from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. An optical instrument consisting of a small mounted telescope rotatable in horizontal and vertical planes, used to measure angles in surveying, meteorology, and navigation.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A surveying instrument, consisting of a small mounted telescope, used to measure horizontal and vertical angles.

from the GNU version of the Collaborative International Dictionary of English

  • n. An instrument used, especially in trigonometrical surveying, for the accurate measurement of horizontal angles, and also usually of vertical angles. It is variously constructed.

from The Century Dictionary and Cyclopedia

  • n. A surveying-instrument for measuring horizontal angles upon a graduated circle.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a surveying instrument for measuring horizontal and vertical angles, consisting of a small telescope mounted on a tripod


from The American Heritage® Dictionary of the English Language, 4th Edition

New Latin theodolitus, theodelitus.

from Wiktionary, Creative Commons Attribution/Share-Alike License

New Latin theodolitus, of unknown origin



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  • "A surveying-instrument for measuring horizontal angles upon a graduated circle. It may also be provided with a vertical circle, and If this is not very much smaller than the horizontal circle, the instrument is called an altazimuth. If it is provided with a delicate striding level and is in every way convenient for astronomical work, it is called a universal instrument. A small altazimuth with a concentric magnetic compass is called ^surveyors' transit. A theodolite in which the whole instrument, except the feet and their connections, tarns relatively to the latter, and can be clamped in different positions, is called a repeating circle. The Instrument shown in the figure follows the system of the United States Coast Survey of attaining simplicity of construction by adaptation to a single purpose—in this case to the measurement of horizontal angles only. This instrument Is low and consequently very steady. Within the upright pillar is a truncated cone of steel, and upon this and fitting to it turns the hollow brass pillar carrying the telescope and microscopes. Except for an excessively thin layer of oil, the brass movable part bears directly on the steel, and its weight tends to keep it centered. The pressure is relieved by a small plate of some elasticity fastened to the movable part over the axis and adjustable with Bcrews. It is thus made to turn, as nearly as possible, about a mathematical line. This is the conical bearing of Gambey. The base, which is as low as possible, consists of a round central part, and three arms having screw-feet with bindingscrews. A circular guardfor the circle (indistinguishable from the latter in the figure) forms a part of the base. The graduated circle is made slightly conical, so that the microscopes may be more convenient This circle, with its eight radii and interior ring, forms one solid casting,which bears upon the steel axis conically. It is held in place, in imitation of an instrument by Stackpole of New York, by the pressure of a ring above, which can readily be loosened so as to permit the circle to be turned round alone. The telescope is provided with a filar micrometer, with a view of facilitating reiterated pointings — a new principle of much value. The Instrument is leveled by means of a striding level. There are four micrometer microscopes (although some geodesists insist upon an odd number), made adjustable so that one division of the circle shall be very nearly covered by two and a halt turns of the micrometer-screw. The illumination for these microscopes 1b made through their objectives by light brought, according to the plan of Messrs. Brunner, by prisms from a point vertically over the axis, where a horizontal ground glass is hung in the daytime and a lamp with a porcelain shade at night, so that the images of the lines plowed by the graver in the polished surface of the circle shall not he displaced by oblique illumination. The clamp is attached to an arm from a ring about the brass upright, and bears upon the circular guard outside the circle proper. The tangent screw is contrived so as to eliminate dead motion. The arm carrying the clamp is balanced by another bearing a small finding microscope. Theodolites are made upon manifold models; but the one figured in preceding column is a good example of a modern firstclass instrument."


    October 26, 2014

  • Century Dictionary, Vol. VIII, Page 6273, Theodicaea to Theologue

    October 14, 2011

  • Holy cow.

    July 25, 2011

  • Whilst the layer of oil may well be exceedingly or exceptionally thin, I hope it isn't, as the definition states, excessively so.

    July 20, 2011

  • My favorite part is the conical bearing of Gamhey.

    July 20, 2011

  • The parenthetical snark about "some geodesists" is pure joy.

    July 20, 2011

  • Of all the Century's definitions, I think I love this one the most.

    July 20, 2011

  • "... a mathematical instrument generally useful, and particularly so to engineers and artillerists, in surveying and taking heights and distances."

    Falconer's New Universal Dictionary of the Marine (1816), 553

    October 12, 2008

  • That's a fine enough book review for me! :-)

    September 11, 2008

  • No, but looked it up on Amazon just now. Have you read it?

    September 11, 2008

  • I don't know much about this kind of books, but do you know "No Bone Unturned"?

    September 11, 2008

  • I liked it. It's old, though, and now I'm interested to find a similar book that's more up-to-date, so I can see if there have been any new discoveries in these particular cases since publication. For some (e.g. cholera, Robert the Bruce), probably not. But yes, it's well written and interesting.

    I suck at book reviews.

    September 11, 2008

  • Sounds like a great book, c_b. Would you recommend it?

    September 11, 2008

  • “The astonishing fact was that Mawson had taken forty-six days to drive himself on foot nearly 300 miles through the worst wilderness known to man, navigating by means of a damaged theodolite balanced on the corner of the cooker box, a compass rendered unreliable by the proximity of the South Magnetic Pole and a watch which had stopped at least two or three times. Though he kept a careful tally of his estimates for his daily marches, he had been reckoning progress by a sledge cyclometer that repeatedly jammed and broke. Yet here he was returning to base within 300 yards of his predicted line of travel.�?

    —Michael Howell and Peter Ford, The Ghost Disease, and Twelve Other Stories of Detective Work in the Medical Field, (New York: Penguin Books, 1985), 328

    September 11, 2008