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"Dry Pile Electroscope." — Encyclopedia Britannica, 1893

Dry Pile Electroscope

"Dry Pile Electroscope." — Encyclopedia Britannica, 1893

"The dynamo has its field mangets F F magnetized by means of a small current flowing around a shunt circuit." — Hawkins, 1917

Dynamo

"The dynamo has its field mangets F F magnetized by means of a small current flowing around a shunt…

The armature of a dynamo machine by Brush Electric Company. The dynamo machine, now known as an electrical generator, is a device that converts mechanical energy into electrical energy.

Dynamo Machine

The armature of a dynamo machine by Brush Electric Company. The dynamo machine, now known as an electrical…

The dynamo machine, now known as an electrical generator, is a device that converts mechanical energy into electrical energy.

Dynamo Machine

The dynamo machine, now known as an electrical generator, is a device that converts mechanical energy…

"A shaft runs through the machine from end to end, carrying a pulley, P, at one end, a commutator, c, at the other end, and a wheel armature, R, at the middle. The armature carries eight or more helices of insulated wire, H H, connected in pairs. As the shaft is turned by the action of the belt upon the pulley, the armature and the commutator are turned with it." — Avery, 1895

Brush dynamo

"A shaft runs through the machine from end to end, carrying a pulley, P, at one end, a commutator, c,…

"Compound wound dynamo, used when better automatic regulation of voltage on constant pressure circuits is desired than is possible with the shunt machine." — Hawkins, 1917

Compound wound dynamo

"Compound wound dynamo, used when better automatic regulation of voltage on constant pressure circuits…

"Where a motor is connected with the electric circuit of a dynamo...and the armature of the dynamo is rotated by mechanical power in opposition to the electromagnetic force, an electric current is generated, which tranverses the motor and causes its armature to rotate..." -Atkinson 1903

Connected dynamo and motor

"Where a motor is connected with the electric circuit of a dynamo...and the armature of the dynamo is…

"Separately excited dynamo. Current for field excitation is supplied by a second and smaller generator." — Hawkins, 1917

Seperately excited dynamo

"Separately excited dynamo. Current for field excitation is supplied by a second and smaller generator."…

"The electromagnet that supplies the flux of force must have a current to excite it. This current is sometimes supplied from an outside source. Such a dynamo is said to be seperately excited. Often all of the current from the armature is carried around the coils of the field magnet, thus forming a series dynamo." — Avery, 1895

Series dynamo

"The electromagnet that supplies the flux of force must have a current to excite it. This current is…

"Series wound dynamo, used for series aarc lighting, and as a booster for increasing the pressure on a feeder carrying current furnished by some othe generator." — Hawkins, 1917

Series wound dynamo

"Series wound dynamo, used for series aarc lighting, and as a booster for increasing the pressure on…

"The shunt wound dynamo differes from the series wound machine, in that an independent circuit is used for exciting its field magnet." — Hawkins, 1917

Shunt dynamo

"The shunt wound dynamo differes from the series wound machine, in that an independent circuit is used…

"When a dynamo is so constructed that only a smal part of its current is employed to magnetize its field-magnet, it is called shunt wound, because the magnetizing current is diverted from the main circuit through a shunt circuit." -Atkinson 1903

Shunt Wound Dynamo

"When a dynamo is so constructed that only a smal part of its current is employed to magnetize its field-magnet,…

An edgewise switchboard ammeter.

Edgewise Switchboard Ammeter

An edgewise switchboard ammeter.

Portrait of Thomas Edison

Thomas A Edison

Portrait of Thomas Edison

(1847-1931) Famous American inventor.

Thomas Alva Edison

(1847-1931) Famous American inventor.

"ABC is a horizontal coil of wire terminating at the binding screws a, b. FG is a ring-shaped trough of mercury for the sliding contacts. A wire connects the mercury with the binding screw d. DE is an upright support screwed into a metal base D in connection with the binding screw c, and terminating above in a mercury cup E. When required, DE can be replaced by the shorter supports D'E' and D"E". HLK is a support for a screw L, which carries an adjustible center." — Encyclopedia Britannica, 1893

Electric Apparatus

"ABC is a horizontal coil of wire terminating at the binding screws a, b. FG is a ring-shaped trough…

Rapid transit in which electricity is the motive power.

Electric Car

Rapid transit in which electricity is the motive power.

The System of Incandescent Lights is a device in which electric light is obtained by conducting a current of electricity through a resisting medium, as a gas or a carbon wire.

System of Incandescent Lights

The System of Incandescent Lights is a device in which electric light is obtained by conducting a current…

Tungsten incandescent lamp.

