1 - NGA

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errore.
mean sum--see flctltlous sun.
mean tide level (MTL)-The reference
plane midway between mean high wafer and
mean bw water. Also called half tide level;
ordlne~ tide level.
mean time-see mean solar ilme.
MIL-HDBK-850
meender corner—A corner eslablishedat the
infersecfionot standard, township, orsecfion
Iineswifhtha maanclar line near banksol
navigable straams or any meanderable body of
water.
meander llna—A traverse of the margin of a
parmsnenf natural body of waler, along Ihe
locus of the bank or shoreline at the elevation of
maan or ordinary high watar, upon which bank
or shoreline a riparian right may be predicated,
measured ang le—An angle as read directly
from an Instrumental observation and without
any application of corrections for focal
conditions. A measurad angle which has been
wrrecfed for local conditions only at the point of
observation is considered as an obsemed angle.
mechanical arm templet—See spider
templet.
mechanical-tampfet plot—See
mechan\cel.temp\et triangulation.
mechanical-temfslet trlanoulatlon—A
graphkal radtal triangulation u~ng slotted,
spider, or any form of mechanical templel. Also
called machanlcal-templet plot.
mechanical-templet—Any templel which is
manipulated and adjusted mechanically In
laying out a radial triangulafiin,
madlum.scale map-(JCS) A map having a
scale larger than 1:600,000 and smaller than
1:75,000. See stlao map.
megabyte (MB)—A unit of memory. One
megabyte equale 1,04S,576 bytes or
approximately one million byfes.
mamorlal—A durable article deposited in the
ground at the position of a corner 10 perpetuate
that position should the rnonumenl be removed
or destroyed. The memorial is usually deposited
160
al Ihe base of the monumem and may cortsisf
of anything durable such as glass or storwware,
a marked stone, charred stake, or a quantify of
charcoal.
Mendenhall pendulum—An hrvariabla
pendulum, one-quarter meter in length, with a
vibration period of one-half second, composed
of a Ienticular-shaped bob on a thin atam,
swung in an airiight casa from whch the air haa
been largely exhausted.
menauratlon—1. The act, procaas, or arf of
meaauring. 2. That branch of mathematics
dealing with the determination of Iangfh, area,
or volume,
Mercator bearing—See rhumb baarlng.
Mercator charr-A charr on the Mercator
projection. This Is the charl commonly used for
marine navigation, Also called equatorial
cylindrical orfnomorphic chars.
Mercator dlrecflon-Horizontal direction of a
rhumb line, expressed as angular sfkstarwe from
a relerence direction. Also ca}led rhumb
dlrecllon.,
Mercator equal-araa map pro)ectlon-
See sinusoidal map projacflon.
Marcalor map projection—A conformal
map projection of the cylindrical type. Tha
Equator is represented by a stra”ghf line true to
scale; the geographic meridiana are represent ad
by parallel straight Iinespwperdicmlar to the fine
representing the Equaloc lhey are spaced
according to their distance apart at the Equator.
The geographic parallels are represented by a
second system of straight fines perpendkxlar to
the family of lines representing tha maridiana
and therelora parallel with Iha Equator.
Conformality is achievad by mathematical
analysis, the spacing of the parallels being
incraased with increasing distance fmm Ihe
Equator to conform wlfh tha expanding scale
along the parallels rasuffing from the meridians
being represented by parallel fines. Also called
equatorial cylindrical orfhomorphlc map
projection.
Mercator track-See rhumb Ilne.
Mercury datum—A worldwide geodafic
system derived from an analysis of data from
astrogeodelic, gravimetric, and salellite sources.
Results of this analysis provided a best-fitting