. The railroad and engineering journal . inal or permanent line of the railroad (the centerline upon which it is built), all these angles are rounded offby means of curves of various radii, as shown in Plate XL,fig. 2. The usual curve is an arc of a circle, although inone case (the Festiniog Narrow Gauge Railroad inWales) a parabolic curve has been used as being the the-oretically correct curve ; that is, the curve which opposesthe minimum resistance to the passage of a train. Even this theory, however, is acknowledged to be in-accurate as to the actual resistance encountered by thetrain ; and
. The railroad and engineering journal . inal or permanent line of the railroad (the centerline upon which it is built), all these angles are rounded offby means of curves of various radii, as shown in Plate XL,fig. 2. The usual curve is an arc of a circle, although inone case (the Festiniog Narrow Gauge Railroad inWales) a parabolic curve has been used as being the the-oretically correct curve ; that is, the curve which opposesthe minimum resistance to the passage of a train. Even this theory, however, is acknowledged to be in-accurate as to the actual resistance encountered by thetrain ; and another great objection to the general adoptionof the parabola is the difficulties which occur in running inthe curve. The curve which theoretically presents theleast difficulty, both in laying out and in hauling trainsaround it, is a circular curve, with the ends eased off byone or the other of the different methods extant. The subject of easing off the ends of curves, or, as it istermed, putting in transition curves, will be taken up. /;>./. scale a i, or its latitude, , and its departure or distanceon the scale k c as +. It takes two persons to calculate latitudes and departuresby this method with rapidity and accuracy, one to read offthe angles and distances and note the results, while theother manipulates the diagram and reads the results. Oneof the diagrams can be easily made by using a piece ofcross-section paper and a paper scale, using care to havethe zero on the paper scale at the point P, about which itturns. The advantages of plotting a line of survey by means oflatitudes and departures are the greater accuracy obtainedand the less liability to error ; also the fact that any errorthat is made in plotting one line is confined to that line, or, atany rate, does not grow larger as the work advances, fromthe fact that each line is plotted not from the one whichpreceded it, but from parallel lines. The direction of eachline is thus made entirely independent o
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Keywords: ., bookcentury1800, bookdecade1880, bookidrailroadengi, bookyear1887
