International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 355
d were used for backsights. Firstan intersection was made, large plugs (G inches square)being used. The tangent KM was then repeatedly run, J44 RAILROAD CONSTRUCTION. and each line marked on the plugs O and P, Fig. 431, withtacks, each one of which was numbered, as shown in thefigure. The lines… … run an equal number of times, and each intersection on theline O P\ Fig. 432, marked on the plug Q with a tack andnumbered. The mean of these intersections, as indicatedby the heavy line, was taken as final. Equally great difficulty was experienced in locating theP. C. and P. T. The distance was…
Railroad engineering
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