Fortunately, the automobile is beginning to stimulate interest in practical mechanics, for no one can attempt to drive his own car, or even to obtain proper service from his chauffeur and from garage workmen, without realizing that he failed, at school, to learn some of the most useful of lessons. Before long the authorities responsible for our public schools may realize that it is absolute barbarism to neglect mechanical teaching as they do; and the new Britannica is already doing good service in stimulating public interest in the subject.
An examination of the articles mentioned in detail in the following summary, and a glance at the long list of articles at the end of the chapter, will show the comprehensiveness with which the Britannica treats all types of machinery. The materials employed are, logically, the first subjects upon which information will be desired.
Iron and Steel (Vol. 14, p. 801), by Professor H. M. Howe of Columbia University, is a mine of information about the properties and uses of the different varieties of the indispensable metal of which 50,000,000 tons per annum are employed. In the manufacture of electrical apparatus Copper (Vol. 7, p. 102) is largely employed, and for this reason alone the article has great value for the manufacturer. Almost as important is Alloys (Vol. 1, p. 704). Its chief author, Sir William Chandler Roberts-Austen, is the greatest living authority on alloys, and it is full of interesting facts about new admixtures.
The processes of Annealing, Hardening and Tempering are described in J. G. Horner’s article under that title (Vol. 2, p. 70). This authority explains clearly the difference between hardening and tempering and gives valuable advice as to the most efficient methods of hardening. Founding (Vol. 10, p. 743), also by J. G. Horner, is fully illustrated, and the question of the highest economies of machine moulding are among the practical matters considered. Forging (Vol. 10, p. 663), with 19 illustrations, discusses fullering, swaging, upsetting, bending, welding, pinching, cutting-off, and die-forging. There is also a separate article, Welding (Vol. 28), in which the section on Electric Welding is written by Elihu Thomson, who invented the process. A table of energy used in electric welding is added. See also Brazing and Soldering (Vol. 4, p. 463).
Manufacturing Methods
The designer of machinery will find much practical information in Drawing, Drawing Office Work (Vol. 8, p. 556), and Sun-Copying (Vol. 26, p. 93). It is a remarkable fact that prints identical in scale with the originals are now made up to a length of 22 feet.
Bearings (Vol. 3, p. 578), illustrated, is written by Professor Dalby of the South Kensington Central Technical College. The article Tool (Vol. 27, p. 14), by J. G. Horner, is 33 pages in length and has 79 illustrations. The whole subject is completely covered. In the section on Machine Tools are discussed turning lathes, reciprocating machines, machines with drill and bore holes, milling machines, machines for cutting the teeth of gear wheels, grinding machinery, sawing machines, shearing and punching machines, hammers and presses, portable tools, appliances, wood-working machines, and measurement. In regard to the last subject great advances have lately been made. A thousandth of an inch is now considered a coarse dimension in the machine shop, where gauges within one five-thousandth of an inch are often used. This article is an invaluable manual for the machine-shop, and supplies many hints which should be given to workmen, for, to use the author’s words, “a clumsy workman is as much out of place in a modern machine-shop as he would be in a watch-factory.” Another article useful to the mechanic is Screw (Vol. 24, p. 477), with 10 illustrations, by J. G. Horner, with a section on the Errors of Screws, by the late Henry A. Rowland, the American physicist, whose skill, shown in the construction of dividing engines of extraordinary precision and delicacy, made him famous the world over. See also Graduation (Vol. 12, p. 312).
Engines and Motors
The articles on the prime-movers are an important and noteworthy part of the new Britannica. Professor Ewing, of Cambridge University, contributes Air Engine (Vol. 1, p. 443) and Steam Engine (Vol. 25, p. 818), both fully illustrated. The latter has a most interesting preliminary historical account of engines from the aeolipile of Hero of Alexandria (about 130 B.C.) to the steam-turbine, the most modern type of all. The newest forms of internal combustion motors, Oil Engine (Vol. 20, p. 35) and Gas Engine (Vol. 11, p. 495), are described by Dugald Clerk, inventor of the Clerk cycle gas engine, and the articles are fully illustrated. Under Hydraulics (Vol. 14, p. 91) will be found complete information as to the construction of water-pressure engines, water-wheels, turbines, and also pumps. The article is written by Professor W. C. Unwin, and has been universally declared to be the best treatise on the subject that has yet appeared. There is a separate illustrated article Water-Motors (Vol. 28, p. 382), by Professor Beare of Edinburgh University. See also Windmill (Vol. 28, p. 710).
Designers and constructors of electrical machinery will be greatly interested in C. C. Hawkins’ illustrated article Dynamo (Vol. 8, p. 764), which explains fully how the dynamo is constructed and gives its history from Faraday’s discovery of the principle in 1831. Dr. Louis Bell, of the General Electric Co., writes on Motors, Electric (Vol. 18, p. 910).