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"Thomson's absolute electrometer is an adaptation of the attracted disc principle for absolute determinations. We give merely an indication of its different parts, referring to Thomson a paper for details." — Encyclopedia Britannica, 1893

Absolute Electrometer

"Thomson's absolute electrometer is an adaptation of the attracted disc principle for absolute determinations.…

"The gold leaves are gummed on the two sides of a flat piece of metal carried by a stout stem, which passes through the top of a glass shade and ends in a flat disc. By means of this disc we may convert the instrument into Volta's condensing electroscope." — Encyclopedia Britannica, 1893

Bennets Electroscope

"The gold leaves are gummed on the two sides of a flat piece of metal carried by a stout stem, which…

"Cavallo's electroscope embodies the double pendulum principle. It consists of two fine silver wires loaded with small pieces of cork or pith, and suspended inside a small glass cylinder. Through the cap which closes the cylinder passes the stout wire from which the pendulums are suspended. This wire ends in a thimble-shaped dome A, which comes down very nearly to the cap; the outside of the cap is part of the wire and covered with sealing wax, and the object of the dome is to keep moisture from the stem, so that the electroscope could be used in the open air even in rainy weather." — Encyclopedia Britannica, 1893

Cavallos Electroscope

"Cavallo's electroscope embodies the double pendulum principle. It consists of two fine silver wires…

An electric condenser made out of electric plates.

Electric Condenser

An electric condenser made out of electric plates.

"D is a needle, formed of light silver wire, suspended by a fine glass fiber, from a torsion head A. Below the needle is a piece of sheet metal NE, divided half through by a notch in the middle, and then bent in opposite directions on both sides of the notch, so that, when looked at end on, it appears like a Y." — Encyclopedia Britannica, 1893

Dellman's Electrometer

"D is a needle, formed of light silver wire, suspended by a fine glass fiber, from a torsion head A.…

"C is an insulated disc, over which is suspended another disc, hung from the arm of a balance, and connected with the earth. A weight w is put in a scale attached to the other arm of the balance. The insulated disc is connected with the internal armature B of a Leyden jar, whose outer armature is in connection with the suspended disc, Electricity is conveyed to B, and the quantity q measured by a small Lane's jar A, until the electric attraction at C is just sfficient to turn the balance." — Encyclopedia Britannica, 1893

Disc Electrometer

"C is an insulated disc, over which is suspended another disc, hung from the arm of a balance, and connected…

"Distrbution of electrification on a charged hollow sphere. If an insulated conductor d be inserted through the opening in the sphere and brought in contact with the interior surface and afterwards carefully removed, it will be found, by testing with the gold leaf electroscope, tat it has recieved no charge. If touched to the outside, however, the conductor will recieve part of the charge." -Hawkins, 1917

Distribution of Charge

"Distrbution of electrification on a charged hollow sphere. If an insulated conductor d be inserted…

"Dry Pile Electroscope." — Encyclopedia Britannica, 1893

Dry Pile Electroscope

"Dry Pile Electroscope." — Encyclopedia Britannica, 1893

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…

An electrical instrument used for measuring electric charge.

Electroscope

An electrical instrument used for measuring electric charge.

"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…

"Pith ball pendulum or electroscope; the figures illustrate also electrical attraction and repulsion." -Hawkins, 1917

Electroscope Attraction and Repulsion

"Pith ball pendulum or electroscope; the figures illustrate also electrical attraction and repulsion."…

"Gold leaf electroscope; it consists of two strips of gold foil suspended from a brass rod within a glass jar. Used to detect the presence and sign of an electric charge." -Hawkins, 1917

Gold Leaf Electroscope

"Gold leaf electroscope; it consists of two strips of gold foil suspended from a brass rod within a…

"Faraday's ice pail experiment. An ice pail P connected with gold leaves of an electroscope C, is placed on an insulating stand S. A charged conductor K, carried by a silk thread, is lowered into the pail, and finally touches it at the bottom. While it is being lowered the leaves of the electroscope diverge farther and farther, until K is well within the pail, after which they diverge no more, even when K touches the pail or is afterwards withdrawn by the insulation thread. After withdrawal, K is found to be completely discharged." -Hawkins, 1917

Faraday's Ice Pail Experiment

"Faraday's ice pail experiment. An ice pail P connected with gold leaves of an electroscope C, is placed…

"The electrometer of Henley, sometimes called Henley's quadrant Henley electrometer, may be taken as the type of single pendulum electroscopes. It consists essentially of a pendulum A hinged to meter a verticle support C, which carries a vertical graduated semicircle B, by means of which the deviation of A from the vertical can be indicating the state of electrification of the prime conductors of electric machines. The stem is screwed into the conductor, and the divergence of the pendulum indicated roughly the charge." — Encyclopedia Britannica, 1893

Henleys Electrometer

"The electrometer of Henley, sometimes called Henley's quadrant Henley electrometer, may be taken as…

"Experiment to illustrate electrostatic induction. The leaves will diverge, ever though the charged ebonite rod does not approach to within a foot of the electroscope." -Hawkins, 1917

Electrostatic Induction

"Experiment to illustrate electrostatic induction. The leaves will diverge, ever though the charged…

"Section of Thomson's Portable Electrometer." — Encyclopedia Britannica, 1893

Portable Electrometer

"Section of Thomson's Portable Electrometer." — Encyclopedia Britannica, 1893

"Elevation and section of Thomson's Quadrant Electrometer." — Encyclopedia Britannica, 1893

Quadrant Electrometer

"Elevation and section of Thomson's Quadrant Electrometer." — Encyclopedia Britannica, 1893

"The sine electrometer of August, is a modification of the single pendulum electroscope, analogous in principle to Pouillet's sine compass. A is a pendulum suspended by two threads to secure motion in one plane; B is a ball fixd to the case, and connected with a suitable electrode." — Encyclopedia Britannica, 1893

Sine Electrometer

"The sine electrometer of August, is a modification of the single pendulum electroscope, analogous in…