A Treatise On The Principles And Practice Of Dock Engineering

516 DOCK ENGINEERING. TABLE XLI. 1894. Total Amounts. Comparison in Gallons at 750 Lbs. Pressure per Square Inch. Comparison in Board of Trade Electrical Units. L. H. P. W. E. S. L. H. P. W. E. S. L. H. P. w. E. s. Capital outlay, Output,... Quantity sold, Received for supply, Average price ob- tained, £ 471,552 £ 411,018 50,729 -{ Gals. 400,313,000 332,390,000 35’55d. per 1,000 gals. Equivalent Gals. 396,256,000 333,430,000 36’51d. per 1,000 gals. Equivalent Elec. Units. 2,609,240 2,166,520 5-45d. per unit. Elec. Units. 2,582,801 2,173,298 5;6d. per unit. The actual cost of production, or station cost, was 5'17d. per 1,000 gallons of water and l'38d. per electrica! unit. Both power supplies can now be obtained at a much cheaper rate. At the present time the total cost of electricity at the switchboard, amounts to ’9d. per unit at Liverpool and to only ’35d. per unit at Newcastle, the cost of coal being, no doubt, responsible for the difference. The station cost of hydraulic power at London, in 1900, was given as 3-03d. Electric power is furnished to consumers at ld. per unit at Wigan and at l|d. per unit at several other towns, including Liverpool, at which last named place the price of hydraulic power (750 Ibs. pressure) ranges from 15d. upward. Conclusions.—Reviewing the systems as a whole, the precedence will be generally aocorded to electrical energy for convenience and adaptability, and to hydraulic energy for simplicity and control. Where a hydraulic installation is already in existence, a change to an electrical regime could scarcely be justified in this country on other than the most exceptional grounds; but where the question is an open one and unfettered by conditions, there is a slight preponderance of evidence in favour of the adoption of electricity for the transmission of power. At all events the two systems are in such general vogue—either singly or in combination—at nearly all ports as to merit sonie discussion in regard to the lines of their application and their suitability for particular classes of work. Hydraulic Machinery. —The development of hydraulic power constitutes one of the most remarkable features of the past century. From a compara- tively insignificant position, as a source of energy, water pressure suddenly and rapidly rose to a foremost place in engineering operations. Any attempt at tracing the inception and expansion of water-pressure machinery would, however, necessitate a lengthy retrogression into history, and this we cannot afford here. But it will be generally admitted that, apart from the Bramah press, the present wide range of useful applications for water power is mainly due to the ingenuity and the exertions of the late Lord Armstrong. The student who is interested in the historical aspect of