This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ... to measure the speed of ships by means of two vertical glass tubes passing through the bottom of the vessel. Their lower ends were bent at right angles, the one pointing forward, the other aft. The inventor expected the water in the former tube to rise and the latter to fall, when a suitable scale would give the speed of the vessel. It was afterwards found that in an unbent tube passing through the bottom of a vessel, the water fell even lower than in the one bent backwards, none of the three pipes giving the same head as that outside, and that was what happened whenever a current of water or air flowed nearly across the opening to a pressure gauge--the gauge indicated too low a pressure. The pressure inside the nozzle being unknown, how was the theoretical power computed, from which the 80 per cent. efficiency given on p. 238 was reduced? The pressure, when the jet was closed, was of course useless for the purpose. He suggested the following method of testing the energy in a Mr. Wingfield. jet without risking the error due to incorrect readings of pressure. If the temperature was 53 3 F., 1 lb. of water was equivalent to a prism 3"3077 feet long and one square inch in section. W Hence V = 2-3077-r-, A where V denotes feet per second; W, lbs. per second; A, area of section of stream in square inches. V2 W3 Then foot-lbs. per second =----X W = 0-082697--,; W3 or foot-lbs. per minute = 4-96172--. A2 V3 Therefore the HP. of jet was nearly--. It was only necessary therefore to catch and weigh the water which issued in 5 or 10 minutes from a suitable nozzle and estimate the rate of discharge. That and the area of the jet were all the data required. If the nozzle was properly formed, there should be no perceptible contraction after the jet left it. Where there w...