province to design improvements, to furnish sketches and to make finished drawings; to calculate strains, strength, power, motion, weight, friction and durability. All this and much more is the professional draughtsman's work. In "directory" classification, he who accomplishes such comprehensive results as above described is termed Draughtsman," but the word has as wide a meaning as "Engineer," which takes in civil, mechanical, naval, sanitary, steam and other engineering specialists. So, in drafting, it includes the office boy employed in making blue prints, it embraces the copyists, tracers and assistants, as well as the head draughtsman and chief engineer. Consequently the range is wide, and the line hard to draw between draughtsmen who work with their hands, and those who work with their brains. It may be added that the best men are too frequently undervalued, owing to the unavoidable difficulty in distinguishing the difference in true worth, between the two widely separated classes. It may be remarked that they only draw well who draw intelligently; aptness in this, as in many other virtues, is a matter of slow growth, "here a line and there a line"-it's the proper direction, not the rate of progress, that counts in the end. There are several methods of drawing-1, Free-hand; 2, Instrumental; 3, Geometrical; 4. Perspective. In the first the work, also termed sketching, is executed by pencil, pen, crayon, or even paint-brush; in the second the result is attained by the use of rule, tee-square, drawing pen, etc.; this method is also denominated mechanical drawing, and suggests the title of this volume. The great usefulness, not to say necessity, of readiness in executing accurately, drawings "to scale," is emphasized by the fact that now, more than ever, is all machinery designed, and it may almost be said, is "built," in the draughting room-this is a valuable hint relating to “reading" drawings. It is wise, as well as easy, to begin at the beginning of things; thus, it is altogether the good part to mount a ladder by the first and second rounds rather than to attempt it by taking the third, sixth, ninth, etc.— especially are first and second rounds the very best to start upon; "Chalk-work," is the first subject introduced, next, that of "Free-hand." These are the first steps leading upward in this most agreeable attainment-skill in illustrating and designing of objects, tools, and utilities. A single word of advice before introducing the elementary work connected with mechanical drawing: if the student should experience difficulty in mastering the diagrams and curves abounding in this book, let him consult an experienced draughtsman or teacher, who, by a few strokes of a lead pencil, can easily make them plain ; that knowledge--which cannot be printed or self-taught-termed the Craftsman's Art, is communicated largely by personal telling and showing, from man to man; in drawing, this help should be thankfully availed of, when necessity arises. NOTE-Sketching is often in demand because there is no time for finished or careful drawings, and the one who can draw a few lines in a moment to let a sudden necessity be known, is the man of the hour. All candidates for First Class Engineer's Certificates in marine service in the navy have to undergo an examination in rough drawing; this is intended not so much as a proof of the applicant possessing the capability of a draughtsman, but in the event of any injury to the engines in his charge, so that he may be able to send to his Superintendent a rough drawing of the particular part, properly dimensioned. so that it could be worked from, and time saved on the arrival of the ship at the port where the repairs are to be done. |
