomson, Rankine, &c. The mechanical equivalents which were estimated by those philosophers therefrom, and the heat developed by chemical as well as by mechanical action, were briefly noticed; and the causes which led to the making the experiments were shown to have originated in the development of heat observed by me in the sea in stormy weather, and when water ran through sluices at Southampton Dock and other confined apertures. As formerly stated, the experiments were made by agitating rapidly a mass of 437 lbs. of well-water confined in a cubical box, until its temperature became elevated from 59° Fahrenheit's thermometer to 10310 by the same scale, but without adding the loss of heat by the radiation of the mass; thus proving the correctness of the theory, namely, that water, like other fluids, was subject to the same laws as govern chemical or mechanical action; and that friction or agitation was neither more nor less than a disturbance of molecular equilibrium, which, by deranging from their natural positions the particles of bodies, developes heat and electricity, according to the constitution of the bodies subject to their action, and to the rapidity with which those operations were performed. Encouraged therefore by the facts elicited by the experiments of last year, I undertook this year a new series of experiments, the objects of which were, 1st. To prove the accuracy or not of the last year's experiments. 2nd. The law, or approximation to it, of increased temperature. 3rd. The possibility of attaining the boiling-point. 4th. The mechanical equivalent of heat to mechanical power. For these purposes an entirely new apparatus was prepared. It was driven by the steam-engine as before. DESCRIPTION OF THE APPARATUS FOR CHURNING WATER. The apparatus consisted in the first new series of experiments of a cubical deal box, 28 inches square and 23 inches in depth. It was covered with a lid of the same material, fitted to prevent the water from escaping while in motion, and was perforated with a circular hole in the middle of the lid, to allow the working freely of a vertical axis or spindle. The spindle itself, which was 24 inches square, was furnished with eight radial arms, fitted with a series of vertical stirrers nailed upon their sides, to break the water as much as possible; and to prevent rotary motion in the water, vertical boards were fixed in the corners of the box. The axle was supported in two bearings above the box, and had no bottom spindle as in the former experiments, an objection which was urged last year. On the contrary, the bottom of the vertical axis was 3 inches above the bottom of the box. It is clear, therefore, whatever heat might have been generated by the friction of the bearings of the vertical axle could not be communicated to the water, and such was found to be the case. The whole apparatus was of wood. The box, when filled, contained 50 gallons or 500 pounds of well-water, previous to the apparatus being set in motion on the 19th of June, 1857; the following were the results of a preliminary trial : Time. : THIRD SERIES OF EXPERIMENTS.-June 19, 1857. Temp. of water in box. о 61.0 60.5 62.5 " 3 30 64 66 Temperature of water in box increased from 60°.5 to 73°. Increase in 9 hours 13°5 Total increase in 9 hours 21°.2 or 2°.35 per hour. Total increase 21°.2 50 gallons of water at starting. 42.5 gallons of water at stopping. THIRD SERIES OF EXPERIMENTS.-June 20, 1857. Result of second day (9 hours), heating water by churning. Temperature of water in box increased from 64° to 92°. Increase in 9 hours 28° . go Total increase 37° Total increase of temperature in 9 hours 37°, or 4°.1 per hour. 50 gallons of water. THIRD SERIES OF EXPERIMENTS.-June 22, 1857. Result of third day (8 hours), heating water by churning. Temperature of water in box increased from 56° to 83°. Increase in 8 hours 27° Loss from radiation in 13 hours 13°, or 1° per hour. 8 hours at 1° per hour. 8° Total increase 35° Total increase of temperature in 8 hours 35°, or 4°.375 per hour. 50 gallons of water at starting. 45 gallons of water at stopping. THIRD SERIES OF EXPERIMENTS.-June 24, 1857. Temperature of water in box increased from 72° to 104°. Increase in 11 hours 32° Loss by radiation in 13 hrs. 2o, or '0153° per hour. 11 hours at 0153° per hour 1°-6 Total increase 33°.6 Total increase of temperature in 11 hours 33°.6, or 3°.05 per hour. THIRD SERIES OF EXPERIMENTS.-June 25, 1857. Temp. of water Temp. 68 Box covered with hair-felt on previous night, to prevent radiation as much as possible. 38° Temp. of water in box increased from 102° to 140°. Increase in 13 hours Total increase of temperature in 13 hours 58°-28, or 4°.483 per hour. 50 gallons of water. 70A.M. FIRST SERIES OF EXPERIMENTS.-June 26, 1857. 58°.28 62 7 45 A.M. second-motion belt broke : started again 8 A.M. 124 10 " 9 5 A.M. Glass tube in which thermometer was placed broke, carrying thermometer into box; defect made good; started again 10 15 A.M. Temp. of water in box increased from 122° to 144°. Increase in 13 hours. 22° Loss by radiation in 11 hrs. 18°, or 1o-63 per hour. 13 hrs. at 1°-63 per hour. 20°∙19 Total increase of temperature in 13 hours 42°.19, or 32°-45 per hour. 50 gallons of water. SECOND SERIES OF EXPERIMENTS.-July 14, 1857. Result of seventh day's trial.—Apparatus for heating water in small box. Temperature of water in box increased from 68° to 118°, or 50° in 5 hours. Loss from radiation in 13 hours 22°, or 1°69 per hour, 8°45 in 5 hours. Total increase of temperature of water in box 58°45. 42°.19 Total increase of temperature of water in 5 hours 58°45, or 11°69 per hour. 236 04 revolutions per minute. The churning. box on this trial was entirely covered with hair-felt, and stood upon four glass pillars 2 inches high. This was placed in an outer box; the inner or churning-box being stayed with glass props to prevent radiation by coming in contact with the outer box, or from moisture which might accumulate in bottom of same. 1857. 13 The iron wheel driving churn-spindle (wood) was also covered with worsted cord, this acting as a non-conductor of heat. Time. Second Series of Experiments.—July 21, 1857. Result of eighth day's trial of 11 hours.-Apparatus for heating water. Temp. of water Temp. of in box. atmosphere. Temp. of water Temp. of in box. atmosphere. h m Time. h m о 6 30 A.M. 12 gallons of water at starting. 6 gallons of water at stopping. 178° 75° SECOND SERIES OF EXPERIMENTS.-July 25, 1857. Result of ninth day's trial of 111⁄2 hours.—Apparatus for heating water. 6 30 A.M. a temperature of 130°. Added 4 gallons of water to that in box; temperature when mixed 130°. 11 hours at work. 232 67 revolutions per minute. 10 gallons of water at starting. 75 gallons of water at stopping. THIRD SERIES OF EXPERIMENTS.-July 16, 1857. Result of tenth day's trial of 11 hours.-Apparatus for heating water. Temp. of water Temp. Time. Temp. of water Temp. * At this temperature an egg was put into the water, and the agitation was continued for five minutes, when the egg was taken out and found boiled quite hard. |