Electricity
Electricity names 2 different subjects across the 6 encyclopedias on this shelf. Each is set out below.
Electricity a powerful physical agent which makes its resistance manifest
Collier's New Encyclopedia (1921)
a powerful physical agent which makes its resistance manifest by attractions and repulsions, by producing light and heat, commotions, chemical decompositions and other phenomena. About 600 b. c. Thales dicovered that when amber was rubbed with silk it became capable of attracting light bodies. The ancients seem to have known no more than this regarding electricity; nor for the first 16 centuries of the Christian era was much addition made to the solitary known fact in electricity. In 1600, Gilbert, who was surgeon to Queen Elizabeth and to James I., published a book, "De Magnete," in which for the first time the word "electric" was used in connection with science. He He regarded magnetism died in 1603. and electricity as two emanations of one fundamental force. He showed that not merely amber, but sulphur, glass, etc., are electrics. Otto Guericke, of Magdeburg, discovered that there was a repulsive as well as an attractive force in electricity, and about 1647 constructed the first electrical machine. Newton, in 1675, observed signs of electrical excitement in a rubbed plate of glass. Hawkesbee, who wrote in 1709, also observed similar phenomena; and Dufay, in the "Memoirs of the French Academy," between 1733 and 1737, generalized so far as to lay down the principle that electrified bodies attract all those which are not so, and repel them as soon as they have become electric by the vicinity or contact of the electric body. Dufay also discovered that a body electrified by contact with a resinous substance repelled another electrified in a similar way, and attracted one which had been electrified by contact with glass. He thence concluded that the electricity derived from those two sources was of different kinds, and applied the names vitreous and resinous to them. Franklin attributed this difference to an excess or deficiency of the electric fluid, the former condition existing in electrified glass and the latter in resins. Otto Guericke had discovered that his sulphur globe, when rubbed in a dark place, emitted faint flashes of light, and shortly afterward it was noticed that a similar phenomenon occurred at the surface of the mercury when the barometer was shaken a fact which one of the celebrated mathematicians, Bernouilli, attempted to explain on the Cartesian system, but which was afterward correctly attributed by Hawkesbee to electric charges. Wall, in 1708, observed the sparks produced from amber, and Hawkesbee noticed the sparks and "snapping" under various modifications. Dufay and Abbé Nollet were the first to draw sparks from the human body, an experiment which attracted great attention, and became a species of fashionable diversion at the time. The discovery of the Leyden jar is attributed to Cunæus of Leyden, in 1746, who, while handling a vessel containing water in communication with an electrical machine, was surprised at receiving a severe shock. A similar event had happened the year previous to Von Kleinst, a German prelate. In the 18th century the names of the principal contributors to the advancement of electrical science are Newton, Hawkesbee, Dufay, Guericke, Cunæus of Leyden (to whom we owe the Leyden jar), and Franklin, who, 1747, pointed out the circumstances on which the action of the Leyden jar depends. Monnier the younger discovered that the electricity which bodies can receive depends on their surface rather than their mass, and Franklin soon found that "the whole force of the bottle and power of giving a shock is in the glass itself"; he further, in 1750, suggested that electricity and lightning were identical in their nature, and in 1752 demonstrated this fact by means of his kite and key. About the same time D'Alibard and others in France erected a pointed rod 40 feet high at Marli, for the purpose of verifying Franklin's theory, which was found to give sparks on the passage of a thunder cloud. Similar experiments were repeated throughout Europe, and in 1753 Richman was instantly killed at St. Petersburg by a discharge from a rod of this kind. The more important discoveries since those days relate rather to electricity produced by voltaic or magnetic action. In the later history of electricity no name is greater than that of Michael Faraday, who was born in London in 1794, was appointed by Sir Humphry Davy assistant in the laboratory of the Royal Institution in March, 1813, and in 1831 commenced the publication of a series of splendid discoveries in electricity. The past history of electricity centers round the frictional machine and the voltaic battery. The first-named is now only of of experimental expe interest, and the second, if we except its use in signaling (telegraphy and telephony), is quickly being supplanted by the more economical and vastly more powerful dynamomachine. To this contrivance, in its various forms, as designed by different makers, and in less degree to the secondary battery (now quite in its infancy), electricians look for the advancement of their science. The fact that the Gramme and similar machines are reversible is considered to be one of the most important discoveries of the century. By reversible is meant its power to act as a motor when coupled up with a distant machine, under which circumstances its armature rapidly revolves in the reverse direction to what it would do if used directly-as in the production of the electric light. By such means the electrical transmission of power from place to place has become possible. Important advances in the knowledge of the connection between electricity and matter have in recent years been made through the observation of the ionization of gases. The principal researches along this line were made by Professor J. J. Thomson, at the Cavendish Laboratory, at Cambridge, England. All gases can be made conductors of electricity when the molecules of the gas have been broken into parts, that is, ionized. Among the methods for ionizing gas are (1) application of high temperature; ature; (2) the passage of a spark in the neighborhood; (3) exposure to Röntgen rays or to rays from a radioactive substance such as uranium; (4) exposure to "cathod" rays; (5) exposure to "ultraviolet" light. It has been established that the negative ions of all gases, however they may be produced, are identical. The practical application of electricity to industry and to domestic uses has been one of the great developments of the last generation. The development of the automobile has called for storage batteries of high power and electricity and has also been employed as a motor power for motor vehicles. See MOTOR VEHICLE. In transportation, the use of electricity has come to be common, especially in suburban lines of railroad where a long haul is not required. For domestic use electricity is employed not only for lighting and heating but for devices including vacuum cleaners, electric irons, washing machines, and countless other devices. For a discussion of the different phases of electricity and its use, see STORAGE BATTERIES, ELECTRICAL MACHINE, TRANS- MISSION OF ELECTRIC POWER, DYNAMO, CTRICITY, ANIMAL
Electricity ANIMAL, the branch of electric science to which an
Collier's New Encyclopedia (1921)
ANIMAL, the branch of electric science to which an experiment by Galvani gave birth. His wife, who was making soup from frogs, happened to put them, after being skinned, in proximity to a charged electrical machine belonging to her husband. On touching them with a scalpel their legs became greatly convulsed. Galvani on his return was told what had occurred, and repeated the experiment on several occasions. He united the lumbar nerves of dead frog with its crural muscles by a metallic circuit. He came to the erroneous conclusion that animal electricity existed in the nerves and muscles of frogs, etc. In this explanation Galvani ignored the metallic connecting wire. His contemporary, Volta, gave attention to this, and found that the contraction of the limbs is more energetic when the connecting arc is made of two metals instead of one. He therefore inferred that the metals took the active part in producing the contraction, and the disengagement of electricity was due to their contact, and that the animal parts constituted only a conductor, and at the same time a very sensitive' electroscope. In 1793 he published these views, and in 1800 first described and constructed what has since been called after him the voltaic pile. Febroni observing that the disks of zinc in the pile became oxidized in contact with the acidulated water, considered, as did Wollaston and Davy, that the oxidation was the chief cause why electricity was disengaged. Now voltaic piles have nearly given place to voltaic or galvanic batteries of which there are many varieties. ELECTRICITY IN MEDICINE. The use of electricity in treatment of human diseases dates back to the 18th century, when the electric spark and frictional Franklin electricity were so applied. Fra was the first to use shocks from Leyden jars for the treatment of paralysis. As far back as 1775 the effect of static electricity on the human system was well known, and was dealt with to considerable length in the writings of Tiberius Cavallo in 1777. The discovery of voltaic, or galvanic, electricity in 1800, and of faradic electricity during the past century were further steps in electro-therapeutics, since they allowed treatment than was possible of a gentler trea by means of the Leyden jars. For a long time static electricity was not in ase, but more recently there has been a return to that method because