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sphere fmm a polm on the Earth. 3. (surveying)
See beerlng of Ilne. See ako aatronomlc
basrlng; back bearing; compass
bearing; computed bearing; curve of
equsl baarlrvg; ●tactronlc bearing; false
bearing; gram. clrcSe baarlng; grid
bearing; Lambwfl baarlng; magnatlc
bearing; polar bearing; rhumb baarlnry:
trssa bearing.
Boll gravity mater-A single-axis, pendulous
torte rebalance accelerometer mounmd on a
stabilized ptetfonn and Interfaced to a cfynamfc
d~ket friar tor measuring gravity aboard a
awvey platform.
trench mark (BM)-A marked vertical cxmtrol
point whkh has been located on a relatively
permanent rnaterfal object, natural or artificial,
and whose etevatbn above or below an
adopted datum has been established. It Is
usually monumenttxf 10 include bench mark
name or number, frequently ffs elevation, and
the name et the respsnslble agency. Since
elevations are computed at a later time, lhey
era aekfom addsd to nawer control bench
marks. A EM (aside horn a vertical anole bench
ma~) seldom ‘kas a surveyed iatltude ~r
lorrgiiude. See also flrat.”order bench mertr;
pctlon bench mark; permanent bench
mark; primary banch mark; second.
order borsch mark; temporary bench
merk; lldef bench mark; verflcal-arrgle
bench mark.
Bessel ●pherold (elllpaold)—A reference
ellipsoid having the following approximate
dimensions: eemimajor axis-6,377,397.2
metem; semiminor exis-6,356,078.9 meters:
and the flattening or elfipticity-1 /239.15.
Bassaf’a mathod—See Wlangle.ol-arror
mathod.
Baaeellan star numbers-Conslants used
in the reductbn of a maan posfrlon of a etar to
an awarenf positbn (used 10 asoount for shortterm
VaI’fatiOiIs In the precessbn, rrutatlon,
aberratbn, and parallax).
Baseelfan year—See flctl:loue year.
bfensia acrean-A photographic negative
COntafnlffg a Conrposfte of two dot screens, with
Ihe screen angles oriented 30° apart. These
screens are used to Mint tones of color for chart
features wffh thin lines.
MIL-HDBK-850
Bllby steel towar-A triangulation lower
mnaisting of two steel tripde, one wifhin the
other. Tha inner tripod holds the Instrument
platform, and the outer tr@od holds Ifw
obsarvets ptefform. me Sowwr can be easlfy
erected and as easily disassembled and moved
to a new location. See also ●urvey tower.
blmarghf forntat-The formal ol a map or
chart on which the cartograptric detail is
extanded to two edges of the sheet, rsxmelfy
north and east, thus Iaavlng onfy two margins.
Ss8 also blaed; bswedlng adge.
blnefy dlgft-kssfly called a Bit, a binary digtt
is the smahest unil of information which can be
s!ored In the computer. See also bit.
blrrocular vleion~imultaneous vision wilh
bolh eyes.
binocular-An optical instrumem tor use wilh
both eyes simultaneously.
bft map-A pattern of bits within a grid, stored
in memory, and used to generate an image on
a raster scan display.
blt plane-A gridded memory in a graphics
device used for storing informatkm for display.
Typically one cobr is ass’@rad to each bfi plane
tor dk.pfay.
bll-A binary digit.
bhrarlate normal dial rlbrstlon funct lon—
Mathematical function describing the behavior
of two dimensional random errors (e ,g., latitude,
longitude; x, x casting, norfhlng). Also called
circular normal dlatrlbUtlOn.
blackbody-An Meal surlace or body that
mmplefely absorbs all radiant energy tafting
upon it. Blacfdndies are used as models in the
design and calibration of renmte eenaing
systems.
tslaza-A mark made upon a tree trunk USUaffy
al about breast height. The bark and a small
amoum of tfre five wood are removed with an
axe or other cutting tool, faevlng a flat,
smoothed surfecs which Iorever brands the tree.
On rough-berked tree monuments or bearing
trees the appropriate marks are ecrfbad into a
smooth, narrow, vertical blaze the bwer end of
whkh is about 6 inches above the root crown.
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