"An instrument for measuring the strength of an electric current in amperes."-Whitney, 1902

Ampere-meter

"An instrument for measuring the strength of an electric current in amperes."-Whitney, 1902

The electrical symbol for a battery, either storage or dry cells.

Battery

The electrical symbol for a battery, either storage or dry cells.

An illustration of Mance's method used to measure battery resistance.

Battery Resistance

An illustration of Mance's method used to measure battery resistance.

An illustration of Mance's method used to measure battery resistance.

Battery Resistance

An illustration of Mance's method used to measure battery resistance.

An illustration of the assisting and opposing method used to measure battery resistance.

Battery Resistance

An illustration of the assisting and opposing method used to measure battery resistance.

A wet-cell battery composed of zinc in a copper sulfate solution.

Daniell's Battery

A wet-cell battery composed of zinc in a copper sulfate solution.

"Galvanism is the branch of electric science to which an experiment by Galvani gave birth. His wife, who was making soup from frogs, put them in proximity to a charged electrical machine. On touching them with a scalpel their legs became greatly convulsed. He came to the erroneous conclusion that animal electricity existed in the nerves and muscles of frogs, etc. His contemporary Volta inferred that the metals took the active part in producing the contraction, and the electricity was due to their contact. In 1800 he first described and constructed what has since been called the Voltaic pile."—(Charles Leonard-Stuart, 1911)

Galvanic Battery

"Galvanism is the branch of electric science to which an experiment by Galvani gave birth. His wife,…

"An electric bell consists mainly of an electromagnet, E, and a vibrating armature that carries a hammer, H, that strikes a bell. One terminal of the magnet coils is connected to the binding-post, and the other terminal to the flexible support of the armature. The armature carries a spring that rests lightly against the tip of an adjustable screw at C. This screw is connected to the other binding-post. The bell is connected to a battery of 2 or 3 cells in series, a key, a push-button, P, or some other device for closing the circuit being placed in the line." -Avery 1895

Electric Bell

"An electric bell consists mainly of an electromagnet, E, and a vibrating armature that carries a hammer,…

An illustration of the bottle bichromate.

Bottle Bichromate

An illustration of the bottle bichromate.

The cell was set up in a glass, or glazed earthenware, pot. This contained the chromic acid solution, the carbon plate and a porous pot. Inside the porous pot was dilute sulfuric acid, the zinc rod, and a small quantity of mercury. The mercury formed an amalgam with the zinc and this reduced "local action", i.e. unwanted dissolution of the zinc when the cell was not in use.

Fuller Bichromate

The cell was set up in a glass, or glazed earthenware, pot. This contained the chromic acid solution,…

An illustration of the Trouve bichromate.

Trouve Bichromate

An illustration of the Trouve bichromate.

This receptacle consists of the metal box designed for connections to a wiring system.

Outlet Box

This receptacle consists of the metal box designed for connections to a wiring system.

The high cost and low top speed of electric vehicles compared to later internal combustion vehicles caused a worldwide decline in their use.

Electric Carriage Type Vehicle

The high cost and low top speed of electric vehicles compared to later internal combustion vehicles…

A cartoon of a man being blown away by an electric fan.

Cartoon of Man Being Blown Away by Fan

A cartoon of a man being blown away by an electric fan.

Electric catfish is the common name for the catfish (order Siluriformes) family Malapteruridae. This family includes two genera, Malapterurus and Paradoxoglanis with 19 species. Several species of this family have the ability to produce an electric shock of up to 350 volts using electroplaques of an electric organ.  Electric catfish are found in tropical Africa and the Nile River. Electric catfish are usually nocturnal and feed primarily on other fish, incapacitating their prey with electric discharges.

Electric Catfish

Electric catfish is the common name for the catfish (order Siluriformes) family Malapteruridae. This…

An illustration of Bussen's cell.

Bussen's Cell

An illustration of Bussen's cell.

The Daniell cell (var. sp. Daniel cell), also called the gravity cell or crowfoot cell was invented in 1836 by John Frederic Daniell, who was a British chemist and meteorologist. The Daniell cell was a great improvement over the voltaic pile used in the early days of battery development. The Daniell cell's theoretical voltage is 1.1 volts and the chemical reaction is Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s).

Daniell Cell

The Daniell cell (var. sp. Daniel cell), also called the gravity cell or crowfoot cell was invented…

An illustration of Bussen's cell.The Grove cell was an early electric primary cell named after its inventor, British chemist William Robert Grove, and consisted of a zinc anode in concentrated sulfuric acid and a platinum cathode in concentrated nitric acid, the two separated by a porous ceramic pot. The Grove cell was the favored power source of the early American telegraph system in the period 1840 - 1860 because it offered a high current output and higher voltage than the earlier Daniell cell (at 1.9 volts and 1.1 volts, respectively).

