ndrical and free from any dents. Mandrel-drawn brass tubing,
1/16-inch thick, may be selected. If you cannot get this turned off at the
ends in a lathe, mark the lines round it for working to with the aid of a
perfectly straight edged strip of paper, 2-13/16 inches wide, rolled twice
round the tube. The coils must lie exactly under one another. Make plain
scratches at each end of the paper with a sharp steel point. Cut off at a
distance of 1/16-inch from the lines, and work up to the lines with a file,
finishing by rubbing the ends on a piece of emery cloth resting on a hard,
true surface.

[Illustration: FIG. 56.-Cylinder standard before being bent.]

A square-cornered notch 1/8 inch deep and 7/8 inch wide must now be cut in
each end of the barrel, the two notches being exactly in line with one
another. These are to admit steam from the steam ways into the cylinder.

Cylinder Standards.-Use 5/64 or 3/32 inch brass plate for these. Two pieces
of the dimensions shown in Fig. 56 are needed. Scratch a line exactly down
the middle of each, and a cross line 1/2 inch from one end. The other end
should be marked, cut, and filed to a semicircle. Drill three 3/16-inch
holes in the turnover for the holding-down screws. The two standards should
now be soldered temporarily together at the round ends and trued up to
match each other exactly. Place them in the vice with the bending lines
exactly level with the jaws, split the turnovers apart, and hammer them
over at right angles to the main parts. Whether this has been done
correctly may be tested by placing the standards on a flat surface. Take
the standards apart, and scratch a cross line on each 1-5/8 inch from the
lower surface of the foot on the side away from the foot. Make a punch mark
where the line crosses the vertical line previously drawn, and with this as
centre describe a circle of the diameter of the outside of the barrel. Cut
out the inside and file carefully up to the circle, stopping when the
barrel makes a tight fit. On the inside of the hole file a nick 1/8 inch
deep, as shown in Fig. 56. Remember that this nick must be on the left of
one standard and on the right of the other, so that they shall pair off
properly.

Standards and barrel must now be cleaned for soldering. Screw one standard
down to a wood base; slip one end of the barrel into it; pass the other
standard over the other end of the barrel, and adjust everything so that
the barrel ends are flush with