e pipe which it is desired to attach be
put through the leaden hause, and let the space between the pipe and the
lead be packed with gasket and white lead, to which a little olive oil has
been added. The pipe must have a flange upon it to close the hole in the
ship's side; the packing must then be driven in from the outside, and be
kept in by means of a gland secured with bolts passing through the ship's
side. If the pipe is below the water line the gland must be of brass, but
for the waste water pipe a cast iron gland will answer. This method of
securing pipes penetrating the side, however, though the best for wooden
vessels, will, it is clear, fail to apply to iron ones. In the case of iron
vessels, it appears to be the best practice to attach a short iron nozzle,
projecting inward from the skin, for the attachment of every pipe below the
water line, as the copper or brass would waste the iron of the skin if the
attachment were made in the usual way.

DETAILS OF THE SCREW AND SCREW SHAFT.

476. _Q._--What is the best method of fixing the screw upon the shaft?

_A._--The best way is to cut two large grooves in the shaft coming up to a
square end, and two corresponding grooves or key seats in the screw boss
opposite the arms. Fit into the grooves on the shaft keys with heads, the
length of which is equal to half the depth of the boss, and with the ends
of the keys bearing against the ends of the grooves in the shaft. Then ship
on the propeller, and drive other keys of an equal length from the other
side of the boss, so that the points of the keys will nearly meet in the
middle; next burr up the edge of the grooves upon the heads of the keys, to
prevent them from working back; and finally tap a bolt into the side of the
boss to penetrate the shaft. Propellers so fitted will never get slack.

477. _Q._--What is the best way of fitting in the screw pipe at the stern?

_A._--It should have projecting rings, which should be turned; and cast
iron pieces with holes in them, bored out to the sizes of these rings,
should be secured to the stern frames, and the pipe be then shipped through
all. Before this is done, however, the stern post must be bored out by a
template to fit the pipe, and the pipe is to be secured at the end to the
stern post either by a great external nut of cast iron, or by bolts passing
through the stern post and through lugs on the pipe. The pipe should be
bored throughout its entire length, and the s