Chambers
`
`Science and Technology
`Dictionary
`
`General Editor:
`
`Professor PETER M. B. WALKER, CBE, FRSE
`
`CAMBRIDGE
`
`EDINBURGH
`
`NEWYORK’ NEW ROCHELLE MELBOURNE
`
`SYDNEY
`
`FINISAR 1016
`
`FINISAR 1016
`
`

`
`Published jointly by W & R Chambers Limited
`43-45 Annandale Street, Edinburgh EH7 4A2, and
`The Press of the Syndicate of the University of Cambridge
`The Pitt Building, Trumpington Street, Cambridge CB2 1RP
`32 East 57th Street, New York, N.Y. 10022, USA
`10 Stamford Road, Oakleigh, Melbourne 3166, Australia
`
`© W & R Chambers Ltd and Cambridge University Press 1988
`First published (as Chambers '5 Technical Dictionary) 1940
`
`All rights reserved. No part of this publication may be
`reproduced, stored in a retrieval system,
`or transmitted in any form or by any means, electronic,
`mechanical, photocopying, recording or otherwise,
`without the prior permission of the copyright holders.
`
`British Library Cataloguing in Publication Data
`Chambers science and technology dictionary.——New ed.
`1. Science. Encyclopaedias—Bibliographies
`2. Technology. Encyclopaedias
`l. Walker, Peter Il. Dictionary of science and technology
`503’.2l
`
`ISBN 1—85296—l50—3
`ISBN 0—85296—l5l—1 Pbk
`
`Typeset by H. Charlesworth Ltd, Huddersfield
`
`Printed by Richard Clay Ltd, Bungay, Suffolk
`
`

`
`armour plate
`armour plate (E)-ig,), Specially heavy alloy steel plate
`forged in hydraulic presses, hardened on the surface; used
`for the protection of warships. Approximate composi-
`tion: C 0.2—0.4%. Cr l.0—3.5°/o, Ni
`l.5~3.5% and Mo
`0-0.5“/o.
`Armstrong oscillator (’Telecomm.). The original oscilla-
`tor, in which tuned circuits in the anode and grid circuits
`of a valve are coupled.
`Arndt-Eisterl reaction (Chem). Used for converting a
`carboxylic acid to a higher homologue. The acid chloride
`is added to an excess of diazomethane to form a
`diazoketone. The ketone undergoes catalytic rearrange-
`ment to the higher homologue or a derivative.
`aromatic compounds (C/1em.). Compounds related to
`benzene. Ring compounds containing conjugated double
`bonds.
`aromatic hydrogenation ( Chem. ). Hydrogenation in the
`naphthalene series, of such nature that hydrogenation
`takes place only in the unsubstituted benzene ring.
`aromatic
`properties
`(C/1em.).
`The
`characteristic
`properties of aromatic compounds, e.g. reaction with
`concentrated nitric
`acid,
`forming nitro derivatives,
`reaction with concentrated sulphuric acid,
`forming
`sulphonated derivatives. The homologues of benzene
`differ from alkanes with regard to oxidation by readily
`forming benzene carboxylic acids. There are many other
`distinguishing characteristics between aromatic hydro-
`carbons and alkanes.
`arousal (Behav.). A general psychophysiological concept
`referring to the effect of various non-specific stimulation
`or motivational factors on a number of physiological
`variables, e.g. heart rate, skin resistance. It is used to
`describe differences in responsiveness to general stimu-
`lation, usually along a continuum from drowsiness to
`alertness, for example.
`ARPA (Comp. ). Advanced Research Projects Agency.
`Supported by US government grant money and now
`renamed DARPA, Defence Advanced Research Projects
`Agency.
`ARPA Internet (Camp.). A linkage of several US networks
`including ARPANET and MILNET. It exists to facilitate
`sharing resources and collaboration by participating
`research organisations as well as to provide a testbed for
`new developments in networking.
`ARPANET (Camp) A long-distance packet switching
`US network used by research interests funded by
`ARPA.
`array (Camp). Set of storage locations referenced by a
`single identifier. Individual elements of the array are
`referenced by combining one or more subscripts with the
`identifier, e.g. NICK(20)
`is an element
`in the array
`NICK, and JOS(3,5) is an element
`in the two-dimen-
`sional array JOS.
`array (Stats. ). A set of values for a particular variate.
`array (Telecamm). Used to describe an assembly of two
`or more individual
`radiating elements, appropriately
`spaced and energized to achieve desired directional
`properties. See beam antenna.
`array bounds (Camp) Limits on the number of items in
`an array.
`array dimension (Comp) Number of subscripts neces-
`sary to identify an item in an array (e.g. CLAR(26,3) has
`dimension 2).
`array processor (Comp. ). One designed to allow any
`machine instruction to operate on a number of data
`locations simultaneously.
