nd measured, inside and out,
for defects of metal or manufacture, and the results recorded in the
prescribed forms by the Inspector resident at the foundry, as soon
after being finished as possible, if he has not already done so in the
various stages of manufacture, which is preferable, as the detection
of errors which pass the limits of toleration may save useless
subsequent labor. Internal defects of metal will, for instance,
generally be betrayed by a close examination of the core-pieces. As
rust tends to conceal defects, this examination of the guns is to take
place before exposure to the weather. And previously to the final
examination and proof of guns, they are not to be covered with paint,
lacquer, oil, or any material which may hide defects of metal.

If it is ascertained that any attempt has been made to conceal
defects, the gun or guns so treated are to be rejected without further
examination.

As the water-proof, which is of great importance in detecting defects
of metal not otherwise developed, necessarily succeeds immediately the
powder-proof, and can be effectively applied only in fine weather, and
when the temperature is above the freezing-point, final inspections
are to be made at such times only.

DESCRIPTIVE LIST OF INSTRUMENTS REQUIRED AND USED IN THE INSPECTION
AND PROOF OF GUNS.

28. 1st. A mirror for reflecting the sun's rays into the bores. Two
will be required if the sun be in the rear of the Inspector.

2d. A lamp attached to a staff for examining the bores when the sun is
obscured, or the guns are under cover.

3d. A standard cylinder gauge. This is a hollow cylinder of iron,
turned to the least allowed diameter of the bore, and one calibre in
length. It has a cross-head at each end, one of which has a smooth
hole through its axis to fit the staff, and the other is tapped to
receive the screw in the end of it.

[Illustration: DAHLGREN SHELL GUN
PARROTT RIFLE GUN 1864.
D. Van Nostrand Publisher. Julius Bien, pr.]

4th. A measuring-staff of steel or iron, in joints of suitable length,
connected together by screws. Each joint is provided with a light
brass disk, the diameter of which is 0.05 inches less than that of the
bore. Through the centre of the disk there is a hole which fits upon a
shoulder at the joint; the whole is so arranged that when the joints
are screwed together the disks between them are held firmly in place,
while the length of the staff is not affected by them.