roller in. | 4.5 | 3.6
{ of axle-pin in. | 9.5 | 7.5
{ of roller in. | 4.5 | 3.4
{ of socket in. | 2.9 | 2.5
Diameter { of hole in socket in. | 2.6 | 2.25
{ Small end of handle in. | 1.5 | 1.50
{ of hole for axle-pin in. | .75 | .62
Width { of roller in. | 3.60 | 3.00
{ Exterior of head in. | 9.00 | 7.00
Weight lbs. | 32. | 19.5
------------------------------------------------+---------+--------

IMPRESSION-TAKERS.

239. All vessels carrying XI and IX inch guns, and all iron rifles,
are to be furnished with an impression-taker and wax. Impressions of
the vent and bore, as described in Art. 57, are to be taken after
every ten shotted rounds in practice, and at the close of an action.
The last one should be preserved for comparison with the succeeding
one; and when, in the opinion of the Commanding Officer, the wear
becomes excessive, or a decided crack shows itself, a duplicate must
be forwarded to the Bureau for examination. In forwarding them, they
should be tacked on a piece of thin board secured in the bottom of a
box. If wrapped in cotton or oakum they are generally defaced. The
date, number of fires, Register Nos. of guns, ship from which
forwarded, and other remarks written and pasted on the under side of
the box-cover.

In expert hands any small spar--such as a boat's mast--will take the
impression equally well.

PASSING-BOXES.

240. Passing-boxes are to be made of strong and well-tanned harness or
sole leather, strongly sewed, or of such other material as may be
directed.

For 8-inch and 32-pounder guns they are to be of sufficient height to
contain two near-firing charges.

Their diameters, in the clear, must be half an inch greater than those
of the cartridges they are to contain.

Their tops must be distinctly lettered, in letters one inch and a half
long, with the calibre and class of gun they are intended to serve,
and made to slide on the beckets.

241. All passing-boxes are to be painted black, with the calibre and
charge painted in white letters two and one-half (2-1/2) inches long
on the side, and one and one-half (1-1/2) on the top.

242. If, however, there are any guns of the same calibre on spar-d