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A core drill with hardened steel shot pellets that revolve under the rim of the rotating tube; employed in rotary drilling in very hard ground.

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A torch in which temperatures as high as 50,000 C are achieved by injecting a plasma gas tangentially into an electric arc formed between electrodes in a chamber; the resulting vortex of hot gases emerges at very high speed through a hole in the negative electrode, to form a jet for welding, spraying of molten metal, and cutting of hard rock or hard metals.


1. A hard floor of concrete, brick, tiles, or other material. 2. A paved surface.


A log that employs an electrical resistivity element in the form of four symmetrically arranged current electrodes to give accurate readings in borehole surveying of hard formations.


A bit into which inset cutting points of various preshaped pieces of hard metal (usually a sintered tungsten carbidecobalt powder alloy) are brazed or hand-peened into slots or holes cut or drilled into a blank bit. Also known as slug bit.


A machine that blends or emulsifies a substance by forcing it through fine openings against a hard surface.


A two-flute twist drill with a helix angle of 3540 ; used for drilling deep holes in metals, such as aluminum, copper, hard brass, and soft steel. Also known as fastspiral drill.


Comes about when hard surface asperities or hard particles that have embedded themselves into a soft surface and plough grooves into the opposing harder surface, e.g., a journal.


A portion of a beach especially prepared with a hard surface extending into the water, employed for the purpose of loading or unloading directly into landing ships or landing craft


A type of precipitation consisting of transparent or translucent pellets of ice, 5 millimeters or less in diameter. The pellets may be spherical, irregular, or (rarely) conical in shape. They usually bounce when hitting hard ground, and make a sound upon impact. Ice pellets includes two basically different types of precipitation, those which are known in the United States as SLEET and SMALL HAIL. Sleet is generally transparent, globular, solid grains of ice which have formed from the freezing of raindrops or the refreezing o


A hard and long-lasting dry biscuit, used as food on long journeys. Also called ship's biscuit.

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