plate at each end of the paddle shafts
tightened with a key, to prevent end play when the vessel rolls, but the
arrangement is precarious and insufficient. Messrs. Maudslay make their
paddle shaft bearings with very large fillets in the corner, with the view
of diminishing the evil; but it would be preferable to make the bearings of
the crank shafts spheroidal; and, indeed, it would probably be an
improvement if most of the bearings about the engine were to be made in the
same fashion. The loose end of the crank pin should be made not spheroidal,
but consisting of a portion of a sphere; and a brass bush might then be
fitted into the crank eye, that would completely encase the ball of the
pin, and yet permit the outer end of the paddle shaft to fall without
straining the pin, the bush being at the same time susceptible of a slight
end motion. The paddle shaft, where it passes through the vessel's side, is
usually surrounded by a lead stuffing box, which will yield if the end of
the shaft falls; this stuffing box prevents leakage into the ship from the
paddle wheels: but it is expedient, as a further precaution, to have a
small tank on the ship's side immediately beneath the stuffing box, with a
pipe leading down to the bilge to catch and conduct away any water that may
enter around the shaft.

487. _Q._--How is the outer bearing of the paddle wheels supplied with
tallow?

_A._--The bearing at the outer end of the paddle shaft is sometimes
supplied with tallow, forced into a hole in the plummer block cover, as in
the case of water wheels; but for vessels intended to perform long voyages,
it is preferable to have a pipe leading down to the oil cup above the
journal from the top of the paddle box, through which pipe oil may at any
time be supplied.

488. _Q._--Will you explain the method of putting engines into a steam
vessel?

_A._--As an illustration of this operation it may be advisable to take the
case of a side lever engine, and the method of proceeding is as follows:--
First measure across from the inside of paddle bearers to the centre of the
ship, to make sure that the central line, running in a fore and aft
direction on the deck or beams, usually drawn by the carpenter, is really
in the centre. Stretch a line across between the paddle bearers in the
direction of the shaft; to this line, in the centre of the ship where the
fore and aft mark has been made, apply a square with arms six or eight feet
long, and brin