1. One who, or that which, shows or points out; as, a fare indicator in
a street car.
2. (Mach.) A pressure gauge; a water gauge, as for a steam boiler; an
apparatus or instrument for showing the working of a machine or moving
part; as: (a) (Steam Engine) An instrument which draws a diagram
showing the varying pressure in the cylinder of an engine or pump at
every point of the stroke. It consists of a small cylinder
communicating with the engine cylinder and fitted with a piston which
the varying pressure drives upward more or less against the resistance
of a spring. A lever imparts motion to a pencil which traces the
diagram on a card wrapped around a vertical drum which is turned back
and forth by a string connected with the piston rod of the engine. See
Indicator card (below). (b) A telltale connected with a hoisting
machine, to show, at the surface, the position of the cage in the shaft
of a mine, etc.
<! p. 752 !>
3. (Mech.) The part of an instrument by which an effect is indicated,
as an index or pointer.
4. (Zoöl.) Any bird of the genus Indicator and allied genera. See Honey
guide, under Honey.
5. (Chem.) That which indicates the condition of acidity, alkalinity,
or the deficiency, excess, or sufficiency of a standard reagent, by
causing an appearance, disappearance, or change of color, as in
titration or volumetric analysis.
The common indicators are litmus, tropæolin, phenol phthalein, potassic
permanganate, etc.
Indicator card, the figure drawn by an engine indicator, by means of
which the working of the engine can be investigated and its power
calculated. The Illustration shows one form of indicator card, from a
steam engine, together with scales by which the pressure of the steam
above or below that of the atmosphere, corresponding to any position of
the engine piston in its stroke, can be measured. Called also indicator
diagram. - - Indicator telegraph, a telegraph in which the signals are
the deflections of a magnetic needle, as in the trans- Atlantic system.
In"di*ca*to*ry (n"d*k*t*r; 277), a. Serving to show or make known;
showing; indicative; signifying; implying.
In`di*ca"trix (?), n. [NL.] (Geom. of Three Dimensions) A certain conic
section supposed to be drawn in the tangent plane to any surface, and
used to determine the accidents of curvature of the surface at the
point of contact. The curve is similar to the intersection of the
surface with a parallel to the tangent plane and indefinitely near it.
It is an ellipse when the curvature is synclastic, and an hyperbola
when the curvature is anticlastic.
||In`di*ca"vit (?), n. [L., he has indicated.] (Eng. Law) A writ of
||prohibition against proceeding in the spiritual court in certain
||cases, when the suit belongs to the common-law courts. Wharton (Law
||Dict. ).
||
In"dice (?), n. [F. indice indication, index. See Index.] Index;
indication. [Obs.] B. Jonson.
In"di*ces (?), n. pl. See Index.
||In*di"ci*a (?), n. pl. [L., pl. of indicium, fr. index an index.]
||(Law) Discriminating marks; signs; tokens; indications; appearances.
||Burrill.
||
In*dic"i*ble (?), a. [F.] Unspeakable. [Obs.]
In*dic"o*lite (?), n. [L. indicum indigo + -lite: cf. F. indicolithe.]
(Min.) A variety of tourmaline of an indigo-blue color.
In*dict" (-dt"), v. t. [imp. & p. p. Indicted (- dt"d); p. pr. & vb. n.
Indicting.] [OE. enditen. See Indite.]