sks.

(3.) Fit a steam gauge, so that you may know what is happening.

(4.) Test your boiler under steam, and don't work it at more than half the
pressure to which it has been tested. (See p. 220.)

In the present chapter we will assume that the barrels of all the boilers
described are made out of solid-drawn seamless copper tubing, which can be
bought in all diameters up to 6 inches, and of any one of several
thicknesses. Brass tubing is more easily soldered, but not so good to
braze, and generally not so strong as copper, other things being equal.
Solid-drawn tubing is more expensive than welded tubing or an equivalent
amount of sheet metal, but is considerably stronger than the best riveted
tube.

Boiler ends may be purchased ready turned to size. Get stampings rather
than castings, as the first are more homogeneous, and therefore can be
somewhat lighter.

Flanging Boiler Ends.--To make a good job, a plate for an end should be
screwed to a circular block of hard wood (oak or boxwood), having an
outside diameter less than the inside diameter of the boiler barrel by
twice the thickness of the metal of the end, and a rounded-off edge. The
plate must be annealed by being heated to a dull red and dipped in cold
water. The process must be repeated should the hammering make the copper
stubborn.

Stays should be used liberally, and be screwed and nutted at the ends. As
the cutting of the screw thread reduces the effective diameter, the
strength of a stay is only that of the section at the bottom of the
threads.

Riveting.--Though stays will prevent the ends of the boiler blowing off,
it is very advisable to rivet them through the flanges to the ends of the
barrel, as this gives mutual support independently of soldering or brazing.
Proper boiler rivets should be procured, and annealed before use. Make the
rivet holes a good fit, and drill the two parts to be held together in one
operation, to ensure the holes being in line. Rivets will not close
properly if too long. Dies for closing the rivet heads may be bought for a
few pence.

Soldering, etc.--Joints not exposed directly to the furnace flames may be
soldered with a solder melting not below 350 degrees Fahr. Surfaces to be
riveted together should be "tinned" before riveting, to ensure the solder
getting a good hold afterwards. The solder should be sweated right through
the joint with a blow-lamp to make a satisfactory job.

All joints exposed to the flames shoul