. 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 . d IIK = b. The slope of the sides B H or C Kis usually given bythe ratio of the base K Nto the height E N. Suppose, in the presentcase, that KN: E N ^ 3 : 2, and we-have the slope = I. Then ifthe ground were level, as D A E, it is evident that the distance from Fig. 45. the centre A to the slope
. 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 . d IIK = b. The slope of the sides B H or C Kis usually given bythe ratio of the base K Nto the height E N. Suppose, in the presentcase, that KN: E N ^ 3 : 2, and we-have the slope = I. Then ifthe ground were level, as D A E, it is evident that the distance from Fig. 45. the centre A to the slope stakes at D and E would be yl Z) = A E —M K-\- KN=^b + I c. But as the ground rises from A to Ct!irough a height C G = g, the slope stake must be set farther out adistance E G = ^ g; and as the ground falls from A to B through aheight B F =^ g, the slope stake must be set farther in a distance D F 3= 2 9- To find B and C, set the level, if possible, in a convenient positionfor sighting on the points A^ B, and C. From the known cut at thecentre find the value oi AE = ^h -{-^c. Estimate by the eye therise from the centre to where the slope stake is to be set, and take thisas the probable value of g. To A E add | g, as thus estimated, andmeasure from the centre a distance out, equal to the sum. Obtainnow by the level the rise from the centre to this point, and if it agreeswith the estimated rise, the distance out is correct. But if the esti-mated rise prove too great or too small, assume a nev.^ value for g,measure a corresponding distance out, and test the ac
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
