. The elements of railroad engineering . he preceding example, we haveE = X .18109 + 390 X .17810 = , since 2 « = 10° 26 X 2 = 20° 52 and ^^ ^f = ^ = .17810. SURVEY OF BEAVER CREEK. d 4-1 C/3 ir. c u Bearing. 1 390 384 N 1° 15 W + 10° 20 + A 201 Due E + 20° 11 B 404 S 80° 10 W - 11° 14 187 S 70° 20 W - 14° 22 D 503 S 08° 32 W + 3° 12 2 384 N 20° 15 W - 0° 10 The tables of Horizontal Distances and Differences ofElevation for Stadia Measurements are computed forobservations taken on a vertical rod held perfectly plumb. Fig. 303 shows the method of keeping sket
. The elements of railroad engineering . he preceding example, we haveE = X .18109 + 390 X .17810 = , since 2 « = 10° 26 X 2 = 20° 52 and ^^ ^f = ^ = .17810. SURVEY OF BEAVER CREEK. d 4-1 C/3 ir. c u Bearing. 1 390 384 N 1° 15 W + 10° 20 + A 201 Due E + 20° 11 B 404 S 80° 10 W - 11° 14 187 S 70° 20 W - 14° 22 D 503 S 08° 32 W + 3° 12 2 384 N 20° 15 W - 0° 10 The tables of Horizontal Distances and Differences ofElevation for Stadia Measurements are computed forobservations taken on a vertical rod held perfectly plumb. Fig. 303 shows the method of keeping sketch and notes intopographical work. 688 SURVEYING. 1302. An efficient topographical survey is one which fully serves every purpose for which it is made. Itsvalue depends more upon the accuracy of that which isrepresented rather than the minuteness or quantity ofdetail. The topographer should be able to readily and in-telligently decide between what is important and what isnot important, and invest his time and labor accord-. Fig. 303. ingly, taking nothing for granted and never indulging inguesswork. 1303. The Aneroid Barometer.—Fig. 304 showsan aneroid barometer, a substitute for the mercurial barom-eter, which latter is not readily portable. It consists of abox of thin corrugated copper, exhausted of air. An in-crease in the weight of the atmosphere compresses the box,and a reduction in weight admits of the box being expandedby a spring inside. This spring is connected, by a system oflevers, with a dial which indicates the pressure of theatmosphere. The face is graduated to correspond with theheights of the mercurial barometer. A thermometer is also SURVEYING. 689 attached to the face and shows the temperature when thereadings are taken.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
