A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects (1852)
Robinson, Horatio N[elson], 1806-1867. [from old catalog] · Cincinnati, J. Ernst · leaf 119
s attached to the lower plate, the horizontalposition is attained with a sufficient degree of accuracy. The figure beforeus, represents theessential parts of acircumferentor. JVSis considered as theprimative or meri-dian line, and AB isthe index bar, whichturns horizontally onthe common center.… … TO SURVEY WITHOUT A COMPASS. 115 the plane AB, and the diameter of that circle a telescope, then wehave all the essentials of a theodolite. To most theodolites, a magnetic needle is attached, but the mag-netic needle is, properly speaking, no part of the instrument. To show the manner of finding…
Surveying · Navigation
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