. 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 . A D E F B, measure the angles C A D, ND E,P E F, RFB, and S B V, observing to note those angles as mimts whichare laid off contrary to the general direction of these angles. Thus thegeneral direction of the angles in this case is to the right; but theangle PEF lies to the left oi DE produced, an
. 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 . A D E F B, measure the angles C A D, ND E,P E F, RFB, and S B V, observing to note those angles as mimts whichare laid off contrary to the general direction of these angles. Thus thegeneral direction of the angles in this case is to the right; but theangle PEF lies to the left oi DE produced, and is therefore to bemarked minus. The angles to be measured show the successive changesof direction in passing from one tangent to the other. Thus C A D6hov/s the change of direction between the first tangent and A D,ND E shows the change between A D produced and D E, P E F thechange between DE produced and E F, R FB the change between£Fproduced and FB, and, lastly, SB Fthe change between B F ])ro- MISCELLANEOUS PROBLEMS. 53 duccd and the second tangent. But the iing^lc of intersection (§ 2)shows the change of direction in passing from one tangent to another,and it must, therefore, be equal to the sum of the partial changesnaeasuved, that is, 13^ / = CA D -\- y DE - PEF-^ IIFB + SB V. Fig. 26. II. To determine the tangent points. This will be done if we findthe distances .1 Cand B C; for then any other distances from Cmaybe found. It is supposed that the distance A B, or the distances A Z),DE, E F, and FB have been measured. Tf one line A B connects A and B. Jind A C and B C in the triangleABC. For this purpose we have one side A B and all the angles. Jf a broken line A D E F B connects A and B, let fall a perpendicularB G from B upon A C, produced if necessary, and find A G and B Qhy the usual method of working a traverse. Thus, if A C is taken as ameridian line, and D /v, E L, and FM are drawn parallel to A C, andD H, E K, and FL are drawn parallel to B G, the difference of
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectrailroadengineering
