(b) Conduction of Heat (Vol. 6, p. 890); Radiation, Theory of (Vol. 22, p. 785); Radiometer (Vol. 22, p. 806).
(c) Fusion (Vol. 11, p. 369); Vaporization (Vol. 27, p. 897); Condensation of Gases (Vol. 6, p. 844); Liquid Gases (Vol. 16, p. 744); Thermoelectricity (Vol. 26, p. 814).
(V) Electricity and Magnetism
Historical
We are so accustomed to think of electricity as the peculiar possession of our own age (the first crude attempts at an electric light were only two score years ago) that we are apt to forget that the first experiments in the science were made at least 2500 years ago. The first effort to place it on a true experimental and inductive basis dates back more than three centuries to the publication of the researches of William Gilbert (see Vol. 12, p. 9), the most distinguished man of science of his time, whom Queen Elizabeth appointed her private physician at the “usual” salary of £100. A hundred years later, Volta (Vol. 28, p. 198), who might be called the patron saint of electricity, produced the first electric current with the pile which bears his name. Meanwhile Benjamin Franklin (Vol. 11, p. 30) had been experimenting with his famous kite, and Cavendish (Vol. 5, p. 580) and Coulomb (Vol. 7, p. 508) had been paving the way for the startling developments which resulted from Volta’s invention. In the 19th century Faraday (Vol. 10, p. 173), Ampère (Vol. 1, p. 878), Ohm (Vol. 20, p. 34), Lord Kelvin (Vol. 15, p. 721), James Clerk Maxwell (Vol. 17, p. 929) and other brilliant investigators in rapid succession developed the field, until the science and application of electricity have attained a position absolutely dominating our daily life.
Analysis of the Subject
The section of the Britannica treating this great subject is therefore one of the most important in the whole work, and it was in the fullest recognition of the fact that the editor asked Prof. J. A. Fleming, of the University of London, famous for his original work in both the mathematical and the experimental branches of the science, to organize the sections for the new edition. The ground is generally covered in the four articles, on electricity, electrostatics, electrokinetics, and electromagnetism, all contributed by Prof. Fleming himself. The article Electricity (Vol. 9, p. 179) is the key article to the subject, and should be read first. The two great branches of electrical theory then follow: (a) Electrostatics (Vol. 9, p. 240), in connection with which the article Electrical Machine (Vol. 9, p. 176) should also be studied, with reference to Electroscope (Vol. 9, p. 239) and Electrophorus (Vol. 9, p. 237). (b) Electrokinetics (Vol. 9, p. 210) and, supplementing it, Conduction, Electric (Vol. 6, p. 855). The latter is divided into three parts: (i.) Conduction in Solids, by Prof. Fleming; (ii.) Conduction in Liquids by W. C. D. Whetham; (iii.) Conduction in Gases, by Sir J. J. Thomson. In connection with (ii.) should be read Electrolysis (Vol. 9, p. 217), by W. C. D. Whetham, and with (iii.) Röntgen Rays (Vol. 23, p. 694) and Vacuum Tube (Vol. 27, p. 834), both by Sir J. J. Thomson, whose article Electric Waves (Vol. 9, p. 203) is of fundamental importance. The general principles of electrical engineering are set out in the article Electric Supply (Vol. 9, p. 193) with reference to Dynamo (Vol. 8, p. 764); Motors, Electric (Vol. 18, p. 910); Transformers (Vol. 27, p. 173); Accumulator (Vol. 1, p. 126); Power Transmission, Electric (Vol. 22, p. 233); Traction, Electric Traction (Vol. 27, p. 120); Lighting, Electric (Vol. 16, p. 659); see also Electrochemistry (Vol. 9, p. 208) and Electrometallurgy (Vol. 9, p. 232); Telegraph (Vol. 26, p. 510); Telephone (Vol. 26, p. 547).
A bridge to Magnetism (Vol. 17, p. 321), an article by Shelford Bidwell, former president of the Physical Society, is the article Electromagnetism (Vol. 9, p. 226), by Prof. Fleming. This article leads also to the study of manifestations in nature of electricity and magnetism: see the articles Atmospheric Electricity (Vol. 2, p. 860); Aurora Polaris (Vol. 2, p. 927); Earth Currents (Vol. 8, p. 813); and Magnetism, Terrestrial (Vol. 17, p. 353); and to the applications of its principles in the Compass (Vol. 6, p. 804).
An alphabetical list of the articles in the Britannica on the subjects treated in this chapter is given below. The biographies of distinguished physicists, included in the list, are valuable as containing accounts of their contributions to science, and are full of human interest.