Abstract
THIS work consists of three separate directories, separately paged, but bound up together; the first, of 228 pages, relates to British trades and professions connected with electricity; the second, of 273 pages, is devoted to similar matters from America; whilst the third is Continental. Of the last, 71 pages are French and Belgian, 12 German, and 3 relate to other countries, chiefly Russia. This arrangement, though convenient probably to the compilers, strikes us as being bad for many purposes. The American and French sections are particularly full of information. The British section opens with remarks on the progress made in electrical business during the past year, after which come various tables and formulæ. These are by no means satisfactory. In the formulæ for dimensions of units, many of the numbers which should have been printed as powers are given as simple multipliers. Though the table begins with C.G.S. units, and professes to describe those accepted by the British Association and the International Congress of 1881, the ohm is given as equal to 107 absolute units and the volt as 105, whereas the figures should respectively be 109 and 108. All this is very misleading. So also is the following statement:—“Calling gravitation the natural unit of force, the absolute unit of force will be 1/9.81th part of it.” This statement ushers in the following definition:—“Unit of Mechanical Effect is the unit of force carried up through one centimetre, or 1/9.81 raised one centimetre.” Is it possible that this chapter on formulas has been translated literally from the pages of some French writer who was in the habit of using a mixed metre-gramme-second system instead of either the centimetre-gramme-second or the metre-kilogramme-second system? With the exception of the scientific part, the editing appears to have been carefully and soundly done, and the commercial information is very extensive.
Berfy's Electrical Directory.
Third Edition. (London and New York, 1884.)
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Our Book Shelf . Nature 29, 524 (1884). https://doi.org/10.1038/029524a0
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DOI: https://doi.org/10.1038/029524a0