An Elementary Course of Civil Engineering: For the Use of Cadets of the United States Military Academy

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Wiley & Putnam, 1846 - Civil engineering - 366 pages
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Page 105 - In the softer and more spongy kinds of wood the fibres, instead of being forced back longitudinally and condensed upon themselves, are, by driving a thick, and especially a rather...
Page 288 - When the axis of the roadway is laid out on the side slope of a hill, and the road-surface is formed partly by excavating and partly by embanking out, the usual and most simple method is to extend out the embankment gradually along the whole line of excavation. This method is insecure, and no pains therefore should be spared to give the embankment a good footing on the natural surface upon which it rests, particularly at the foot of the slope. For this purpose the natural surface should be cut into...
Page 285 - ... rocks, in which the strata have a dip, or inclination to the horizon, are liable to slips, or to give way by one stratum becoming detached and sliding on another which is caused either from the action of frost, or from the pressure of water, which insinuates itself between the strata. The worst soils of this character are those formed of alternate strata of clay and sand ; particularly if the clay is of a nature to become semifluid when mixed with water. The best preventives that can be resorted...
Page 83 - A long, uniform, cast-iron pillar, with its ends firmly fixed, whether by means of discs or otherwise, has the same power to resist breaking as a pillar of the same diameter, and half the length, with the ends rounded or turned so that the force would pass through the axis.
Page 288 - In side-formings along a natural surface of great inclination, the method of construction just explained will not be sufficiently secure ; sustaining-walls must be substituted for the side slopes, both of the excavations and embankments. These walls may be made simply of dry stone, when the stone can be procured in blocks of sufficient size to render this kind of construction of sufficient stability to resist the pressure of the earth. But when the blocks of stone do not offer this security, they...
Page 300 - ... objects that might obstruct the action of the wind and the sun on its surface. Fences and hedges along the road should not be higher than five feet ; and no trees should be suffered to stand on the road-side of the side drains, for independently of shading the road-way, their roots would in time throw up the road-coFering.
Page 61 - ... the other slightly electro-positive, with respect to cast iron. These results will also enable some advances to be made towards the solution of the important problem proposed by the author in his former report, viz., " the obtaining a mode of electro-chemical protection, such that while the metal (iron) shall be preserved, the protector shall not be acted on, and the protection of which shall be invariable.
Page 108 - ... the breadth at least equal to the thickness, and seldom greater than twice this dimension, and to limit the length to within three times the thickness. When the breadth or the length is considerable, in comparison with the thickness, there is danger that the block may break, if any unequal settling, or unequal pressure, should take place. As to the absolute dimensions, the thickness is generally not less than one foot, nor greater than two ; stones of this thickness, with the relative dimensions...
Page 47 - Most forest trees arrive at maturity between fifty and one hundred years, and commence to decline after one hundred and fifty or two hundred years. The age of the tree can, in most cases, be ascertained either by its external appearances, or by cutting into the centre of the trunk, and counting the rings, or layers of the sap and heart, as a new ring is formed each year in the process of vegetation. When the tree commences to decline, the extremities of the old branches, and particularly the top,...
Page 95 - Note. This last conclusion is drawn from a comparison of the results of experiment with those obtained from calculation, in which the beam is assumed as perfectly elastic. (4-.) " The effect of bodies of different natures striking against a hard, flexible beam, seems to be independent of the elasticities of the bodies, and may be calculated, with trifling error, on a supposition that they are inelastic.

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