Engineering and Contracting . heaply made accounts, in large meas-ure, for the large number of those who earn a livelihoodby wielding a right-line pen. ENGINEERINGAND CONTRACTING THE GURLEY EXPLORERS ALIDADE. The plain table alidade has evoluted within a periodremembered by not very old surveyors from a blade withtwo slotted sight standards to a telescopic alidade notmuch less a precise and complex mechanism than a theod-olite. The illustrations show one of the latest and mostfinished of these recent plane table alidades. At firstglance its only pronouncedly novel feature is the elboweye piece
Engineering and Contracting . heaply made accounts, in large meas-ure, for the large number of those who earn a livelihoodby wielding a right-line pen. ENGINEERINGAND CONTRACTING THE GURLEY EXPLORERS ALIDADE. The plain table alidade has evoluted within a periodremembered by not very old surveyors from a blade withtwo slotted sight standards to a telescopic alidade notmuch less a precise and complex mechanism than a theod-olite. The illustrations show one of the latest and mostfinished of these recent plane table alidades. At firstglance its only pronouncedly novel feature is the elboweye piece, and this is its chief novelty. One of the mostfatiguing tasks in plane table surveying is that of fre-quently craning the neck to obtain horizontal sightsthrough the alidade telescope. The elbow eye piece ob-viates this awkward sighting position and increases speedand decreases labor to a noticeable degree. As the in-strument stands pictured it has a graduated blade, aBeaman stadia arc, a circular level and a trough compass. Plane Table Alldale with Elbow Eye Piece and Beaman Stadia Arc. besides the usual striding level and other fittings. Asan instrument for oil and gas land prospectors, geologistsand topographic surveying generally it is a notably com-plete instrument. While the elbow eye piece is the nov-elty, the characteristic feature is the Beaman stadia makers are W. & L. E. Gurley, Troy, N. Y. A SIMPLE METHOD OF SECURING APPROX-IMATE HORIZONTAL DISTANCES. A method of approximating horizontal distances isdescribed by G. F. Schlesinger as follows: The method, in brief, consists of turning off a horizon-tal angle of 1 9 with the transit, and then measuring thedistance between the first and last pointings at the ex-tremity of the course whose length is to be distance in hundredths of a foot, divided by 2, willbe the actual distance-in feet; depending, of course, onthe fact that the sine (or tangent) of 1° 9 is (ap-proximately). The angle of 3
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicago, bookyear19
