A Manual of Civil Engineering

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Charles Griffin, 1872 - Civil engineering - 784 pages
 

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Page 351 - Geological Classification. The geological position of rocks has but little connection with their properties as building materials. As a general rule, the more ancient rocks are the stronger and the more durable ; but to this there are many exceptions. According to the usual geological classification, rocks are divided into igneous, metamorphic, and sedimentary.
Page 699 - ... multiplying it by the sectional area. The most convenient instrument for such measurements of velocity is a small light revolving fan, on whose axis there is a screw, which drives a train of wheel work, carrying indexes that record the number of revolutions made in a given time. The whole apparatus is fixed at the end of a pole, so that it can be immersed to different depths in different parts of the channel. The relation between the number of revolutions of the fan per minute, and the corresponding...
Page 386 - Rankine'e rule for the proportion of stones : " In order that the stones may not be liable to be broken across, no stone of a soft material, such as the weaker kinds of sandstone and granular limestone, should have a length greater than 3 times its depth. In harder materials the length may be 4 or 5 times the depth. The breadth in soft material may range from lj time to double the depth; in hard materials it may be 3 times the depth.
Page 319 - The properties of earth with respect to adhesion and friction are so variable that the engineer should never trust to tables or to information obtained from books to guide him in designing earthworks, when he has it in his power to obtain the necessary data either by observation of existing earthworks in the same stratum or by experiment.
Page 151 - Cases I. and II. (B); to a couple, as in Case III. (C); to a force, combined with a couple whose axis is parallel to the line of action of the force, as in Cases IV. and V. This can occur...
Page 280 - The contingency of the sudden application of a moving load is provided for by the factor of safety, which expresses the ratio of the proof load to the working load (Article 247). The action of the rolling load to which a railway bridge is subjected is intermediate between that of an absolutely sudden load and a perfectly gradual load. It has been investigated mathematically by Mr. Stokes, and experimentally by Captain Galton, and the results are given in the Report of the Commissioners on the Application...
Page 412 - ... by efficient drainage, one way of making provision to resist the additional pressure which may arise from such saturation is to calculate the requisite thickness of wall, as if the earth were a fluid, making if> (the angle of repose) = fc> in the formulae.
Page 389 - ... of the course, inwards from the face; but the backs of these stones may be rough. The proportion and length of the headers should be the same as in ashlar, and the
Page 411 - The objects of this are, at once to distribute the pressure over a greater area than that of any bed-joint in the body of the wall, and to diffuse that pressure more equally, by bringing the centre of resistance nearer to the middle of the base than it is in the body of the wall. The power of earth to support foundations has already been considered in Article 199.
Page 360 - ... in which case the expansion of water in freezing between the layers makes them split or scale off from the face of the stone. When it is built on its " natural bed," any water which may penetrate between the edges of the layers has room readily to expand or escape. The better kinds of sandstone are the most generally useful of...

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