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mpression by touch; collision; forcible contact; force communicated. The quarrel, by that impact driven. Southey.

Driven together or close. Impacted fracture (Surg.), a fracture in which the fragments are driven into each other so as to be immovable.

fragment of bone into another so that the fragments are not movable upon each other; as, impaction of the skull or of the hip.

r measuring the force and velocity of projectiles by means of the arc through which their impact impels it.

nce of Hertzian waves; -- so called by Sir O. J. Lodge in 1894 on the assumption that the impact of the electic waves caused the loosely connected parts to cohere, or weld together, a condition easily destroyed by tapping. A common form of coherer as used in wireless telegraphy consists of a tube containing filings (us…

a mass of steam in the end of the cylinder of a steam engine to receive the impact of the piston;

in addition to its forward motion a spinning motion, that influences its direction after impact on another ball or the cushion. [U.S.]

In California, a water wheel with radial buckets, driven by the impact of a jet.

An instrument to measure the velocity of a liquid current by the force of its impact.

a percussion drill to the rod or rope which works it, so that the drill is driven down by impact and is jerked loose when jammed.

sists of the expelled alpha particles. The heat effect mentioned above is ascribed to the impacts of these particles. Radium, in turn, is believed to be formed indirectly by an immeasurably slow disintegration of uranium.

uivering or shaking which is the effect of a blow, collision, or violent impulse; a blow, impact, or collision; a concussion; a sudden violent impulse or onset. These strong, unshaken mounds resist the shocks Of tides and seas tempestuous. Blackmore. He stood the shock of a whole host of foes. Addison.…

rcumference of which spiral vanes or floats, placed radially, are attached, turned by the impact of one or more streams of water, conducted so as to strike against the floats in the direction of a tangent to the cylinder.