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A plate with an opening, which is generally circular, used in instruments to cut off marginal portions of a beam of light, as at the focus of a telescope.

An instrument for examining the thermal resistance or heat- conducting power of liquids.

An instrument for examining the dichroism of crystals.

A telephonic instrument for office or other similar use, having a sound-magnifying device enabling the ordinary mouthpiece to be dispensed with. Much use has been made of it for overhearing, or for recording, conversations for the purpose of obtaining evidence for use in litigation.

spade or a hoe; to open, loosen, or break up (the soil) with a spade, or other sharp instrument; to pierce, open, or loosen, as if with a spade. Be first to dig the ground. Dryden.

An instrument for measuring the dilatation or expansion of a substance, especially of a fluid.

An instrument for expanding a part; as, a urethral dilator.

An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc.

An instrument for determining the time of apparent noon. It consists of two mirrors and a plane glass disposed in the form of a prism, so that, by the reflections of the sun's rays from their surfaces, two images are presented to the eye, moving in opposite directions, and coinciding at the instant the sun's center is…

An instrument used for double writing, as one for producing embossed writing for the blind and ordinary writing at the same time. -- Dip`lo*graph"ic*al (#), a. -- Dip*log"ra*phy (#), n.

A part of a machine or instrument which directs its motion or action.

One who, or that which, discharges. Specifically, in electricity, an instrument for discharging a Leyden jar, or electrical battery, by making a connection between the two surfaces; a discharging rod.

An instrument for dividing lines, describing circles, etc., compasses. See Compasses.

s; graduating. Dividing engine, a machine for graduating circles (as for astronomical instruments) or bars (as for scales); also, for spacing off and cutting teeth in wheels. -- Dividing sinker. (Knitting Mach.). See under Sinker.

ith, teaching. The word of God serveth no otherwise than in the nature of a doctrinal instrument. Hooker.

f anything else; -- in its most extended sense, including any writing, book, or other instrument conveying information in the case; any material substance on which the thoughts of men are represented by any species of conventional mark or symbol. Saint Luke . . . collected them from such documents and testimonies as he…

A small point or spot, made with a pen or other pointed instrument; a speck, or small mark.

An instrument for augmenting a very small quantity of electricity, so as to render it manifest by sparks or the electroscope.

A steel instrument for completing the dressing of soft stone.

or produce, as a line on any surface; hence, also, to form by marking; to make by an instrument of delineation; to produce, as a sketch, figure, or picture.