Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . s fromthe traverse, their elevations may be determined by thevertical angle read to them with the telescopic alidade orthe vertical-angle sight-alidade (Arts, 59 and 62); the angle ENGINEERS TRANSIT. 203 read with the distance which can be measured from the plane-table furnishing data from which to compute, or obtain fromtables, differences of elevation (Art. 163). 85. EnginecFs Transit.—This is the instrument com-monly employed by surveyors for the angula
Topographic surveying; including geographic, exploratory, and military mapping, with hints on camping, emergency surgery, and photography . s fromthe traverse, their elevations may be determined by thevertical angle read to them with the telescopic alidade orthe vertical-angle sight-alidade (Arts, 59 and 62); the angle ENGINEERS TRANSIT. 203 read with the distance which can be measured from the plane-table furnishing data from which to compute, or obtain fromtables, differences of elevation (Art. 163). 85. EnginecFs Transit.—This is the instrument com-monly employed by surveyors for the angular measurementof directions. It consists of a telescope supported in axes,called wyes, in which it can revolve in a vertical plane whilethe whole revolves in a horizontal plane, the amount of bothmovements being measured on graduated circles read withverniers. There are suitable attachments for clamping thetelescope and the horizontal circle, and for moving themslowly by means of an apparatus called a tangent the whole may be revolved about a second horizontalaxis (Fig. 65). The transit is an instrument but little used. Fig. 65.—Section of Engineers Transit. by topographic surveyors, and is so commonly employed inordinary surveying and described in text-books and cataloguesthat its description will not be elaborated here. There arevarious forms, sizes, and patterns of transits, differing with theideas of the makers and the work for which they are intended,and the catalogues furnished by the makers thoroughlydescribe the modes of adjusting and using these instruments. 204 TRAVERSE INSTRUMENTS AND METHODS. The chief points to be remembered in selecting a transitare the work for which it is to be used. If the best work isnot to be executed, and portabihty is an object, a lightmountain transit with circles reading to but one minute willbe sufficiently accurate. If the highest grade of work is tobe performed, large, heavy instruments having circles read-ing to twent
Size: 1956px × 1278px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookdecade1900, bookpublishernewyorkjwiley
