the muzzle and the other for the
breech-purchase.

The muzzle-purchase block is so fitted as to be either shackled or
toggled to the housing-bolt above the port, and the breech-purchase
block has an iron strap terminating above, with an eye by which it is
shackled to a bolt passing through the deck above the gun. This bolt
has an eye in one end, and a screw or key-slit at the other, and, when
in place, is secured above the deck with a nut or key, between which
and the deck a washer of hard wood or iron of suitable breadth and
thickness is placed.

The hole through which this bolt is put should be directly above the
cascabel-block when the muzzle of the gun is under the housing-bolt,
and may be bored at the time the gun is to be dismounted; it is to be
stopped afterwards with a plug of wood coated with white-lead.

But as it is desirable that every division on the gun-deck should be
exercised in mounting and dismounting its guns, a hole may be made in
the deck above each division and bouched with a composition screw-tap.

The purchase-falls should not be less than three and a half inches in
size, and should be made of Manilla rope, of sufficient length to
reeve full, the gun being supposed to be on deck and the upper blocks
in place, allowing also sufficient end for splicing in the thimbles
and hitching the standing part of the purchase when rove.

An iron thimble, large enough to hook the double-block of a side or
train tackle, is spliced into the end of each purchase-fall.

SELVAGEE WADS.

214. Selvagee wads are made by the wad-machine at the Navy Yards. This
consists of pairs of disks adapted to each calibre of guns, which
being placed face to face on a spindle and keyed, present an annular
score, grooved in such a way as to make, when filled, a grommet of the
requisite size. Transverse notches are cut in the circumference of the
disks to the bottom of the score, for the convenience of marling the
wad before taking it off the mould.

[Illustration: SPACES REQUIRED for working DIFFERENT CLASSES OF GUNS
on PIVOT CARRIAGES. Lith. by J.F. Gedney, Washn. C.K. Stellwagen,
del.]

In making the wad, the end of a rope-yarn is fixed in the score, and
the mould is turned by a crank until the score is filled. The grommet
thus formed is marled like a selvagee strap, and a section of about an
inch is taken out of it, in order to make the wad, when swelled by
dampness, enter the bore of the gun readily.

Selvagee wads