Catalogue of the Mechanical Engineering Collection in the Science Division of the Victoria and Albert Museum, South Kensington, with Descriptive and Historical Notes (Volume 2) - Softcover

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This historic book may have numerous typos or missing text. Not indexed. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1908. Not illustrated. Excerpt: ... levels where their high first cost is more than compensated for by greater durability and low cost of upkeep. Water-tight masonry is used also in passing through water-bearing strata. Iron and steel are used for the same services and have the further advantages of small bulk and weight in proportion to strength and the possibility, in the case of steel props and caps, of use elsewhere; the advancing price of timber is leading to a greatly increased use of metal. The form of support depends to a great extent on the nature of the pressure met with. In shafts pressure is met, in the case of timber, by rectangular sets or frames, closely spaced or with distance pieces, and having boards or poles behind when necessary to prevent loose ground falling in (see Nos. 1042-3). In metal, the frames are circular or the lining is of continuous cast iron segments. In levels, pressure may be met with in all directions, when a complete frame specially jointed becomes necessary (see No. 1060). In metal, curved frames are sometimes substituted for the usual trapezoidal shape. In working places, logs placed upon one another, two by two, crosswise, form efficient supports. The square-set timbering so largely used in the United States consists in framing timbers in rectangular cells (see No. 1061). Haulage and Hoisting.--Only those appliances exclusively used in mines are included in this section; others are placed with transport and lifting machinery (see Catalogue, Part I.). The common method of bringing a mineral to the surface is by means of a rope winding on a drum. Many forms of power are used for actuating it (see Nos. 1078-86) necessitating some framework over the shaft for supporting the guide pulleys. The pit head frame is usually of timber (see No. 1093) but where wi...

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