. The elements of railroad engineering . points M and A^. The curve AIN is a 6° MAPPING. 775 curve and tangent to the lines F H and H L zX. the points ofcurve J/ and N. The student will draw the tangent distances and the radiiand tangents for laying off angles in dotted lines, as theyare simply construction lines. The line of survey he willdraw in a full, bold line, as shown in the plate. The inter-section points and the points of curve and tangent aremarked by small circles, the latter being more fully describedby their station numbers. Dotted radial lines are drawnfrom the center of each cur
. The elements of railroad engineering . points M and A^. The curve AIN is a 6° MAPPING. 775 curve and tangent to the lines F H and H L zX. the points ofcurve J/ and N. The student will draw the tangent distances and the radiiand tangents for laying off angles in dotted lines, as theyare simply construction lines. The line of survey he willdraw in a full, bold line, as shown in the plate. The inter-section points and the points of curve and tangent aremarked by small circles, the latter being more fully describedby their station numbers. Dotted radial lines are drawnfrom the center of each curve to its P. C. and P. T. Onone of these radial lines the length of the radius of the curveis written, and the amount of the central angle written with-in the radial lines. The student will need no further direc-tions to enable him to plat the balance of the line and alsothe notes for Example 2, a plat of which is given in Fig. 2. 1364. Office Curves and Beam Compass.—Officecurves are curves of different radii, whose principal object. Fig. 336. is to enable the engineer to readily select a curve whichshall best fit the ground lying between tangents, as shownin the topographical map. They are commonly made ofpasteboard, each piece containing arcs of two different radii,the degrees of curvature of which, together with the scale ofeach, being distinctly written, as shown in Fig. 336. A 10°curve to a scale of 100 feet to the inch will serve for a h°curve to a scale of 200 feet to the inch, or a 2° 30 curve toa scale of 400 feet to the inch. In the same way, a 12°curve to a scale of 100 feet to the inch will serve for a G°curve to a scale of 200 feet to the inch, or a 3° curve to a 770 MAPPING. scale of 400 feet to the inch. Ofifice curves are applieddirectly to the contour map upon which a grade line hasbeen platted, and the curves fitted to ground and curves are as readily fitted as simple curves. Asatisfactory line being decided upon, the tangent distan
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
