Watches and Clocks

The article Watch (Vol. 28, p. 362), illustrated, by Lord Grimthorpe, the great authority on watches and clocks, and Sir H. H. Cunynghame, vice-president of the British Institute of Electrical Engineers, is full of interest. There is a very valuable historical account beginning with the invention of portable time pieces in the 15th century. The parts of a modern watch are described, with details as to the mainspring, different types of escapement, the balance-wheel and hair-spring, compensation adjustments and secondary compensation. Methods of correcting temperature errors are discussed, and a simple means for demagnetizing a watch which has been near a dynamo is given. The proper materials used for jewelled bearings are described in the articles Diamond, Corundum, etc. Lubricants (Vol. 17, p. 88) contains a valuable paragraph on the properties and preparation of the fluid oils used on the spindles of watches and clocks.

The article Clock (Vol. 6, p. 536) is by the same distinguished authorities as Watch, with an additional section on Decorative Aspects (p. 552), by James Penderel-Brodhurst. It is equivalent to 55 pages of this Guide and is fully illustrated. Among the topics considered are the earliest clocks and their gradual improvement; the essential components of a clock; the mechanics of the pendulum; methods of compensation, including the use of the new nickel-steel alloy—described in the article Invar (Vol. 14, p. 717)—the barometrical error, and methods of counteraction; suspension of pendulums; balance, anchor, dead, pinwheel, detached or free, and gravity escapements; the remontoire systems for abolishing errors in the force driving the escapement; testing of clocks; clock wheels; striking mechanism; the watchman’s clock, church and turret clocks, electrical clocks, miscellaneous clocks, including magical clocks and other curious designs. The section on Decorative Aspects tells about styles of cases and mountings, the origin and development of the “grandfather” clock, etc. In connection with long-period clocks, attention should be given to the new and ingenious, if not commercially practical, device invented by the Hon. R. J. Strutt. Electrified particles emitted by a radioactive substance separate two strips of gold leaf, and these, falling together after the charge has been conducted away upon contact with metal, are extended again, the process being constantly repeated. If some way could be found to utilize this motion to work an escapement, we should have a clock that would go on indefinitely, since 1000 years must elapse before even half the small amount of radium used has disappeared. A description of this so-called “radium” clock will be found in Perpetual Motion (Vol. 21, p. 181).

ALPHABETICAL LIST OF ARTICLES IN THE ENCYCLOPAEDIA BRITANNICA OF SPECIAL INTEREST TO MANUFACTURERS OF AND DEALERS IN JEWELRY, CLOCKS, AND WATCHES

CHAPTER XI
FOR MERCHANTS AND MANUFACTURERS OF ELECTRICAL MACHINERY AND SUPPLIES

Construction and Operation

Electrical machinery and supplies include three main groups of appliances: The apparatus by which electricity is originally generated; the apparatus by which current is transmitted and, if necessary, modified before it is used; and the infinitely various appliances for its final employment. In connection with any one of the latter, information may be needed as to its structure and its mechanical or electrochemical method of operation, or as to its uses, and in the treatment of these two aspects of a vast number of subjects the advantages of the encyclopaedic plan of the Britannica are obvious. One article will explain the method by which the same principles are applied to a number of different machines. Another article will deal with a group of appliances all used for similar purposes; and a reference to the Index of 500,000 entries (Vol. 29) will at once guide the reader who turns to the name of any electrical appliance to either kind of information he desires at the moment, whether he wants to know how the machine is made and operated, or what kind of work it does and how efficiently it does it.

The reader to whom this chapter is addressed is already familiar with the general subject of electricity, but he may at any moment desire to review or to supplement his general knowledge in connection with some new appliance which, for the first time, applies to commercial use one of the many and intricate laws of electrical vibration. The whole subject of the nature and action of electricity is outlined in the article Electricity (Vol. 9, p. 179), by Prof. J. A. Fleming, of the University of London, one of the world’s foremost authorities. In a space equivalent to hardly more than 30 pages of this Guide, the field covered in detail by many other articles is so concisely and clearly surveyed that you get a complete view of the theoretical and practical developments by which electrical science and industry have reached their present position. The same contributor then considers Electrostatics (Vol. 9, p. 240) and Electrokinetics (Vol. 9, p. 210); and, in Conduction, Electric (Vol. 6, p. 855), deals with metallic, non-metallic, dielectric and gaseous conductors. One section of this article is by Sir J. J. Thomson, winner, in 1906, of the Nobel Prize for Physics. The form in which metal is chiefly employed for the conduction of electricity is the subject of a separate article, Wire (Vol. 28, p. 738); and the articles on the individual metals deal with their electrical properties.

Batteries and Dynamos