1 - NGA

I
I
I
update, corrplefe, or density the date content.
psth—l%e project-km of the orbffal pfans d the
mtetliie m the, Earth’s surfaoe: the bcue CI ti
satellite eubpomt.
MIL-HDBK-850
PC ARC/lNFO-A vector data, rafatienal
geegrsphii infonnetii syetam for a peraonel
SUWtdW. Produd by Environmental systems
Reeaemh Institute 8$ e Iew-and GIS.
PC-1OOO camore-A trade name for a
Qacdetk stellar sarnare having a focal length of
1,000 mm.
Peeus.allicw Invbraor+ cf.ms of inveraor
pnwiding a mectumicel eelutiin for tha linear
end angular elements of rectifiition, Also called
scissors Nrvorsor.
Poaucolller-Cerpantler lnvarsor— A
modified Cepsnfier invemor coupled to the
finkage system of a Paeucalfier invarecr to
provide e mechanical means of sofvhg the
linear and engufar elements ef rectif@atian.
peel—(negative engraving) A t~hnique of
removing the opaque stratum from hs
W+K@K! bese. Peeling between etched
ouihne Images prcdume a negative; psefing
oulskje of the etchd outfine images pmdwes a
positive. See also mask, definitbn Z.
pbepslght slldade-A type of aliiede
ocmeisting of e peep sight mountsd on a
straightedge.
peepslght compass—The sights of s
%~~ f- by Mendeti with sfiis for a
stghtlng medium rather than a telescope.
peg sdjuetrnont-A method of adjusting a
Iaveliig Inalrument of the dumpy level type, to
make the fine of solfimetion pereflef with the axis
of the spirit level, and employing two stable
marks (pegs) the length et one instrument sight
epert, Also called 11/10 peg ●djuetmamt.
peg test-A method et testing the mlfirnstion
adjustment of a Ievefing instrument.
Pemborton Icvellng rod-A speaking rod
marked wffh affemate mws of circular and
dlernond-shaped dots, running diegonq!ly
ecmse the rod. Read to hundredths ef a foot.
pendulum ●lidade-A telescopk elidede in
184
which a pendulum dev”- replecee the
mnventional bubbfe for mtabfiehing a horizontal
reference fine from whiih verficaf angles may be
measured.
pendulum mstrolabe-An astronomic
instrument ushg e constant attitude for poeitii
datarmimdii. fts distinctive feature is a mirror
~~~ On t~ of e pandufum tO fOrrn the
arbfii horizon.
pendulum lovef-A Ievefing instrument in
whiih the line d eight is euferrmticelly
maintained hcrisordnl bf mswms d a bdf-in
pendulum &v&e. Afm callad ●utomatic
Ievof.
pendulum—1. In general, a body sc
suspended es to swing frardy to end fro under
the influence ef gravity and rnementum. 2. A
verl”-1 bar so stswc+&5 from Mow by a stiff
spring as to vibrate to and fm under tha
combkd actien of gravity and the r@oring
force of the epring. See else compound
pendulum; dummy pendulum; ?roeswlnglng
pendulum: Idle pandulum;
Invar pendulum; Invarlabls pandulum;
Menderthall pondutum; quarts . . .
pendulum; rsmalver; rekstlve pendulum:
reversible pendulum; simple pendulum;
working pendulum.
percent of enlargemenVreductlon—The
fecfor by which an original is to be enlarged or
reduced in rapmducfion. A 50 pement finesr
enlargement et a 4- by 54nch eriginal weuld be
Ginchss by 7 l/2-inches, whifa a 50 percent
reduction of the -me original would be 2-i~hes
by 2 l/2-inches. See alse ecale of raproductlon.
parcant of alop*See gradlant.
periapala—see perlcenter.
parleatron-That point of the orbit of ons
mersbsr of a deuble star system at whii the
stars are nearest togelher. Cpposite et
epeatron.
pericenter—fn en elfiiticel orbii the peint in
the orbit whiih is the nearest dIsfanca from the
focus where the affreofing mass is Ioceted. The
perkecder is al one end of the mmpr asie of the
ortital ellipse. Oppeeite et apoapsls;
epocentar; ●pofocue. Aieo csllsd
porlapels; perlfocua.