Grove Cell

An illustration of Bussen's cell.The Grove cell was an early electric primary cell named after its inventor,…

Georges Leclanché invented and patented in 1866 his battery, the Leclanché cell. It contained a conducting solution (electrolyte) of ammonium chloride, a cathode (positive terminal) of carbon, a depolarizer of manganese dioxide, and an anode (negative terminal) of zinc. The Leclanche battery was essentially a self-contained version of an earth battery, and fairly copied its design.

Leclanché Cell

Georges Leclanché invented and patented in 1866 his battery, the Leclanché cell. It contained…

An illustration of the Minotto cell.

Minotto Cell

An illustration of the Minotto cell.

An electric or manual drill, which has jaws and a collar that is tightened to grip and hold the drill bit.

Drill Chuck

An electric or manual drill, which has jaws and a collar that is tightened to grip and hold the drill…

An electric vacuum cleaner.

Electric Vacuum Cleaner

An electric vacuum cleaner.

The electrical symbol for a coil which surrounds an iron core but very seldom used on delco drawings.

Coil

The electrical symbol for a coil which surrounds an iron core but very seldom used on delco drawings.

The electrical symbol for a coil where there is no chance of confusion.

Coil

The electrical symbol for a coil where there is no chance of confusion.

"A vertical conductor carrying an electric current, and surrounded by a magnetic line of force, which is in turn surrounded by electric whirls; the magnetic line of force is an electric vortex-ring." — Avery, 1895

Vertical conductor

"A vertical conductor carrying an electric current, and surrounded by a magnetic line of force, which…

The electrical symbol for contact points such as switches or distributors.

Contact Points

The electrical symbol for contact points such as switches or distributors.

"...shows especially the construction of the series wound dynamo. The armature consists of a circular magnet mounted between two massibe pole-pieces belonging to the stationary magnet, by which it is partly inclosed, sufficient space being left on each side for it to revolve freely without contact." -Atkinson 1903

Series Wound Dynamo

"...shows especially the construction of the series wound dynamo. The armature consists of a circular…

"Thus, if we suppose the conducting wire be placed in a vertical situation, as shown, and p, n, the current of positive electricity to be descending through it, from p to n, and if throught the point c in the wire in the plane NN be taken, perpendicular to p, n, that is in the present case a horiczontal plane, then if any number of circles be described in that plane, having c for thier common centre, the action of the current on the wire on upon the north pole of the magnet, will be to move it in a direction corresponding to the motion of the hands of a watch, having the dial towards the positive pole of the battery." -Comstock 1850

Circular Motion of the [Electric] Fluid

"Thus, if we suppose the conducting wire be placed in a vertical situation, as shown, and p, n, the…

"The electric furnace is a device by which a very high temperature is obtained by using a large arc between carbon terminals. The arc consists of carbon vapor, which conducts the current over the gap between the carbons and the resistance is so great that much heat is developed." -Brownlee 1907

Electric Furance

"The electric furnace is a device by which a very high temperature is obtained by using a large arc…

Mechanism of Apollo Electric Horn.

Electric Horn

Mechanism of Apollo Electric Horn.

"An electric motor that uses a square nut to engage the electromagnet which drive the motor." -Avery 1895

Electric Motor

"An electric motor that uses a square nut to engage the electromagnet which drive the motor." -Avery…

"The electric screen. A screen of wire gauze surrounding a delicate electrical instrument will protect it from external electrostatic induction." -Hawkins, 1917

Electric Screen

"The electric screen. A screen of wire gauze surrounding a delicate electrical instrument will protect…

"Path of current through person receiving a shock from the fame of a machine insulated from ground. (There is an accidental tree ground on the line and a accidental ground in the winding of the machine.)." —Croft 1920

Electric Shock

"Path of current through person receiving a shock from the fame of a machine insulated from ground.…

"Electric-bell indicator for fishing [when installing home wiring systems]." —Croft 1915

Electric-bell Indicator

"Electric-bell indicator for fishing [when installing home wiring systems]." —Croft 1915

A fixture, usually pendent from the ceiling, for holding electric lamps. The word is analogous to chandelier, from which it was formed.

Early Design Electrolier

A fixture, usually pendent from the ceiling, for holding electric lamps. The word is analogous to chandelier,…

An illustration of a quadrant electrometer. An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical hand-made mechanical instruments to high-precision electronic devices.

Quadrant Electrometer

An illustration of a quadrant electrometer. An electrometer is an electrical instrument for measuring…

Alessandro Volta's design of the electrophorus. "An instrument for obtaining statical electricity by means of induction." -Whitney, 1911

Electrophorus

Alessandro Volta's design of the electrophorus. "An instrument for obtaining statical electricity by…

An electrical instrument used for measuring electric charge.

Electroscope

An electrical instrument used for measuring electric charge.

