Now assemble the case, taking care that the edge of the ring corresponds exactly with the circles marked on the discs, and clean the metal round the bearing holes and the bearings themselves.  The last are then placed in position, with the lubricating holes pointing upwards towards the guide marks on the discs.  Push the spindle rod through the bearings, which must be adjusted until the rod can be revolved easily with the fingers.  Then solder in the bearing with a “Tinol” lamp.

The Wheel.—­Anneal this well by heating to a dull red and plunging it in cold water.  Mark a circle of 1-1/4-inch radius, and draw radial lines 1/4 inch apart at the circumference from this circle to the edge.  Cut out along the lines, and twist the vanes to make an angle of about 60 degree with the central part, and bend the ends slightly backward away from the direction in which the rotor will revolve. (The directions given on p. 189 for making a steam top wheel can be applied here.)

Bore a hole in the centre to make a tight fit with the spindle, and place the rotor in position, with piece B in contact on the C side.  Get everything square (rotation will betray a bad wobble), and solder the three parts together with the blow-lamp.

Mount the rotor squarely by the spindle points between two pieces of wood held lightly in the vice, and, with the aid of a gauge fixed to the piece nearest the wheel, true up the line of the vanes. (Lathe useful here.)

The Steam Pipe is 15 inches (or more) of 5/16-inch copper tubing, well annealed.  To assist the bending of it into a ring one needs some circular object of the same diameter as the interior diameter of the ring round which to curve it.  I procured a tooth-powder box of the right size, and nailed it firmly to a piece of board.  Then I bevelled off the end of the pipe to the approximately correct angle, laid it against the box, and drove in a nail to keep it tight up.  Bending was then an easy matter, a nail driven in here and there holding the pipe until the ring was complete.  I then soldered the end to the standing part, and detached the ring for flattening on one side with a file and emery cloth.  This done, I bored a hole through the tube at F to open up the blind end of the ring.

Attaching the ring to disc D is effected as follows:—­Tin the contact faces of the ring and disc pretty heavily with solder, after making poppet marks round the guide circles so that they may not be lost under the solder.  The ring must be pressed tightly against its seat while heating is done with the lamp.  An extra pair of hands makes things easier at this point.  Be careful not to unsolder the spindle bearing, a thing which cannot happen if the bearing is kept cool by an occasional drop or two of water.  A little extra solder should be applied round the points where the ports will be.

The Steam Ports.—­These are drilled (with a 1/32-inch twist drill), at an angle of about 30 degrees to the plate, along the circle already scribed.  If you have any doubt as to your boiler’s capacity, begin with one hole only, and add a second if you think it advisable.  As already remarked, pressure must not be sacrificed to steam flow.