. Field-book for railroad engineers. Containing formulas for laying out curves, determining frog angles, levelling, calculating earth-work, etc., etc., together with tables of radii, ordinates deflections, long chords, magnetic variation, logarithms, logarithmic and natural sines, tangents, etc., etc . widths and heights touched by diagonals. The sum of the productsin the fourth column is 247, the sum of all but the first and the last is209, and the sum of the products in the fiftli column is 186. Thesethree sums are added together, multiplied by 100, and divided by 6,according to the formula.
. Field-book for railroad engineers. Containing formulas for laying out curves, determining frog angles, levelling, calculating earth-work, etc., etc., together with tables of radii, ordinates deflections, long chords, magnetic variation, logarithms, logarithmic and natural sines, tangents, etc., etc . widths and heights touched by diagonals. The sum of the productsin the fourth column is 247, the sum of all but the first and the last is209, and the sum of the products in the fiftli column is 186. Thesethree sums are added together, multiplied by 100, and divided by 6,according to the formula. This gives the solidity of the four sections= 10700 cubic feet. 126. When the excavation docs not begin on a line at right angleslo the centre line, intermediate stations are taken where the excava-tkn b^gins on each side of tlie road-bed, and the section may be calcu- I Ob EARTH-WORK. [ated as a pyramid, having its Aertex at the first of these points, andfor its base the cross-section at the second. The preceding methodgives the same result, since w and h in this case become 0, and reduce;he foraiula to S ^^ i I w^ h^. The same remarks apply to the end ofan excavation. C. Grou7id very Irregular, 127. Prol>l€*m. To find the solidity of a section^ when the groundis very irregular. Fig. ^ution. Let A HE FE - Ar CD Bi F^ Ei (fig. 54) represent oneside of a section, the surface of -which is too irregular to be dividedinto two planes. Suppose, for instance, that the ground changes atH^ C, and Z), making it necessary to divide the surface into five trian-gles running from station to station.* Let heights be taken at /7, C,and Z), and let the distances out of these points be measured. If nowwe suppose the earth to be excavated vertically downward throughthe side line B B^ to the plane of the road-bed, we may form as manyvertical triangular prisms as tliere are triangles on the surface ThisiviM be made evident by drawing vertical planes through the sides * It will often be n
Size: 1759px × 1420px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
