Putnam's Elementary Science Series. MACHINE CONSTRUCTION AND DRAWING; BEING AN INTRODUCTION TO THE STUDY OF MACHINE CONSTRUCTION AND TO THE APPLICATION OF GEOMETRICAL DRAWING FOR PREFACE. THE object of this work is to supply the general student, and more especially the engineering student and workman, with an introductory book on the subject of Machine Construction and Drawing. It is unnecessary for us to speak of the importance of a knowledge of the subjects included under this title; we shall, therefore, proceed to state the order and extent of the subjects to be treated of. Machine or Mechanical Drawing will form the chief part of our work; in conjunction with this we shall consider the form and proportion of certain elementary parts of machinery. To consider the subject fully, it would be necessary to treat of subjects which are beyond the limits of the present work. A drawing being the representation of some object, in our case a machine or a part of one, it is expected that the student possesses an elementary knowledge of Practical, Plane, and Solid Geometry, since the drawing part of this book will consist of the application of the principles of those subjects to the drawing of machinery. We shall, therefore, assume that he has a knowledge of them; and if he has not, we recommend him to study them simultaneously with this work. The principal kind of projection used in mechanical drawing is that known as Orthographic or Orthogonal Projection; we shall, therefore, confine ourselves to this kind, laying down such principles as we consider of the greatest importance to the beginner, and upon which the whole will be built up in a systematic manner. We have endeavoured to arrange the subjects so that they shall form progressive exercises in drawing, and progressive examples of construction. The student, in working out the examples, should draw the figures to a larger scale than those employed for the figures in the book, except where they are drawn full size. The making of working, finished, and detail drawings will also be considered; these points and some of the various motions will be treated more fully in our Advanced Book. January, 1873. E. T. |