`In Mammals, unstriated
`arrectores pllorum (Zool.).
`muscles attached to the hair follicles, which cause the hair
`to stand on end by their contraction.
`arrested crushing (Min.Ext.). Crushing so conducted
`that the rock falling through the machine is free to drop
`clear of the zone of comminution when broken smaller
`than the exit orifice or set.
`arrested failure (Elec.Eng.). The taking of a cable off
`voltage, and examination before failure is complete. This
`is very instructive in determining the mechanism of
`breakdown.
`arrester (Elec.Eng.). See lightning arrester.
`
`51
`
`arsenide
`
`arrester gear (Aero.). (I ) A device on aircraft carriers and
`some military aerodromes, usually consisting of a
`number of individual transverse cables held by hydraulic
`shock-absorbers, which stop an aircraft when its arrester
`hook catches a cable, (2) A barrier net, usually of nylon or
`webbing attached to heavy drag weights, which stops fast
`aircraft from over—running the end of the runway in an
`emergency.
`arrester hook (Aer0.). A hook extended from an aircraft
`to engage the cable of an arrester gear, mainly on aircraft
`carriers.
`arrest points (Eng) Discontinuities on heating and
`cooling curves, due to absorption of heat during heating
`or evolution of heat during cooling, and indicating
`structural (phase) changes occurring in a metal or alloy.
`Arrhenius theory of dissociation ( Chem.). The descrip-
`tion of aqueous solutions in terms of acids, which
`dissociate to give hydrogen ions, and bases, which
`dissociate to give hydroxyl
`ions. The product of the
`reaction of an acid and a base is a salt and water. The
`dissociation of these species gives their solutions the
`property of conducting electricity.
`arrhenotoky (Z001. ). Parthenogenetic production of
`males.
`arrhythmia (Meat). Abnormal rhythm of the heart beat.
`arris (Build.). The (generally) sharp exterior edge formed
`at the intersection of two surfaces not in the same plane
`(e.g. the meeting of two sides of a stone block). See also
`external angle.
`arris edge (Glass). Small bevel, of width not exceeding
`l/16in (1.5 mm), at an angle of approximately 45” to the
`surface of the glass.
`~
`arris fillet (Build.). A small strip of wood of triangular
`cross-section packed beneath the lower courses of slates
`or tiles on a roof to throw off the water which might
`otherwise get under the flashing.
`arris gutter (Build.). A V-shaped gutter, usually made of
`wood.
`arris rail (Build.). A rail, with triangular cross-section,
`secured to posts for fences in such a manner as to show
`the arms in front.
`arris tile (Build.). Purpose-made angular tile used to cover
`the intersections at hips and ridges in slated and tiled
`roofs. See also bonnet tile.
`arris-wise (Build. ). A term used to describe the sawing of
`square timber diagonally.
`arrow (Surv.). Light steel wire pin, bent into ring at one
`end and perhaps flagged with piece of bright cloth, used
`to mark measured lengths in chain traversing.
`arsenic (Chem). Symbol As, at. no. 33, r.a.m. 74.9216,
`oxidation states 3, 5. An element which occurs free and
`combined in many minerals. An impurity of several
`commercial metals. Called grey or 'y-arsenic to distin-
`guish it from the other allotropic modifications. Mp
`814°C (36 atm.), bp 615°C (sublimes), rel.d. 5.73 at 15°C.
`Used in alloys and in the manufacture of lead shot. It is
`important as donor impurity in germanium semiconduc-
`tor devioes. The arsenic of commerce, A520,, Arsenious
`oxide, arsenic oxide. Obtained from the roasting of
`arsenical ores. It is highly poisonous, and its presence in
`foods and drinks is subject to severe restriction. Medical
`uses, once important, have much declined, but still used
`as a herbicide and rodenticide.
`arsenic acid (Chem). I-I3AsO_,. Formed by the action of
`hot dilute nitric acid upon arsenic, or by digesting arsenic
`(III) oxide with nitric acid. Arsenic acid is also formed
`when arsenic (V) oxide is dissolved in water.
`arsenical copper (Eng). Copper containing up to about
`0.6% arsenic. This element slightly increases the hardness
`and strength and raises the recrystallization temperature.
`arsenical pyrites (Min.). See arsenopyrite.
`arsenic halides (Chem). Arsenic (V) fluoride, AsF5;
`arsenic (III) fluoride, ASF3; arsenic (III) chloride, AsCl3;
`arsenic (III) bromide, AsBr3; arsenic (III) iodide, AsI3.
`arsenlde (Chem.). Arsenic unites with most metals to
`form arsenides; e.g. iron — FeAsz. Arsenides are decom-
`posed by water or dilute acids with the formation of the
`hydride arsine.