Part 253

Di*am"e*ter (?), n. [F. diamètre, L. diametros, fr. Gr. &?;; dia` through + &?; measure. See Meter.] 1. (Geom.) (a) Any right line passing through the center of a figure or body, as a circle, conic section, sphere, cube, etc., and terminated by the opposite boundaries; a straight line which bisects a system of parallel chords drawn in a curve. (b) A diametral plane.

2. The length of a straight line through the center of an object from side to side; width; thickness; as, the diameter of a tree or rock.

In an elongated object the diameter is usually taken at right angles to the longer axis.

3. (Arch.) The distance through the lower part of the shaft of a column, used as a standard measure for all parts of the order. See Module.

Conjugate diameters. See under Conjugate.

Di*am"e*tral (?), a. [Gr. F. diamétral.] Pertaining to a diameter; diametrical.

Diametral curve, Diametral surface (Geom.), any line or surface which bisects a system of parallel chords drawn in a curve or surface. -- Diametral planes (Crystal.), planes in which two of the axes lie.

Di*am"e*tral, n. A diameter. [Obs.] Sir T. Browne.

Di*am"e*tral*ly, adv. Diametrically.

{ Di*am"e*tric (?), Di*am"e*tric*al (?), } a. 1. Of or pertaining to a diameter.

2. As remote as possible, as if at the opposite end of a diameter; directly adverse.

Di*am"e*tric*al*ly, adv. In a diametrical manner; directly; as, diametrically opposite.

Whose principles were diametrically opposed to his.

Macaulay.

Di*am"ide (?; 104), n. [Pref. di- + amide.] (Chem.) Any compound containing two amido groups united with one or more acid or negative radicals, -- as distinguished from a diamine. Cf. Amido acid, under Amido, and Acid amide, under Amide.

Di*am"i*do- (&?;), a. (Chem.) A prefix or combining form of Diamine. [Also used adjectively.]

Di*am"ine (?; 104), n. [Pref. di- + amine.] (Chem.) A compound containing two amido groups united with one or more basic or positive radicals, -- as contrasted with a diamide.

In chemical nomenclature, if any amine or diamine is named by prefixing the nitrogen group, the name of the latter takes the form of amido, diamido, etc., thus ethylene diamine, C2H4.(NH2)2, is also called diamido-ethylene.

Di"a*mond (?; 277), n. [OE. diamaund, diamaunt, F. diamant, corrupted, fr. L. adamas, the hardest iron, steel, diamond, Gr. &?;. Perh. the corruption is due to the influence of Gr. &?; transparent. See Adamant, Tame.] 1. A precious stone or gem excelling in brilliancy and beautiful play of prismatic colors, and remarkable for extreme hardness.

The diamond is native carbon in isometric crystals, often octahedrons with rounded edges. It is usually colorless, but some are yellow, green, blue, and even black. It is the hardest substance known. The diamond as found in nature (called a rough diamond) is cut, for use in jewelry, into various forms with many reflecting faces, or facets, by which its brilliancy is much increased. See Brilliant, Rose. Diamonds are said to be of the first water when very transparent, and of the second or third water as the transparency decreases.

2. A geometrical figure, consisting of four equal straight lines, and having two of the interior angles acute and two obtuse; a rhombus; a lozenge.

3. One of a suit of playing cards, stamped with the figure of a diamond.

4. (Arch.) A pointed projection, like a four-sided pyramid, used for ornament in lines or groups.

5. (Baseball) The infield; the square space, 90 feet on a side, having the bases at its angles.

6. (Print.) The smallest kind of type in English printing, except that called brilliant, which is seldom seen.

This line is printed in the type called Diamond.

Black diamond, coal; (Min.) See Carbonado. -- Bristol diamond. See Bristol stone, under Bristol. -- Diamond beetle (Zoöl.), a large South American weevil (Entimus imperialis), remarkable for its splendid luster and colors, due to minute brilliant scales. -- Diamond bird (Zoöl.), a small Australian bird (Pardalotus punctatus, family Ampelidæ.). It is black, with white spots. -- Diamond drill (Engin.), a rod or tube the end of which is set with black diamonds; -- used for perforating hard substances, esp. for boring in rock. -- Diamond finch (Zoöl.), a small Australian sparrow, often kept in a cage. Its sides are black, with conspicuous white spots, and the rump is bright carmine. -- Diamond groove (Iron Working), a groove of V-section in a roll. -- Diamond mortar (Chem.), a small steel mortar used for pulverizing hard substances. - - Diamond-point tool, a cutting tool whose point is diamond-shaped. -- Diamond snake (Zoöl.), a harmless snake of Australia (Morelia spilotes); the carpet snake. -- Glazier's diamond, a small diamond set in a glazier's tool, for cutting glass.

Di"a*mond (?; 277), a. Resembling a diamond; made of, or abounding in, diamonds; as, a diamond chain; a diamond field.