Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . e stations. This instrument is most used in rough traversing andin sketching topography where there are no roads and it isimposssible to carry heavy instruments, because the traverse-man moves either on foot or horseback; its use is limited indistance, but for work on a scale of one or two miles to theinch it gives comparatively accurate results for distances notexceeding one or two miles and for elevations less than 8or lO degrees. In sketching in details
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . e stations. This instrument is most used in rough traversing andin sketching topography where there are no roads and it isimposssible to carry heavy instruments, because the traverse-man moves either on foot or horseback; its use is limited indistance, but for work on a scale of one or two miles to theinch it gives comparatively accurate results for distances notexceeding one or two miles and for elevations less than 8or lO degrees. In sketching in details of topographyalong a road traveled on foot or by conveyance it is alsoconvenient in determining the elevations of unimportantpoints near by, as it is much more rapidly used than the tele-scopic alidade. FOLDING EXPLORATORY PLANE-TABLE. 163 63. Folding Exploratory Plane-table.—This consists ofa folding split-leg tripod similar to those made for supportingphotographic cameras, but a little more substantial. Thethree legs are carried in a canvas case 24 inches in length and3 by 4 inches in cross-section. The tripod head consists of a. Fig. 54.—Folding Exploratory Plane-table and Small Theodolite. triangular block of wood 7 inches on each side by i inchthick, with metal pegs on the under side into which the split^legs of the tripod are sprung, and carrying a centre binding-screw for clamping the plane-table movement. This latterconsists of three small bronze arms, in general shape likethose of a theodolite or transit, supported by three leveling- 164 PLANE-TABLES AND ALIDADES. screws and having a clamp and tangent screw. (Fig. 54.)The top of the movement is a screw 3^ inches in diameter, towhich are fastened the cross-braces which support the are two strips of wood, 24 inches in length by 3 inchesin width and i inch in thickness, and to the four ends ofthese cross-arms are screwed the outer slats of the foldingboard. T\\Q plane-table board consists of 24 wooden sla
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License: Licensed
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Keywords: ., book, bookcentury1900, bookdecade1900, bookpublishernewyorkjwiley
