. Building and repairing railways . vation of thevalleys, and will take the elevation of spurs *from the divides, also plat the contours f of the country at difficultpoints when the country isunsettled and no gov-ernment survey hasbeen made, the methodwill differ somewhatfrom the foregoing. Insuch case the engineermust secure the eleva-tion and distance of thecontrolling points, whilein the former case theplats supplied him withthe distances. In addi-tion to the instrumentsspecified he will need apedometer (Fig. 10);and an odometer (, 11B, 11C), and agood watch. He will
. Building and repairing railways . vation of thevalleys, and will take the elevation of spurs *from the divides, also plat the contours f of the country at difficultpoints when the country isunsettled and no gov-ernment survey hasbeen made, the methodwill differ somewhatfrom the foregoing. Insuch case the engineermust secure the eleva-tion and distance of thecontrolling points, whilein the former case theplats supplied him withthe distances. In addi-tion to the instrumentsspecified he will need apedometer (Fig. 10);and an odometer (, 11B, 11C), and agood watch. He willnot need to be providedwith instruments for determining latitude andlongitude, for the problem has already been re-duced to sections. For example, after makingthe summit of one divide, his problem is to cross *A spur is a ridge extending from a divide and separatesthe water-sheds of two branches of the same river. fThe contour of a country is Indicated by lines laid down ona map showing the location of points of the same Fig. 10. a pocket instrument which recordsthe distance the person carrying it haswalked. In reality it records the num-ber of steps taken, but by proper ad-justment the distance traveled is in-dicated. 54 BUILDING AND REPAIRING RAILWAYS. the next valley and reach the summit of thenext divide, using the desired grade and curva-ture. Any errors of dis-tance made from one di-vide to another will notaffect those beyond. Inmaking such surveyscamp outfits are neces-These should be asand simple as pos-If the country isand sparsely set-the engineer willprobably take two ponies,one to carry his appli-ances, and the other toride. When possible he
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectrailroa, bookyear1901
