dle arms to the outer ring by means of
bolts; but unless very carefully fitted, those bolts after a time become
slack sideways, and a constant working of the parts of the wheel goes on in
consequence. Sometimes the part of the other ring opposite the arm is
formed into a mortise, and the arms are wedged tight in these holes by
wedges driven in on each side; but the plan is an expensive one, and not
satisfactory, as the wedges work loose even though riveted over at the
point. The best mode of making a secure attachment of the arms to the ring,
consists in making the arms with long T heads, and riveting the cross piece
to the outer ring with a number of rivets, not of the largest size, which
would weaken the outer ring too much. The best way of securing the inner
rings to the arms is by means of lugs welded on the arms, and to which the
rings are riveted.

485. _Q._--What are the scantlings of the paddle floats?

_A._--The paddle floats are usually made either of elm or pine; if of the
former, the common thickness for large sea-going vessels is about 2-1/2
inches; if of the latter, 3 inches. The floats should have plates on both
sides, else the paddle arms will be very liable to cut into the wood, and
the iron of the arms will be very rapidly wasted. When the floats have been
fresh put on they must be screwed up several times before they come to a
bearing. If this be not done, the bolts will be sure to get slack at sea,
and all the floats on the weather side may be washed off. The bolts for
holding on the paddle floats are made extra strong, on account of the
corrosion to which they are subject; and the nuts should be made large, and
should be square, so that they may be effectually tightened up, even though
their corners be worn away by corrosion. It is a good plan to give the
thread of the paddle bolts a nick with a chisel, after the nut has been
screwed up, which will prevent the nut from turning back. Paddle floats,
when consisting of more than one board, should be bolted together edgeways,
by means of bolts running through their whole breadth. The floats should
not be notched to allow of their projection beyond the outer ring, as, if
the sides of the notch be in contact with the outer ring, the ring is soon
eaten away in that part, and the projecting part of the float, being
unsupported, is liable to be broken off.

486. _Q._--Do not the wheels jolt sideways when the vessel rolls?

_A._--It is usual to put a steel