hole at the centre.
The wheel disc is then screwed to a perfectly flat board or plate, the
wooden disc being used as a spacer between them.

Slip a blade into place on the disc, easing the central slit, if necessary,
to allow the near edge to lie in contact with the board--that is parallel
to the disc. Solder on the blade, using the minimum of solder needed to
make a good joint. When all the blades are fixed, you will have a wheel
with the blades quite true on one side. It is, therefore, important to
consider, before commencing work, in which direction the concave side of
the blades should be, so that when the wheel is mounted it shall face the
nozzle.

To make this point clear: the direction of the nozzle having been decided,
the buckets on the trued side must in turn present their concave sides to
the nozzle. In Fig. 70 the nozzle points downwards, and the left side of
the wheel has to be trued. Therefore B1 has its convex, B2 its concave,
side facing the reader, as it were.

The Nozzle is a 1-1/2 inch piece of brass bar. Drill a 1/20-inch hole
through the centre. On the outside end, enlarge this hole to 1/8 inch to a
depth of 1/8 inch. The nozzle end is bevelled off to an angle of 20
degrees, and a broach is inserted to give the steam port a conical section,
as shown in Fig. 72, so that the steam may expand and gain velocity as it
approaches the blades. Care must be taken not to allow the broach to enter
far enough to enlarge the throat of the nozzle to more than 1/20 inch.

[Illustration: FIG. 72.--Nozzle of turbine, showing its position
relatively to buckets.]

Fixing the Nozzle.--The centre of the nozzle discharge opening is
1-13/16-inches from the centre of the wheel. The nozzle must make an angle
of 20 degrees with the side of the casing, through which it projects far
enough to all but touch the nearer edges of the vanes. (Fig. 72.) The wheel
can then be adjusted, by means of the spindle nuts, to the nozzle more
conveniently than the nozzle to the wheel. To get the hole in the casing
correctly situated and sloped, begin by boring a hole straight through, 1/4
inch away laterally from where the steam discharge hole will be, centre to
centre, and then work the walls of the hole to the proper angle with a
circular file of the same diameter as the nozzle piece, which is then
sweated in with solder. It is, of course, an easy matter to fix the nozzle
at the proper angle to a thin plate, which can be screwed on to t