Whittaker's Mechanical Engineer's Pocket-Book

Abstract

A GOOD pocket-book is a necessity to the engineer; it supplies him with reference tables and constants for facilitating calculations, and also the experience of other engineers in a condensed and handy form for use. One feature of this work is that a rather larger share than usual is given to hydraulics and hydraulic machinery, and also to mining plant. In the formula on p. 3, for the discharge over weirs, a too small coefficient of discharge (apparently 0˙45 only) has been adopted; there is also a misprint in the first line of the second column on p. 7, it should be 8˙025. In the formula on p. 55, for friction of the leather collars of rams, it is not stated in what units the answer is obtained; presumably it is in pounds. The one section which is very disappointing is that devoted to gas engines; only three pages are given to them, and one of these is filled with a useless description of the two original types—the Lenoir and Otto and Langen, both of course interesting in an historical account of the origin of the gas engine, but not of the slightest value or claim to notice in a pocket-book: in future editions it is to be hoped more attention will be given to this section, and that the page mentioned will be cut out. The author would have done well to make use of the recent determination of the mechanical equivalent of heat; most engineers are now adopting 778 as the figure. On p. 93 occurs an awkward misprint in the formula for mean pressure of steam; the letter in the denominator should be R, and not P, as printed. The rules given for the cooling surface of surface condensers, on p. 113, must apply only to single-cylinder engines; at any rate, they give areas greater than usually adopted in the best modern practice for triple compound plants. The sections devoted to pipes and gearing are admirable, and there are many most useful tables; the last fifty or sixty pages contain a valuable collection of tables of weights of various sections of iron and steel, areas of circles, cubes, square roots, &c. We have pointed out a few blemishes, but the book as a whole is very free from slips or errors, and will be, no doubt, of service to many engineers, draughtsmen, and works-managers.

Whittaker's Mechanical Engineer's Pocket-Book.

By Philip R. Björling. Pp. 377 + viii. (London: Whittaker and Co., 1898.)