marking the dimensions. The central line should first be drawn, and then the various horizontals at suitable distances ; upon these the widths of the parts should be ticked off equally on each side, and the profile of the turned parts drawn m.
The Screw Wrench (Fig. n) will be found a rather more difficult subject. The thread of the screw and the lines indicating the puriling or milling of the thumb-nut will test the student's accuracy in drawing parallel lines; the latter should be drawn closer together as they approach the edges to give the effect of roundness. Four faint lines should be drawn, two for the bottom of the thread and two for the tops or outside, and after the threads are spaced out and drawn across at a slight inclination, the intermediate parts representing stem and top of each thread should be lined in. A central line may be drawn through the handle and back bar. and the edges set off equally on each side and the jaws drawn perpendicular to it.
The UseofSquared Paper, or the ruling of linesforming squares upon the drawing, is a device that will be found of assistance in making more elaborate freehand drawings, such as the masonry details shown on page 133 opposite; also for enlarging or diminishing a drawing proportionately. In the drawing office, tracing paper with lines ruled in squares of suitable dimensions is generally used. A sheet is secured over the drawing to be copied, the lines that are printed on it breaking the drawing up :nto a number of parts with location points, where the lines ntersect the outlines of the drawing. It the drawing is to be copied to the same size, a scries of squares of similar size are ruled iri pencil over the drawing paper, and the various points ticked off upon it just as they occur on the original Each iine is numbered similarly on both sheets to assist in identifying the points, and, when a sufficient number are located, the outline can be completed by freehand.
When it is desired to enlarge or reduce the copy, appropriate size squares are drawn 011 the sheet to the desired
proportion. Tlius in the drawing, page 135, the carved spandrel forming parr of the window head, page 133, is enlarged to treble the size of the original, and if it were desired to reduce it to, say, one-third the size, the squares would need to be drawn one-third the size of the squares thai art1 drawn upon the original, or upon the tracing paper used. This paper is procurable at the drawing instrument shops, under the name of sectional drawing and tracing paper, and it can be obtained ruled in squares from TV in. to 12 in. The smaller rulings on drawing paper are also used for making drawings to scale without the necessity of using " scales"—e.g. if the paper is ruled in -J- in. squares a drawing may be made upon it to scale of a in. to one foot, each square representing one foot, and a line, say, extending over six squares would represent 6 ft. and so 011.
The Scries of Hinges shown on page 137 will afford good exercise in freehand drawing. All the necessary instructions for copying are embodied in the previous notes, but a brief description of the various types illustrated may be useful.
The Butt Hinge. Fig. 1, page 137, is probably the com monest; it is made in various sizes from | in. to 6 in long, and is used for a great variety of purposes, but invariably upon the - edges of the parts to be hinged; thus the two " edges " of the hinged surfaces come together when closed and are said to " abut " squarely to each other, hence the generic, name of the hinge, distinguishing it from the types that are fixed upon the surface or face of the hinged parts.
The flanges or wings of the butt are always sunk in flush, and the joint or " knuckle " usually projects, that the door, etc., may swing clear of adjacent projections, but in some particular cases the knuckle is sunk flush with the surface of a bead on the edge of the frame, the edge of the door or shutter working closely around the bead. This method is termed by joiners " close-joint " hanging. The details of both methods are fully described in the author's work on
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