Parks and park engineering . THE TOPOGRAPHICAL SURVEY 31 All angles should be doubled and checked by the needle,and all distances should be checked by stadia. Sideshots are obtained by angles and stadia distances. Thismethod of survey is not as accurate as the gridiron method,but the latter in its simplest form is not adapted to park- V 1 L. 2+R 7 + 00 0 + 00 IB jjh + Modified Gridiron System of Surueg for Parkways* FIG. 8. way work. A modified girdiron system, however, maybe used when the base-line instead of being one straightline is the broken line of traverse. General Remark. In making
Parks and park engineering . THE TOPOGRAPHICAL SURVEY 31 All angles should be doubled and checked by the needle,and all distances should be checked by stadia. Sideshots are obtained by angles and stadia distances. Thismethod of survey is not as accurate as the gridiron method,but the latter in its simplest form is not adapted to park- V 1 L. 2+R 7 + 00 0 + 00 IB jjh + Modified Gridiron System of Surueg for Parkways* FIG. 8. way work. A modified girdiron system, however, maybe used when the base-line instead of being one straightline is the broken line of traverse. General Remark. In making topographical surveysit is sometimes advantageous to sketch in field. Work ofthis kind is usually much more accurate, especially when 32 LANDS AND SURVEYS the map must be drawn in minute detail. It is advanta-geous where there are terraces, trees, etc. Mistakes inplotting are thus avoided, since the features are withinsight of the draftsman. A plane table is a useful instru-ment for this kind of work; but it can be done with atransit with vertical circle, the draftsman using a lighttable 2 feet square mounted on a light tripod. THE HYDROGRAPmCAL SURVEY Ponds and Lakes. The topography of the beds of pondsand lakes is obtained by the gridiron method of depths may be had in shallow ponds by use of a rodlowered from a boat, the r
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishere, booksubjectparks
