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MIL-HDBK-850
sphorfcal ●xcosa-l%e amount by which the
sum of the three arrgfes of a triangle on a
sphere axoeade 180”. In gaodatk work, in the
co~yfafbn of trisngbs, the difference between
s@r3rrd angfas and sphamidal angles is
generally nagfecfsd: Sph- angles are used,
and Lagarrdm’s thsorem ki applii to the
dsribution of the spherical excess. That is,
a~roximatefy ona-thd of the @mrical axcaaa
of a given spherical triangle is subtracted from
each angle of the triangle.
spharlcal hsrrnonks-Trigonometric terms
of an infhife .saries used to approximate a W*
or thraedkrransiortd furrcfbrr of ~t~ns w or
abeve the Earlh.
spherkal Ion- lens in whmh .s11euriacas
are segments of spheres.
spherical trlangk-The cbsed figure formed
when any three points on the surfece of e
s+rhare am ~kred by ems of great circles.
ctpherold junctlorr-An eccentuatsd line on e
VP or chart, separating Wo or more major
,.- grids which ere. based on d~eran! spheroids,
spheroid of referonc~See refarence
spheroid.
spheroidal angle-An angle between two
curves on e spheroid; meesured by the angle
between their tangents at the point of
intereeXiin.
spheroidal axcess—Tha amount by which
the sun of the three engbs of a O’iangle on a
spherokf exceeds 180”. see also spherical
excess.
spheroldsf trlangl*A triangle on tha
surlece of e sphamid.
rtphorold-1. (genetal) Any figure differing
slightly from a sphere. 2, (geodesy) A
mathematical figure cbsaly approaching the
geoid in form and size end used as a surface of
reference for geodetic surveys. In geodesy
spheroid and elf!!sokf are synonymous terms.
See ebu Afry ●pherold (afllpaold);
Australian Nstlonal apherold; Eaasel
sphorold (slllpsofd); Clarko spheroid
(olllpsold) of 1868; Cfarko cphorold
(olllpsold) of 16S0; ●flipsofd of rotetlon:
equilibrium ●pherofd; Everest spheroid
(ellipsoid); Hayford sphorold (ellipsoid);
za8
Intorrmtlorml ●phoroid (alllpsold);
Kraaovaky sphtsrold (alllpaold); oblato
●pherold: prolsto ●pharold; roferanco
●pharold.
●phoropotm!tlal surtaca-See apharop.
●pharop-An aqu”~tential surface in the
normal gravily field of lhe Earlh. Also celled
●phoropotmtlal ●urtaca.
spldor tempfet—A mechanical templet which
is fwmed by afteching skoftad steal arms,
representing radiifs, to a central sore. The
spider tenqdet san be d~ernblad ard the
parts used agein. Also called mechanical arm
templet.
spider-tomplmt p}ot-See spldcr-tomplot
triangulation.
spldar-tamplet trienguletlon—A grephicsl
rad!al triangulation made by the uss of spider
Iempbts. Also called spider-tempfet plot.
spiral curve-(mufe surveying) A cutve of
uniformly vsrying radius mnnacfing a circuler
curve and e tangent, or two circular curves
whose rsdii sm. rqtiivaty, bngar and ahorler
than its own extreme radii. Afso called
easamont curve; tranaltlon curve,
spiral to spiral (SS)-A common point
between two spirals.
splrlt Iavel axis—The fine tangent to the
surfece of a spiril Ieval tube (vial) egainsf which
the bubble forms, at the center of the gmduetad
scale of the level, and in the plane of the
bngiwdinsl axis of the tube (vie!) and its center
of curvature. Also called axis of lava~ axle
of Iho level bubble; bubble ●xk.
splrft Ieval wind-Lack of parallelism
between the axis of a spirit Iavel vial and the fine
joining the centets of its suppals. When wind
(pronounced to rhyme with find) is prasant, the
bubble will respoti with a bngitudinal
movemenl Wren the spirit level is rocked on ifs
Suppotis.
nplrlt bvallng—The determination of
Islevetions
of points wfih respect to each otfwr or
\ with respect to e cumrnorr datum, by use of a
Ileveling
rod end en instrument using a spiril
level to esteblish e horizontal fine et sight.