Electric Light, Tungsten Incandescent Lamp

Tungsten incandescent lamp.

Thomas Edison's original concept of the electric machine, an electricity generator distributed to homes, businesses, and factories.

Electric Machine

Thomas Edison's original concept of the electric machine, an electricity generator distributed to homes,…

An insulator is a material that resists the flow of electric current. An insulating material has atoms with tightly bonded valence electrons. These materials are used in parts of electrical equipment, as insulation. The term is also used to refer to insulating supports that attach electric power transmission wires to utility poles. Some materials such as glass, paper, or Teflon are very good electrical insulators.

Electric Wire Insulator

An insulator is a material that resists the flow of electric current. An insulating material has atoms…

"Various methods have been devised for measuring electrostatic quantity, one of the simplest of which is with the Kinnersley electrical air-thermometer. When a spark passes between the balls within the larger tube, the confined air is expanded, and the liquid column in the smaller communicating tube rises, and thus approximately indicates the quantity of the charge." — Avery, 1895

Kinnersley electrical air-thermometer

"Various methods have been devised for measuring electrostatic quantity, one of the simplest of which…

This illustration shows the field between two equally and oppositely charged spheres, mapped out by lines of force.

Electricity

This illustration shows the field between two equally and oppositely charged spheres, mapped out by…

This illustration represents the field between two equal positive charges; in this case the lines of force do not pass from one to the other, but travel off to an infinate distance.

Electricity

This illustration represents the field between two equal positive charges; in this case the lines of…

This illustration shows the lines of force when a positive charge equal to 4 at A, and a negative charge of 1 at B, are used. A being numerically stronger than B, lines starting from A will not fall on B, but pass off to infinate distance.

Electricity

This illustration shows the lines of force when a positive charge equal to 4 at A, and a negative charge…

This illustration shows the field of force due to a charge 1 at A, and a like charge 4 at B.

Electricity

This illustration shows the field of force due to a charge 1 at A, and a like charge 4 at B.

This illustration shows the field of force between two parallel planes. At the edges its lines of foce curve out. Some pass from the back of one plane to the back of the other.

Electricity

This illustration shows the field of force between two parallel planes. At the edges its lines of foce…

A is a positively charged conductor and B represents the equal and oppsite charge. When the conductor C is introduced into the field, some of the lines of force are divided, since they cannot exist in a conductor.

Electricity

A is a positively charged conductor and B represents the equal and oppsite charge. When the conductor…

An example of electricity: early galvanometer.

Electricity

An example of electricity: early galvanometer.

Electrical incandescent light bulb.

Incandescent

Electrical incandescent light bulb.

"An electromagnet is a bar of iron magnetized by an electric current, substantial as just shown." — Avery, 1895

Electromagnet

"An electromagnet is a bar of iron magnetized by an electric current, substantial as just shown." —…

"When an electromagnet is U-shaped, the coils around the two ends of the bent iron core are so wound that if the coil should be straightened either coil would appear as a continuation of the other, i.e., the current would circle around the core in the same direction in the two coils. Such magnets are often made by connecting an end of the core of one spool-shaped magnet, by a straight soft iron bar called a yoke." — Avery, 1895

Electromagnet

"When an electromagnet is U-shaped, the coils around the two ends of the bent iron core are so wound…

"A magnet which owes its magnetic properties to the inductive action of an electric current." -Whitney, 1911

Electromagnet

"A magnet which owes its magnetic properties to the inductive action of an electric current." -Whitney,…

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…

An electrical instrument consisting of two plates, which can produce a spark.

Electrophotus

An electrical instrument consisting of two plates, which can produce a spark.

Apparatus for showing the presence of electricity without giving quantitative measurements.

Electroscope

Apparatus for showing the presence of electricity without giving quantitative measurements.

"The electroscope is an instrument for detecting and testing electrification. A metallic rod passes through the cork of a glass vessel, and terminates on the outside in a ball or a disk. The lower end of the rod carries two strips of gold-leaf or of aluminum foil that hang parallel and close together. When an electrified object is brought near the knob or into contact with it, the metal strips below become similarly charged and are, therefore, mutually repelled." — Avery, 1895

Electroscope

"The electroscope is an instrument for detecting and testing electrification. A metallic rod passes…

"Discharging Electroscope" — Encyclopedia Britannica, 1893

Electroscope

"Discharging Electroscope" — Encyclopedia Britannica, 1893

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end by a light pith-ball, which is covered with gold leaf, and supported horizontally at its centre by a fine point.." -Comstock 1850

Electroscope

"One of the simplest instruments of this kind consists of a metallic needle, terminated at each end…

"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…

"In the gold-leaf electroscope (invented by Bennet in 1787), two light strips of gold-leaf hang from the lower end of a metal rod, which passes vertically through an opening in the top of a glass bottle and expands above into a plate. If a piece of rubbed sealing-wax or other electrified body be brought near the plate, the gold leaves will repel each other and diverge ... A cylinder of wire gauze placed just inside the glass case, improves the action of the instrument." -Hazeltine, 1894

Gold Leaf Electroscope

"In the gold-leaf electroscope (invented by Bennet in 1787), two light strips of gold-leaf hang from…

"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…

Conductor for electricity.

