International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 347
r masonry, several feet in height, are erected at the suc-cessive points on the line, their elevation admitting of muchlonger and clearer sights. The hours of the early morningare the most favorable time for running the test line. Theair is then of uniform temperature, and the rays of the sun solow… … had by watching ones chances.Some engineers prefer to runthe surface line (if it is one con-tinuous tangent) at night, usingplummet lamps for sights. Thecenter line of the Cascade tun-nel, on the Northern PacificRailroad, was run in this way.The laying out of the surfaceline is illustrated in Fig.…
Railroad engineering
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