Columbia Encyclopedia

(Encyclopedia) hail, precipitation in the form of pellets composed of ice or of ice and snow, occurring at any time of the year, usually during the passage of a cold front or during a thunderstorm. Small hailstones ...

(Encyclopedia) pendulum, a mass, called a bob, suspended from a fixed point so that it can swing in an arc determined by its momentum and the force of gravity. The length of a pendulum is the distance from the point...

(Encyclopedia) atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a...

(Encyclopedia) sea level, the level of the sea, which serves as the datum used for measurement of land elevations and ocean depths. Theoretically, one would expect sea level to be a fixed and permanent horizontal su...

(Encyclopedia)  CE5 A pendulum clock: Weight-driven clock mechanism clock, instrument for measuring and indicating time. Predecessors of the clock were the sundial, the hourglass, and the clepsydra. See also watc...

(Encyclopedia) Chamberlin, Guy (Berlin Guy “Champ” Chamberlin), 1894–1967, American football coach and player, b. Blue Springs, Neb., grad. Univ. of Nebraska, 1916. Chamberlin was one of the greatest ends of h...

(Encyclopedia) obscenity, in law, anything that tends to corrupt public morals by its indecency. The moral concepts that the term connotes vary from time to time and from place to place. In the United States, the wo...

(Encyclopedia) iron lung, device used to maintain artificial respiration over an extended period of time. Before the successful vaccination program against poliomyelitis, it was used mostly in treatment of that dise...

(Encyclopedia) megatherium mĕgəthērˈēəm [key] [Gr.,=large beast], extinct ground sloth, of the genus Megatherium, that was widely distributed in North and South America in the Pleistocene epoch. Fossil evidenc...

(Encyclopedia) Djokovic, Novak, 1987–, Serbian tennis player, b. Belgrade. He began winning European championships at age 14, and played in his first Grand Slam tournament, the Australian Open, in 2005. He won the...