A to Accelerating jet

Abscissa
a. Abbreviation for ampere, acceleration. A. The symbol for area: ampere ab­
solute temperature: relative atomic mass atomic weight) magentic vec­tor potential.
A. The symbol for Angstorm (I A =
10-10 m)
Ab. A prefix, which when placed befoAre the name of a practical electrical unit represents the corre­sponding electrical unit in the electro magentic system.
A-battery (Elec.). The source of supply for filament power in a bat­tery-operated radio set.
Abacus (Arch.). The upper part of the capital of a column, either square or curved. (Math.) A calcu­lating table with sliding balls on wires or sticks.
Abbe number. Refers to the reciprocal of the dispersive power of a substance.
Abbe refractometer. An instrument for measuring the referactive in­dex of liquids.
Aberration. A disturbance of the rays of a pencil of light such that they can no longer be brought to a sharp focus or form a clear image.
Ablation (Aero.fp.). The melting of special heat-dissipating materials on the heat shield of a spacecraft during re-entry into the atmos­phere.
Abnormal reflection. Reflection of the radio waves from the iono­sphere at frequenCies that are higher than the critical frequency of the layer.
Abrasion. The process of reducing material by grinding instead of cutting with tools.
Abrasive. Grinding material such as sandstone, emery, carborundum, etc. The I'!atural abrasives include the diamond, emery, corundum, sand, crushed garnet and quartz. tripoli, and pumice. The artifical abrasives are in general either sili­con carbide or aluminium oxide, and are marketed under many trade names.
Abrasive paper. Paper or cloth upon which flint, garnet, emery. or corundum has been fastened with glue or some other adhesive.
Abscissa (Math.). The length of an axis at right angles to the axis of ordinates.
Absolute ceiling. (Aero.) The max.i­mum height in a standard atmos­phere at which a given airplane under specified operating condi­tions can maintain horizontal flight.
Absolute motion. (phys.) Records successive changes of position with respect to a point in space which is regarded as ideally fixed.
Absolute pitch. The exact pitch of a tone in terms of vibrations per second.
Absolute pressure. Pressure measured with respect to zero; pressure in units of force per unit of area.
Absolute scale. A temperature scale in which zero corresponds to abso­lute zero.
Absolute temperature. Temperature measured on an absolute scale. Absolute value. The magnitude of quantity irrespective of its sign. Absolute zero (Pltys.). -273°ccntrigrade; -459.2° Fahrenheit.
Absorbent cotton. (Textile) Cotton with fatty and waxy maller removed to increase its absorbency.
Absorptance. The ratio of the amount of radiation absorbed by a surface to the amount of radia­tion incident upon it.
Absorption. The reduction of en­ergy in the form of electromag­netic radiation by a medium or reflecting surface.
Absorption coefficient. A measure of the rate 0f d~crease in the in­tensity of electromagnetic radia­tion, such as light, as it passes through a given substance.
Absorption dynamometer. (Elec.) A form of dynamometer in which the measured energy is absorbed by frictional resistance and is not transmitted to other machines to perform useful work.
Abstract design. Design based on
geometric. lines and shapes.
Abutment. (Arch. and Ellgin.) The support of an arch, beam, or bridge, which receives thrust; dis­tinguished from pier.
a.c. (Elec.). Alternating current. Acacine gum. Same as gum arabic.
Acanthus. (Arch. and Fum.) A
Greek conventional leaf ornament used as a decorative feature of carved furniture, and a character­istic of the Corinthian capital.
Accelerated motion. (Mech.) Motion in which velocity is not constant. The term is used in
reference to both increased and decreased velocity, although, when decreased, it is known as "negative accelerated motion."
Accelerating jet. (Auto. Mech.) The
carburetor jet through which the
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