. 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 . eet in a 1=^curve is .007, the corresponding ordinate in a curve of any other de-gree may be found with suflficient accuracy, by multiplyiug tliis deci-mal by the number tlio degree of the curve. Thus, for acurve of 5^ 36 or °, the ordinate would be .M7 X •>-6 = . ft. =- 468
. 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 . eet in a 1=^curve is .007, the corresponding ordinate in a curve of any other de-gree may be found with suflficient accuracy, by multiplyiug tliis deci-mal by the number tlio degree of the curve. Thus, for acurve of 5^ 36 or °, the ordinate would be .M7 X •>-6 = . ft. =- 468 in. For a rail of 20 feet we have ^ /^ = 100, and, consequently, ?h =-sin. D. This gives for a 1° curve, m = .0087. The corresponding or-dinate in a curve of any other degree may be found with sufficientaccuracy, l^y multiplying this decimal by the number expressing thedegree of the curve. By the above formula for m, the ordinates for curving rails in TableI, are calculated. Article II. — Reversed and Compound Curves. 30. Two curves often succeed each other having a common tangeniat the point of junction. If the curves lie on opposite sides of the com-mon tangent, they form a reversed curve, and their radii may be the!,ame or different. If they lie on the same side of the common tangcTit. tney have different radii, and form a compound curve. Thus A B Cfiff. .5) is a reversed cirve, and .1 B D % comoound curve. 16 CIRCULAR CURVES. 31, ProbleiJl. To lay out a reversed or a compound cun>e, radii or dejiection anyles and the tangent points are known. Solution. I/ay out the first portion of the curve from A to B Cfig. 5),by one of the usual methods. Find B F, the tangent to A B at thepoint B (§ 16 or ^ 21). Then B F will be tlie tangent also of the sec-ond portion B C oi a reversed, or Zi D of a compound curve, and fromthis tangent cither of these portions may be laid ofl in the usual manner A. Reversed Curves. 32 ISieOJCRi. Tlie reversing point of a reversed c
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
