Q. Give the weight of charge, weight of projectile, and initial velocity of the piece to which your company is assigned.
A. See table on page 75. (Ref. Ordnance Department, G. O. 9, W. D. '08.) Slight variations from the requirements of this table will be permitted; but it is desired that these requirements shall be fulfilled as nearly as practicable.
Q. Name the different kinds of primers.
A. Common friction, common electric, obturating friction, obturating electric, and combination electric friction.
Q. Explain the action of the common friction and the obturating friction primer.
A. Its action consists in the friction of a saw-tooth wire being pulled through a portion of mercuric fulminate, which explodes and ignites a small charge of powder in the primer, which in turn ignites the main charge in the gun. (See Figs. 34 and 35.)
Q. Explain the action of the common and obturating electric primer.
A. Two insulated wires entering the primers are joined by a platinum wire. (A little guncotton is sometimes imbedded around the platinum wire.) The current heats the platinum, which ignites a small charge of powder or fulminate, if it be a common electric, in the primer, which ignites the main charge. (See Figs. 36 and 37.)
Table of Charges, Velocities, etc., for Rapid-fire and Seacoast Guns.
Weights of projectiles, powder charges, muzzle velocity, and pressure for rapid-fire and seacoast guns, service and practice charges.