oints, pen with, 85.

Scale for diameter of a regular polygon, 140.
of tooth proportions, 195.
triangular, 33.

Scales, for measurement and drawing, 32.
reducing, 175.

Scratching out, 25.

Screw machine, to draw, 112, 113.
thread, United States standard, to draw, 159-160.
threads and spirals, 152-168.
threads, drawing the curves for, 159.
threads for small bolts, with the angles of the threads drawn in,
152-155.

threads of a large diameter, 156.

Section lining or cross-hatching, 77-82.

Sectional view of a section of a wheel, for showing dimensions through arms
and hub, 202.

Sector of a circle, 51.

Segment of a circle, 50.

Semicircle, 51.

Shade curve, representation of, 87.
line produced for circles, 84.

Shade line, produced in straight lines, 84.
or shadow line, 82.

Shading a Medart pulley, 280.
and coloring, points to be observed in, 278.
brush, 281.
by means of lines to distinguish round from flat surfaces, and denote
relative distances of surfaces, 85.
example in, of a Blake's patent direct acting steam pump, 284, 285.
example of, in an independent condenser, 288.
light in, 280.
simple, 277.
to show by, that the surfaces are highly polished, 282.

Shadow line, 82.
lines and line shading, 77-90.

Shaft for cam plate, 301.

Shaper link, quick return, plotting out the motion of a, 250-253.

Shoe against a cam, to find the position of the face of, 228.

Side elevation, drawing a, 106.

Sides or flats of work, to find the lengths of, 135, 136.

Slots not radiating from a centre, to draw, 131, 132.
radiating from a centre, 131.

Spiral spring, to draw, 166.

Spiral wound round a cylinder, whose end is cut off at an angle, 178.

Spirals and screw threads, 152-168.

Sponge, rubber, 26.

Spring bow pencil, for circles, 22.
pen, for circles, 22, 23.

Spring, spiral, to draw, 166.

Spur wheel teeth, how to draw, 194.

Square, a, 59, 60.
body, which measures one inch on each side, to find what it measures
across the corners, 136.

Square part, a representation of, 96.
parts, use of a cross to designate, 95, 96.
thread, to draw a, 162-164.

Steam boiler, horizontal, for stationary engine, 296.
chest and valves, 301.
chest side, and horizontal cross section of cylinder, 301.
pump, Blake's patent direct acting, 284, 285.

Steel, representation of, 277.
representation of by cross-hatching, 82.