Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Brown, Green, Longmans, and Roberts · leaf 200
164 OUTLINES OF ASTRONOMY. For this purpose, therefore, the zenith sector (an instrument capable of great precision) is most commonly used to observe stars passing the meridian near, the zenith, whose declinations have become known by previous long series of observations at fixed observatories, and… … D with great success, which consists in the use of an instrument similar in every respect to the transit instrument, but having the plane of motion of the telescope not coincident with the meridian, but with the prime vertical, so that its axis of rotation prolonged passes through the north and…
Astronomy
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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-343-234.webp)
