ClipArt ETC
An illustration of a balance scale.

Balance Scale

An illustration of a balance scale.

An instrument, usually resembling a pair of dividers or compasses with curved legs, for measuring the diameter or thickness of bodies, as of work shaped in a lathe or planer, timber, masts, shot, etc.

Micrometer Calipers

An instrument, usually resembling a pair of dividers or compasses with curved legs, for measuring the…

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining its kind. ... In Volta's condensing electroscope, in place of the gilt knob there is a flat metal plate upon which rests another similar plate, which may be removed by an insulating handle." -Whitney, 1911

Condensing Electroscope

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining…

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining its kind. ... The simplest electroscope consists of pith-balls suspended by silk threads." -Whitney, 1911

Pith-Ball Electroscope

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining…

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining its kind. ... Quadrant electroscope, a form of pith-ball electroscope which serves to measure roughly the degree of electrification by the rise of the pith-ball as indicated by the motion of the rod carrying it on a graduated semicircle." -Whitney, 1911

Quadrant Electroscope

"An instrument for observing or detecting the existence of free electricity, and, in general, for determining…

An instrument for measuring or testing.

Instrument Panel Gauge

An instrument for measuring or testing.

Any of various measuring instruments for measuring a quantity

General Purpose Meter

Any of various measuring instruments for measuring a quantity

A potentiometer instrument for measuring the potential (or voltage) in a circuit taps off a fraction of a known voltage from a resistive slide wire and compares it with the unknown voltage by means of a galvanometer. The sliding tap of the potentiometer is adjusted and the galvanometer briefly connected to both the sliding tap and the unknown potential; the deflection of the galvanometer is observed and the sliding tap adjusted until the galvanometer no longer deflects. At that point the galvanometer draws no current from the unknown source, and the magnitude of voltage can be calculated from the position of the sliding contact. This null balance method is a fundamental technique of electrical metrology.

Potentiometer

A potentiometer instrument for measuring the potential (or voltage) in a circuit taps off a fraction…

A device that measures the instantaneous speed of a land vehicle.

Multiple Use Speedometer

A device that measures the instantaneous speed of a land vehicle.

A flexible form of ruler. It consists of a ribbon of cloth, plastic, fiber glass, or metal strip with linear

Measuring Tape

A flexible form of ruler. It consists of a ribbon of cloth, plastic, fiber glass, or metal strip with…