A Treatise of Mathematical Instruments, including most of the instruments employed in Drawing; for assisting the vision; in Surveying and Levelling, in practical Astronomy and for measuring the Angles of Crystals1864 |
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Common terms and phrases
accuracy adjustment ÆSCHYLUS altitude AMEN CORNER arc of excess arrows astronomical attached azimuth beam compasses bisected brass bubble called chain chords clamp coincide columns compasses construction correct cross wires described diaphragm difference Ditto ditto divided division drawing edge equal extent will reach eye-piece feet figure fixed focal length goniometer graduated Gunter's chain half horizon glass inches index glass instru instrument intersection latitude lens lenses light limb line of collimation line of sines logarithmic marked means measured ment meridian method microscope moved object object-glass observed parallax parallel plate screws pencil perpendicular plane position prism protractor radius rays reading reflected image reflector refracting telescopes refraction represent right angles right ascension round scale sextant side sixth column spirit level square staff station strument survey tangent telescope theodolite transit transverse distance Troughton's tube turning vernier plate vernier scale vertical axis vertical circle zero