The Navy time-fuze is rarely extinguished by several ricochets on water; and near the end of its flight, when fired direct, frequently acts by concussion.
The fuze used should not be of longer time of burning than requisite to reach the object; the shorter times are of quicker composition, therefore more certain; also in firing on ricochet the shell may sink short of the distance necessary for its explosion, and consequently be supposed to fail.
327. For special firing, as for example at shore-batteries or masses of uncovered troops, any of these fuzes may be shortened. To do this, unscrew the water-cap and back the paper case out from the lower end with a drift and mallet; cut off from the lower end with a fine saw, or sharp knife struck with a mallet, the proportional part required, and insert the upper part in the stock, forcing it down with a few gentle blows with the drift; screw on the water-cap. It is preferable, however, when circumstances will admit, to take up such distance as will correspond with the time of flight of one of the regulation lengths. When firing against ships or earthworks, the fuze should be a little longer than necessary, in order to reach the object before bursting; but a little shorter when firing against boats or masses of troops, in order to insure its bursting in front of them.
328. The Bormann fuze is fitted to the 24-pdr. and 12-pdr. howitzer ammunition, and all shrapnell. It has also been fitted to certain shells used for special firing. The length of fuze is the limit of the distance within which this fire is effective.
This fuze is opened at the required number of seconds, by cutting close to the right of the mark on the index-plate. The cut should be made down to the plane of the table, in order to expose the composition; and is best made at two or three efforts, instead of trying to effect the cut at once. This fuze should be carefully explained to the men, as shells have been taken from guns with the cut made into the priming-magazine, which would explode them at the muzzle.
329. There are also on trial for the rifled cannon the percussion and time fuzes of Schenkl, Hotchkiss, Parrott, and others.
No reliable percussion or concussion-fuze has as yet been arranged for spherical shells.
330. These fuzes will be exhibited and explained by the Ordnance Officer on the application of Commanders of vessels, who, with the Executive Officer and Gunner, are enjoined to make themselves thoroughly acquainted with this most important part of the equipment.
331. Commanders of vessels will carefully note and report the efficiency of all fuzes fired in action or exercise; giving the elevation of the gun, the estimated or measured range, the number fired, the name of the inventor, whether percussion or time, the number of failures to explode the shell, premature explosions, and satisfactory action. Great waste of ammunition is frequently occasioned by an under-estimate of the distance.
332. The times of flight and length of fuze for all projectiles, so far as ascertained at the Experimental Battery at Washington, are given in the Table of Ranges, [Appendix B.]