_a._ The steam cylinders and water cylinders must be connected by such
a form of yoke as requires no packing, a metal to metal joint at this
connection being considered necessary. The piston-rod stuffing box
heads should concentrically fit the counter-bore of the yoke.
If packing is put into these joints, there is a chance of the steam
and water ends getting out of alignment and leaking at the joint
between cylinders and yoke.