1. (Naut.) A forestaff.
2. (Physics) An instrument designed for measuring the mechanical effect of radiant energy.
It consists of a number of light disks, blackened on one side, placed at the ends of extended arms, supported
on a pivot in an exhausted glass vessel. When exposed to rays of light or heat, the arms rotate.
(Ra`di*o*mi*crom"e*ter) (- o*mi*krom"e*ter), n. [Radio- + micrometer.] (Physics) A
very sensitive modification or application of the thermopile, used for indicating minute changes of radiant
heat, or temperature.
(Ra"di*o*phone) n. [Radio- + Gr. fwnh` sound.] (Physics) An apparatus for the production
of sound by the action of luminous or thermal rays. It is essentially the same as the photophone.
(Ra`di*oph"o*ny) n. (Physics) The art or practice of using the radiophone.
(Ra"di*ous) a. [L. radiosus.]
1. Consisting of rays, as light. [R.] Berkeley.
2. Radiating; radiant. [Obs.] G. Fletcher.
Radish fly (Zoöl.), a small two- winged fly (Anthomyia raphani) whose larvæ burrow in radishes. It resembles
the onion fly. Rat-tailed radish (Bot.), an herb (Raphanus caudatus) having a long, slender pod,
which is sometimes eaten. Wild radish (Bot.), the jointed charlock.
(Rad"ish) n. [F. radis; cf. It. radice, Pr. raditz; all fr. L. radix, -icis, a root, an edible root, especially
a radish, akin to E. wort. See Wort, and cf. Eradicate, Race a root, Radix.] (Bot.) The pungent
fleshy root of a well-known cruciferous plant (Raphanus sativus); also, the whole plant.
(Ra"di*us) n.; pl. L. Radii (- i); E. Radiuses [L., a staff, rod, spoke of a wheel, radius, ray. See
Ray a divergent line.]
1. (Geom.) A right line drawn or extending from the center of a circle to the periphery; the semidiameter
of a circle or sphere.
2. (Anat.) The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb.
See Illust. of Artiodactyla.
The radius is on the same side of the limb as the thumb, or pollex, and in man it is so articulated that its
lower end is capable of partial rotation about the ulna.
3. (Bot.) A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See
4. pl. (Zoöl.) (a) The barbs of a perfect feather. (b) Radiating organs, or color-markings, of the radiates.
5. The movable limb of a sextant or other angular instrument. Knight.
Radius bar (Mach.), a bar pivoted at one end, about which it swings, and having its other end attached
to a piece which it causes to move in a circular arc. Radius of curvature. See under Curvature.