of modern methods of application. The application of electricity to the human body for curative purposes may be divided into three forms; static, galvanic, and faradic. The first form is produced from the ordinary frictional machine, in which glass plates are revolved against chamois, rubber or horsehair brushes, the current being received in Leyden jars. Galvanic electricity is set in motion by the voltaic battery. And faradism, or faradic electricity, is produced by induced, or interrupted, currents, generated by magneto-electric or electro-magnetic induction coil machines. The first form, static electricity, produces many effects on the human body. It has been long known that the body loses weight through its application, and that it causes the temperature either to rise or fall, due to increased functional rise It sets free the potential activity. energy cells, causes contraction of protoplasm, excites nerve fibers, nerve cells and nerve centers, and stimulates nutrition. It is, therefore, effective in the treatment of lumbago, spastic paralysis, locomotor ataxia, chronic and muscular rheumatism, neuritis, progressive muscular atrophy, insomnia, congestion of the liver, and sciatica. It also serves to nervous headaches, hysteria, control neurasthenia, and is valuable also as a general tonic. It has also been effectively used in reducing sprains. The only danger of its use, in unpracticed hands, lies in the liability of a reduction of the blood pressure, which in certain cases may produce bad effects. For this reason care should be taken to avoid the numerous quacks and charlatans who advertise widely the use of electricity for curative purposes. For this reason it is advocated the use of electricity be restricted to the legitimate medical profession. Galvanic treatment is produced by passing a voltaic current from a battery of many elements through the living body, which causes a shock, or contraction, of the muscular system, succeeded with a distinct interval by a momentary sensation or flow of heat due to the electric current. During the continued passage of the current, slight tingling sensations and a raising of the temperature are felt, especially ly in those parts in contact with the electrodes, which become painful and congested. On opening the circuit, the depolarization of the tissues which follows is accompanied by a second shock and a glow of heat, which are powerful in proportion to the length of time the circuit has been closed. The contraction of the muscles is in proportion to the intensity, rather than to the amount of the electricity which flows through the body. The use of this 32-Vol. III-Cyc method of application is to exercise atrophied muscles and secure their nutrition. In surgery the electrolytic action of the galvanic current destroys tumors and abnormal growths in the nasal cavity. The galvanic current is also used in heating a cautery for searing a surface to secure a cicatrix. The use of faradic electricity is usually for its tonic effect. The continued passage of the interrupted currents acts chiefly as a mechanical stimulant, first exciting, and after a time depressing the vitality of the parts in the circuit. Vibrations produced by purely mechanical means, without the use of electricity, may be made to cause very similar effects. Faradization is especially applicable to those diseases in which a deficiency of functional energy is involved, as in mild cases of spinal and peripheral paralysis. Changes of circulation or of the molecular state may be excited in the central organs by reflex irritation. It has also been used with good effect in the treatment of gout, rheumatism, widespread ecezma, and constipation, when due to indigestion. Galvanic electricity, however, will also produce all the effects due to the faradic current, but to a very much higher degree. ELECTRIC LAMP. See ELECTRIC LIGHT.
What Has Changed in the Last Century
Collier's in 1921 still defined electricity as "a powerful physical agent" and told its story through amber, the Leyden jar and Franklin's kite, treating the frictional machine as a museum piece and the dynamo as the future. The talk of an "electric fluid" and of vitreous versus resinous kinds has been fully replaced by the electron, identified by J. J. Thomson in 1897 and now understood to carry a fixed quantum of charge; the modern theory of how charges and light interact, quantum electrodynamics, was worked out in the 1940s by Feynman, Schwinger and Tomonaga, who shared the 1965 Nobel Prize for it. The entry's forecast that electrical transmission of power "from place to place has become possible" proved an understatement: continent-spanning grids now reach roughly nine-tenths of the world's people. The secondary battery Collier's called "quite in its infancy" grew into the lithium-ion cell of 1991, which now moves cars.
Written for this edition, 2026.