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An instrument designed for measuring the mechanical effect of radiant energy.

The use of the radiometer, or the measurement of radiation. -- Ra`di*o*met"ric (#), a.

tive modification or application of the thermopile, used for indicating minute changes of radiant heat, or temperature.

A radiotelegraphic station serving solely for determining the position of ships. The radius of operation of such stations was restricted by the International Radiotelegraphic Convention (1912) to 30 nautical miles.

An apparatus for the production of sound by the action of luminous or thermal rays. It is essentially the same as the photophone.

The art or practice of using the radiophone.

See Projector, above.

Direct observation of objects opaque to light by means of some other form of radiant energy, as the Röntgen rays. -- Ra`di*o*scop"ic (#), *scop"ic*al (#), a.

A message transmitted by radiotelegraph.

A wireless telegraph.

Of or pertaining to radiotelegraphy; employing, or used or employed in, radiotelegraphy.

Telegraphy using the radiant energy of electrical (Hertzian) waves; wireless telegraphy; -- the term adopted for use by the Radiotelegraphic Convention of 1912.

A wireless telephone. -- Ra`di*o*te*leph"o*ny (#), n.

Treatment of disease by means of Röntgen rays or other forms of radioactivity.

A radioactive substance apparently formed as a product from thorium.

Consisting of rays, and light. [R.] Berkeley.

fleshy root of a well-known cruciferous plant (Paphanus sativus); also, the whole plant. 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 ea…

An intensely radioactive metallic element found (combined) in minute quantities in pitchblende, and various other uranium minerals. Symbol, Ra; atomic weight, 226.4. Radium was discovered by M. and Mme. Curie, of Paris, who in 1902 separated compounds of it by a tedious process from pitchblende. Its compounds color fla…

A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.

A straight line (or the length of such line) connecting any point, as of a curve, with a fixed point, or pole, round which the straight line turns, and to which it serves to refer the successive points of a curve, in a system of polar coördinates. See Coördinate, n.