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 inch from the bore. This is to be pierced lengthwise to receive the wire.
TO TAKE THE IMPRESSION.
36. Shove the wire through the vent; let it pass along the bore and out at the muzzle; put it through the leaden button and tie a knot at the end. Draw the wire back through the vent until the leaden button is introduced firmly into the inner orifice.
Lith. by J.F. Gedney, Washn.