A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &c. Illustrated by four hundred engravings, and a magnetic chart (1875)
Gillespie, W. M. (William Mitchell), 1816-1868 · New York, D. Appleton · leaf 229
s. Thesupports, or standards, of the telesco^jejust described are attached to the upper, or index-carrj-ing circle.*This, as has been stated, can turn freely on the lower or graduatedcircle, by means cf its conical axis moving in the hollow conicalaxis of the latter circle. This upper circle… … which is an arrow-head or other mark on its edge, or the zero-point ofa Vernier scale. There are usually two of these, situated exactlyopposite to each other, or at the extremities of a diameter of theupper circle, so that the readings on the graduated circle pointed outby them differ, if both are…
Surveying
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-318-210.webp)
