Engineering and Contracting . Lei^e//ng[ ScreivlThumb Screw t!ut -A Z-4i- -^- z-4i:. Elevation. E&C. ?Frnm an article Ir Illinois Central R. R. Employes Magazine byT. H. Robertson, Assistant Engineer, Valuation Department. Protractor Device for Measuring Tunnel Cross-Section. office protractor being, set at the same distance abovebase of rail or grade as the field instrument height of protractor above base vail is recorded inthe field, as it varies on curves due to elevation of outerrail. The points platted on the cross-section sheet arejoined by lines, and the area is determined
Engineering and Contracting . Lei^e//ng[ ScreivlThumb Screw t!ut -A Z-4i- -^- z-4i:. Elevation. E&C. ?Frnm an article Ir Illinois Central R. R. Employes Magazine byT. H. Robertson, Assistant Engineer, Valuation Department. Protractor Device for Measuring Tunnel Cross-Section. office protractor being, set at the same distance abovebase of rail or grade as the field instrument height of protractor above base vail is recorded inthe field, as it varies on curves due to elevation of outerrail. The points platted on the cross-section sheet arejoined by lines, and the area is determined by the plani-meter or by calculations based on the triangles of whichthe figure is composed. The data taken are simple torecord, and can be as readily platted and computed inthe office as data taken by any other method. The actual cost of securing cross-sections of Montgom-ery tunnel, which is an unlined rock tunnel 252 ft. long,was $, or less than 2 ct. per linear foot. Six sec-tions were taken in this tunnel, averaging about 20 read-ings each. During the progress of measuring th
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicago, bookyear19
