. 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 . found by § 122 would be 29600 feet; whereas the method by equiva-lent sections would give the contents as before, or 1502 feet toomuch. D. Correction in Excavation on Curves129. In excavations on curves the ends of a section are not parallel * A New Method of Calculating the Cubic Contents
. 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 . found by § 122 would be 29600 feet; whereas the method by equiva-lent sections would give the contents as before, or 1502 feet toomuch. D. Correction in Excavation on Curves129. In excavations on curves the ends of a section are not parallel * A New Method of Calculating the Cubic Contents of Excavations and Embankments by the aid of Diagrams. By John C. Trautwine CORRECTION IN EXCAVATION ON CURVES. IIJ to each other, but converge towards the centre of the curve. A sectionbetween two stations 100 feet apart on the centre line will, therefore,measure less than 100 feet on the side nearest to the centre of thecurve, and more than 100 feet on the side farthest from that in calculating the contents of an excavation, it is assumed thaithe ends of a section are parallel, both being perpendicular to the chordof the curve. Thus, let figure 55 represent the plan of two sections ol. Fig. 55. an excavation, EFG being the centre line, AL and Cil/the extremeside lines, and 0 the centre of the curve. Then the calculation of tlieQrst section would include all between the lines .41 Ci and B^Di\^-hile the true section lies between A C and B D. In like manner, thecalculation of the second section would include all between HK andNP, while the true section lies between BD and L M. It is evident,therefore, that at each station on the curve, as at jP, the calculation istoo great by the wedge-shaped mass represented hy KFD^, and too Fig. 56
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
