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. . . . MIL-HDBK-850
en~w###rf 600 myabytes) of digital
mfmxCpc pits which canba
read try a fsaer beam. Rasmrdad data cannot
be erased or altered. CDROfd mrrpiies with
the Yellow Book standard.
compacted date-f)igital data that have
been reduced In votuma using a bssless
technique. Lossless means no information is
bat arxt afl of the original data will be reaidenf
when urpadmrt. ~hess techniques ara
designed to remove radundanciaa and employ
apadal techniques.]
COSSIpSrStWO covor+JCS) CoveraOe of the
earns area or ob@f taken at diierent times 10
ahow any cha~as In detail. See also beak
cover; cover; coverage.
comparator baae-See field comparator.
comparator—l. An Inefrumam or apparatus
for maasurtrrg a dimension in terms of a
standard. 2. A precision optical instrument used
to determine the rectangular coordinates of a
point with respect to another poinl on any plane
surface, such as a photographic plate, 3.
(surveying) An instrument for cornpsrino
standards of lar@h: for suMtiidhg such
standards: or Ior determining a standard length
ot measuring devices (bar, tape, etc.). See also
tleld comparator; monocomparator;
eteroocompsrator; Valsala comparator;
vertical comparator.
compass amplltude-Ampfitude relative to
compaas aast or west. See also ampllkrde.
compaas bearing—l. (navigation) Bearing
relatffe to compass north. See also mognetlc
bearing, definition 1.2. (surveying) See
magnetic baarlng, definition 2.
compass Index error—The Instrument error
in the magnetic beadrrg given by readings of tha
needle.
compass norsfs-(JCS) Tha uncorrected
direction indicated by the norfh-sseking end of a
compass needle. See also magnetic north.
[Compasa north and magnetic north differ
in that the former may be determined by other
influences than the Earih’e magnetic Iiald.]
compass roaa+JCS) A graduated circle,
usually marked in degrees lndicatin~ directions
and primed or Inscribed on an appropriate
medium.
compass rula-A melhod ot balancing a
traverse survey. Corrections cormmrdii to
the closing errors in latitude and departure are
d@ribulad according to the proptrrfbn (lar@h of
line to lotal length of travarse). The compass
rule is uaad when If & assumed that the cbshrg
errors are as much due to errors in obsarvad
anglaa aa to errors in measured diatancaa.
compsaa surwsy-A traverse survey whbh
reties on the magnatk needle for onenfhg the
sequence as a whole or tor determining the
baarings ot the fines indviclually.
compass—An Ins;rumam for Irrdiialing a
horisomal reieranoe dlrectbn relafiia IO the
Eanh. see alao aperlodlc compass; aatro
compaaa; Brunton compass;
clrcumfsremor; dscllnatolrsr;
declkrometer; Earth Inductor compasa;
gyro compaae; gyromsgnetlc compass;
tensatlc compsss; Ilquid hand compase;
magnetic compass; peap sight
compsaa; prismatic compass.
compensated gsold—A surface derived
from the gaoid by apptiiaiion of computed
values of tha deflection of the vertical which
depend upon the topographic and isos!atic
compensation. Also called cogeold.
compensating backslgfsts ●nd
toraslghls—When backaiglst and foresight
dislancea are aquai al a given poskion of a level
insfnsment, the effects ot curvature, refraction,
arsf lack of adjustment of line of sight (if bubble
is Ieveied when taking a rod reading) are
compensated for. Backsight and foresighl
distances are ammonly comrolled by the use of
pacing or atadia.
compenaatksg base-line measuring
aPPa ratus—A base apparatus having a length
elemant composed of two metala haviW
different coefficients of thermsl expanaion. so
amanged and connected fhat fhe differamial
expansion of tfs camponems will maintain a
COnStant length of the elamem under all
temperature conditions of use.
compansatlng error—An error that tends to
ottsef a companion error and thus obscsxe or
reduce the affecl of each.
compansatkrg lene-(photogrammef~) A
lens introduced info an optical sysfem to wrrecf
for radial dislortbn.
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