he upper jaw, the cascabel block and head of the pin,
the foundry number in quarter-inch figures.

The foundry number is also to be marked on the right rimbase.

Guns rejected for imperfections of any kind will have the letter C.
stamped on the anchor, so as to partially obliterate it.

The founders are to be dissuaded from selling such guns to other
parties, and required to break them up.

Guns rejected for such defects as render them dangerous to those who
fire them, should be irreparably mutilated, with the consent of the
founder.

EXTREME PROOF OF TRIAL-GUNS.

34. The extreme proof of guns intended for trial of metal, subject to
such modifications by the Bureau as future experience may dictate,
will be conducted as follows:

A suitable 'butt' shall be erected to arrest the flight of the
projectiles used in proof, and to admit of their easy recovery, and a
bomb-proof, readily accessible, for the protection of the firing
party.

When practicable, the 'butt' should be made thick enough to allow the
shot to just pass through, and be stopped by another beyond it,
without penetrating the latter; this is, for XI-inch, about 12 feet.

With care, it is estimated that 130 shells may be fired 1,000 times,
at the rate of one hundred rounds, per day.

After undergoing the ordinary proof established for its calibre and
class, the gun selected for extreme proof shall be subjected to at
least 1,000 rounds with service charges.

It may be fired from the skids, or suspended, as the Bureau may
direct.

During the trial the gun shall be frequently and critically examined,
inside and out, for cracks or defects, especially about the interior
orifice of the vent, of which impressions are to be taken in wax at
regular intervals, in the manner prescribed on page 16, or in such
other manner as the Bureau may direct. If they show that the vent is
corroded in furrows, and enlarged considerably in diameter at its
junction with the bore, a permanent impression is to be taken in lead,
to show the conical enlargement. The following manner, practised at
the Experimental Battery at Washington, is recommended:

IMPLEMENTS REQUIRED.

35. 1. A soft wire about 0.07 in. in diameter, and 3 or 4 fathoms
long.

2. A lever about twice the length of the bore, and about 3 inches in
diameter, and shod to suit the curve of the bore nearly.

3. A small button of soft lead, judged to be of sufficient size to
fill the vent at least one inc