Found 1 items, similar to Ring micrometer.
English → English (gcide) Definition: Ring micrometer Micrometer \Mi*crom"e*ter\, n. [Micro- + -meter: cf. F. microm[`e]tre.] An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given directly is that of the image of the object formed at the focus of the object glass. [1913 Webster] Circular micrometer, or Ring micrometer, a metallic ring fixed in the focus of the object glass of a telescope, and used to determine differences of right ascension and declination between stars by observations of the times at which the stars cross the inner or outer periphery of the ring. Double image micrometer, a micrometer in which two images of an object are formed in the field, usually by the two halves of a bisected lens which are movable along their line of section by a screw, and distances are determined by the number of screw revolutions necessary to bring the points to be measured into optical coincidence. When the two images are formed by a bisected object glass, it is called a divided-object-glass micrometer, and when the instrument is large and equatorially mounted, it is known as a heliometer. Double refraction micrometer, a species of double image micrometer, in which the two images are formed by the double refraction of rock crystal. Filar micrometer, or Bifilar micrometer. See under Bifilar. Micrometer caliper or Micrometer gauge (Mech.), a caliper or gauge with a micrometer screw, for measuring dimensions with great accuracy. Micrometer head, the head of a micrometer screw. Micrometer microscope, a compound microscope combined with a filar micrometer, used chiefly for reading and subdividing the divisions of large astronomical and geodetical instruments. Micrometer screw, a screw with a graduated head used in some forms of micrometers; turning the head one full revolution advances the position of the tip of the screw only by a little. Position micrometer. See under Position. Scale micrometer, or Linear micrometer, a minute and very delicately graduated scale of equal parts used in the field of a telescope or microscope, for measuring distances by direct comparison. [1913 Webster] Ring \Ring\, n. [AS. hring, hrinc; akin to Fries. hring, D. & G. ring, OHG. ring, hring, Icel. hringr, DAn. & SW. ring; cf. Russ. krug'. Cf. Harangue, Rank a row,Rink.] A circle, or a circular line, or anything in the form of a circular line or hoop. [1913 Webster] 2. Specifically, a circular ornament of gold or other precious material worn on the finger, or attached to the ear, the nose, or some other part of the person; as, a wedding ring. [1913 Webster] Upon his thumb he had of gold a ring. --Chaucer. [1913 Webster] The dearest ring in Venice will I give you. --Shak. [1913 Webster] 3. A circular area in which races are or run or other sports are performed; an arena. [1913 Webster] Place me, O, place me in the dusty ring, Where youthful charioteers contend for glory. --E. Smith. [1913 Webster] 4. An inclosed space in which pugilists fight; hence, figuratively, prize fighting. “The road was an institution, the ring was an institution.” --Thackeray. [1913 Webster] 5. A circular group of persons. [1913 Webster] And hears the Muses in a ring Aye round about Jove's alter sing. --Milton. [1913 Webster] 6. (Geom.) (a) The plane figure included between the circumferences of two concentric circles. (b) The solid generated by the revolution of a circle, or other figure, about an exterior straight line (as an axis) lying in the same plane as the circle or other figure. [1913 Webster] 7. (Astron. & Navigation) An instrument, formerly used for taking the sun's altitude, consisting of a brass ring suspended by a swivel, with a hole at one side through which a solar ray entering indicated the altitude on the graduated inner surface opposite. [1913 Webster] 8. (Bot.) An elastic band partly or wholly encircling the spore cases of ferns. See Illust. of Sporangium. [1913 Webster] 9. A clique; an exclusive combination of persons for a selfish purpose, as to control the market, distribute offices, obtain contracts, etc. [1913 Webster] The ruling ring at Constantinople. --E. A. Freeman. [1913 Webster] Ring armor, armor composed of rings of metal. See Ring mail , below, and Chain mail, under Chain. Ring blackbird (Zo["o]l.), the ring ousel. Ring canal (Zo["o]l.), the circular water tube which surrounds the esophagus of echinoderms. Ring dotterel, or Ringed dotterel. (Zo["o]l.) See Dotterel, and Illust. of Pressiroster. Ring dropper, a sharper who pretends to have found a ring (dropped by himself), and tries to induce another to buy it as valuable, it being worthless. Ring fence. See under Fence. Ring finger, the third finger of the left hand, or the next the little finger, on which the ring is placed in marriage. Ring formula (Chem.), a graphic formula in the shape of a closed ring, as in the case of benzene, pyridine, etc. See Illust. under Benzene. Ring mail, a kind of mail made of small steel rings sewed upon a garment of leather or of cloth. Ring micrometer. (Astron.) See Circular micrometer, under Micrometer. Saturn's rings. See Saturn. Ring ousel. (Zo["o]l.) See Ousel. Ring parrot (Zo["o]l.), any one of several species of Old World parrakeets having a red ring around the neck, especially Pal[ae]ornis torquatus, common in India, and Pal[ae]ornis Alexandri of Java. Ring plover. (Zo["o]l.) (a) The ringed dotterel. (b) Any one of several small American plovers having a dark ring around the neck, as the semipalmated plover ([AE]gialitis semipalmata). Ring snake (Zo["o]l.), a small harmless American snake (Diadophis punctatus) having a white ring around the neck. The back is ash-colored, or sage green, the belly of an orange red. Ring stopper. (Naut.) See under Stopper. Ring thrush (Zo["o]l.), the ring ousel. The prize ring, the ring in which prize fighters contend; prize fighters, collectively. The ring. (a) The body of sporting men who bet on horse races. [Eng.] (b) The prize ring. [1913 Webster]