Elliot's Astatic Galvonometer.

Elliots Astatic Galvonometer

Elliot's Astatic Galvonometer.

"When a charge is moved from any point to another point in the same equipotential surface, no work is done upon it. When a charge is moved from one such surface to another, the work done is independent of the path of transfer. If such a surface was to be rendered impenetrable, a particle could lie upon it without tendancy to move along it in any direction. If any two points in such a surface were to be joined by a conductor, no flow of electrification would take place. The closed lines are equipotential lines drawn, upon equipotential surfaces, about two similartly electrified spheres, the quantity of electrifaction at A being twice that at B." -Avery 1895

Equipotential Lines

"When a charge is moved from any point to another point in the same equipotential surface, no work is…

An illustration of the foster method, used to measure electric current.

Foster's Method

An illustration of the foster method, used to measure electric current.

Any furnace in which the heat is provided by an electric current

Electric Furnace

Any furnace in which the heat is provided by an electric current

"The galvanometer is an instrument for determining the strength of an electric current by means of the deflection of a magnetic needle around which the current flows. When a galvanoscope is provided with a scale so that the deflections of its needle may be measured, it becomes a galvanometer." — Avery, 1895

Astatic galvanometer

"The galvanometer is an instrument for determining the strength of an electric current by means of the…

Galvanometer designed by Professor Maxwell.

Galvonometer

Galvanometer designed by Professor Maxwell.

An illustration of an idiostatic gauge which determines the charge in the condenser.

Idiostatic Gauge

An illustration of an idiostatic gauge which determines the charge in the condenser.

The electrical symbol for a generator, commutator, and brushes.

Generator

The electrical symbol for a generator, commutator, and brushes.

An electric generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities.

Electric Generator

An electric generator is a device that converts mechanical energy to electrical energy. The reverse…

The electrical symbol for a ground connection.

Ground Connection

The electrical symbol for a ground connection.

Device which radiates heat, ideally used to raise temperature by means of electrical power.

Electric Heater

Device which radiates heat, ideally used to raise temperature by means of electrical power.

An illustration of an arc electric lamp or an arc lamp which produces light by an electric arc.

Arc Electric Lamp

An illustration of an arc electric lamp or an arc lamp which produces light by an electric arc.

"Lenz's apparatus for measuring the heat given off by an electric current." -Hawkins, 1917

Lenz's Apparatus

"Lenz's apparatus for measuring the heat given off by an electric current." -Hawkins, 1917

The electrical symbol for lighting switches.

Lighting Switch

The electrical symbol for lighting switches.

An illustration of the loss of charge method.

Loss of Charge Method

An illustration of the loss of charge method.

"The essential parts of an ordinary Wimshurst machine, are two ordinary drums. On each plate are fixed a large number of strips of conducting material which are equal in size and are equally spaced, radially if on a plate, and circumferentially if on a drum." — Hawkins, 1917

Wimshurst Electric Machine

"The essential parts of an ordinary Wimshurst machine, are two ordinary drums. On each plate are fixed…

"Oersted's experiements are illustrated...which shows, at A, B, C and D, the four different positions which a balanced magnetic needle tends to assume when placed parallel to a wire through wich an electric current is flowing in the different directions indicated by the arrows..." -Atkinson 1903

Deflection of te Magnetic Needle by the Electric Current

"Oersted's experiements are illustrated...which shows, at A, B, C and D, the four different positions…

"The Metre Bridge is employed - a piece of apparatus which is illustrated [here]. It consists of a wooden base, upon the upper face of which is mounted a metallic rectangle; three sides of this rectangle are formed by a broad substantial copper band - having a negligible resistance - and the fourth consists of a platinum silver wire w w joining the copper blocks P and p. This wire is exactly one meter long, and over it slides a key K, which when depressed makes contact by means of a platinum knife-edge with the wire; the exact point on the wire at which this contact is made is indicated by an arrow-head on the key, which slides against a scale, as shown." (Britannica, 1891)

Metre Bridge

"The Metre Bridge is employed - a piece of apparatus which is illustrated [here]. It consists of a wooden…

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…

This n electric generator is a device that converts mechanical energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor.

Power Generator

This n electric generator is a device that converts mechanical energy to electrical energy. The reverse…

"It is remarkable for an electric battery situated between the pectorals and head and gills; this is indicated by two elevations extending along the back, and consists of numerous cells formed like honeycomb, this being, as is the similar provision of the <em>Gymnotus</em> or electric eel, amply supplied with nerves. On being touched the animal imparts a severe electric shock, sufficient to stun its prey." &mdash; Goodrich, 1859

Electric Ray

"It is remarkable for an electric battery situated between the pectorals and head and gills; this is…

A diagram of Thomson's replenisher.

Diagram of Thomson's Replenisher

A diagram of Thomson's replenisher.