Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 242
rface line is run with the transit. A profile of thisline is determined, as in § 34. The levelling stations are com-monly 1 chain (100 feet) apart. Places of different level areconnected by. a gradient line, which intersects the perpendic-ulars to the datum line at the levelling stations in… … Excavations. If the road bed lies below the surface, an exca-vation is made. Let ACDB (Fig. 50) represent a cross section of an excava-tion,/a point in the middle surface line, / the correspondingpoint in the road bed, and CD the width of the excavation atthe bottom. The slopes at the sides are…
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