Simple Electroscope

Conductor for electricity.

Device for electrostatic induction.

Electrostatic Induction

Device for electrostatic induction.

Elliot's Astatic Galvonometer.

Elliots Astatic Galvonometer

Elliot's Astatic Galvonometer.

"Equipotential Lines about two similarly electrified spheres, A and B, the quantities of electricity being as 2:1. The lines of force are also shown radiating from the spheres." -Whitney, 1911

Equipotential

"Equipotential Lines about two similarly electrified spheres, A and B, the quantities of electricity…

"This apparatus shows the rotation at once of a magnet and of a movable conductor. The rotating pieces are the magnet sn, which is tied to the copper peg at the bottom of G by means of a piece of string, and swims round the vertical current buoyed up by the mercury in G, and the wire DE, which is hinged to D by a thin flexible wire, and swims round the pole of the vertical magnet n's'." — Encyclopedia Britannica, 1893

Faraday Apparatus

"This apparatus shows the rotation at once of a magnet and of a movable conductor. The rotating pieces…

"Faraday used in his experiments two identical pieces of apparatus, which were vertually two spherical Leyden jars. The outer coating EF was divided into two hemispheres, which could be fitted together airtight. The lower hemisphere F was fitted to a perforated stem, provided with a stop-cock G, so that it could be screwed to an airpump while the apparatus was being exhausted, and afterwards screwed into a foot H. The upper hemisphere was pierced by a tube, into which was cemented a shellac plug B. C is a metal wire passing down through B, which supports the hollow metal sphere D, forming the inside armature, and carries the metal ball A, by means of which D can be charged and discharged." — Encyclopedia Britannica, 1893

Faraday Experiment

"Faraday used in his experiments two identical pieces of apparatus, which were vertually two spherical…

"Machines of this kind may be constructed with as many pairs of plaes, combs, and brushes as can be conveniently combined together; four-plate machines being common, in which the relative positions of each pair of plates are reversed, as shown..." -Atkinson 1903

Four-Plate Machine

"Machines of this kind may be constructed with as many pairs of plaes, combs, and brushes as can be…

Franklin experimenting with electricity.

Franklin

Franklin experimenting with electricity.

(1706-1790) US diplomat, inventor, politician, and printer

Dr. Benjamin Franklin

(1706-1790) US diplomat, inventor, politician, and printer

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove, lighting rod and bifocal glasses. Served in the Constitutional Convention of 1787

Dr. Benjamin Franklin

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove,…

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove, lighting rod and bifocal glasses. Served in the Constitutional Convention of 1787

Dr. Benjamin Franklin

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove,…

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove, lighting rod and bifocal glasses. Served in the Constitutional Convention of 1787

Dr. Benjamin Franklin

(1706-1790) United States diplomat, inventor, politician, and printer. Invented the Franklin stove,…

A profile of Benjamin Franklin

Benjamin Franklin

A profile of Benjamin Franklin

A portrait of Benjamin Franklin. Born in 1706 and died in 1790.

Benjamin Franklin

A portrait of Benjamin Franklin. Born in 1706 and died in 1790.

Now known as electrostatic generators, the Frictional electric machine produces static electricity at high voltage. "A, glass plate; B, rubber, holding amalgam; C, collecting points; D, prime conductor." -Whitney, 1911

Frictional Electric Machine

Now known as electrostatic generators, the Frictional electric machine produces static electricity at…

An Edison fuse plug and casing for switchboard use.

fuse plug and casing

An Edison fuse plug and casing for switchboard use.

A galvanometer is a type of ammeter; an instrument for detecting and measuring electric current. It is an analog electromechanical transducer that produces a rotary deflection, through a limited arc, in response to electric current flowing through its coil. The term has been expanded to include uses of the same mechanism in recording, positioning, and servomechanism equipment.

Galvanometer

A galvanometer is a type of ammeter; an instrument for detecting and measuring electric current. It…