Machine Drawing

Abstract

IN this text-book the author presents a course of instruction which he considers suitable for students attending elementary drawing classes who are unable to spare more than one evening per week, and whose technical training is thus confined to the one subject of machine drawing. Three dozen plates are given, affording a choice of examples to be copied to scale from the dimensions figured, some of which are proportional dimensions covering a range of sizes. Accompanying the plates are descriptive accounts of the construction and uses of the machine parts drawn, with sets of questions founded thereon. At intervals, where space is available, formulae and physical data are introduced and used in making calculations illustrating machine design. This crude attempt to teach applied mechanics along with elementary machine drawing seems to us a mistake, as, in the absence of a knowledge of mechanical principles, such formulae as are given become mere rules of thumb, and any attempt to apply them independently cannot fail to be disastrous, as, for instance, in the author's method of estimating the limiting speed of a fly.-wheel on p. 42. The time wasted on these premature calculations might very profitably be spent with rule, callipers, and squared paper, in measuring and makings careful and complete dimensioned sketches of actual machine parts, and so cultivating the habit of closely and accurately observing constructional details.

Machine Drawing.

By Alfred P. Hill. Pp. 83. (London: P. S. King and Son, 1904.) Price 2s. 6d. net.