Record of firing with 12-inch B. L. rifled mortar (cast-iron), South Boston Iron-Works, at Sandy Hook, N. J., October 3, 1889.

[Object of firing: to test mortar.]

Breech-block closed and opened eas-
ily; obturation good.

Present, Col. H. L. Abbot, Col. H. W. Closson, clair representing the South Boston Iron-Works.

*Du Pont's Sphero-Hexagonal, O. X. C. Density, 1.795; granulation, 100.

and Lieut. Col. A. Mordecai, on part of the Board of Ordnance and Fortification, and Mr. W. P. Hunt, jr., and Mr. H. SinCol. H. L. Abbot and Col. H. W. Closson not present at round 7.

Record of firing with 12-inch B. L. rifled mortar (cast-iron), South Boston Iron-Works, at Sandy Hook, N. J., October 4, 1889.

* Du Pont's Hexagonal E. V. K. Density, 1.750; granulation, 72.

+ Du Pont's Sphero-Hexagonal O. X. C. Density, 1.795; granulation, 100.

Record of firing with 12-inch B. L. rifled mortar (cast-iron), South Boston Iron-Works, at Sandy Hook, N. J., October 5, 1889. [Object of firing: to test mortar.]

14 (*)

Pounds.

Pounds.

Feet.

Feet.

Feet.

Feet.

965

A

50

624

91.6

0 5

965

27, 550

45

38

965

B

26, 950

953

A

20

20 (4)

Appendix E.

EXPERIMENTS WITH HIGH EXPLOSIVES.

WASHINGTON, D. C., June 5, 1889. GENERAL: The committee appointed at the last meeting of the Board has the honor to submit the following report:

Experiments with high explosives for use of bursting charges of shells may be regarded by the Board from two points of view: (1) as a matter of investigation to determine experimentally many points now doubtful as to the physical properties, and best modes of treating types; and (2) as a matter of testing to determine the merit of the several devices submitted by inventors. It is desirable that these investigations and tests should be carried forward together and at once.

High explosives will be used in two different kinds of shells, viz: armor-piercing and common. The difficulties to be overcome with the former are vastly greater than with the latter. Moreover the necessity for piercing armor is less than formerly, because the area heavily plated on war ships is becoming less and less. Thus only about half of the water line is protected by armor in recent British types, and in French ships even the guns themselves are often fired from exposed barbettes. The chief dependence against sinking is in the under-water armored deck, usually about 3 inches thick, and the water tight compartments. The experiments now in progress with the Resistance in England demonstrates that the effects of common shell even of small calibers, charged with high explosives, are disastrous when occurring within the unarmored part of the hull. Finally, the expense of iron plates for targets for the armor-piercing class is so great that it appears to be wise for us to begin with common shell, and leave armor-piercing trials for a later date.

For successful use of high explosives in common shells three elements must be considered: (1) the envelope, (2) the explosive, (3) the igniting mechanism.

Cast iron as a material for the envelope is too uncertain to command confidence when the result of a slight defect may be the destruction of the gun by premature explosion. Even in experimenting, experience has shown that no doubt as to the character of the projectile should be tolerated. It is therefore advised that those to be ordered be made of good open-hearth steel.

As to patterns, it is desirable that such be chosen as can be fitted to receive different internal arrangements for loading. Those of the Ordnance Department marked "Ordnance Board, U. S. Army, Governors Island, December 24th, 1888," and "January 7th, 1889," are well suited for the projected trials, and are recommended for adoption, They have

the Eureka sabot for use in muzzle-loading guns; and the following are the more important dimensions.

As to the explosive, we have now before the Board explosive gelatine, gun cotton, Emmensite, the Schwalm mixture, dynamite, and Americanite, or the Smolianinoff compound.

Experiments of the kind to be undertaken involve no little time, labor, and expense, and they should therefore be restricted to what promise ultimate success. This is not the case with the Americanite, because the liquid form and the liability to become dangerous through evaporation or by lying in store would forbid its use in the military service, unless trials should demonstrate that no other variety free from these objections can be so used. That this explosive is liable to deterioration has been proved to the satisfaction of your committee by the results of a personal examination of a sample left in store at Sandy Hook after the trials made by the Ordnance Board in November, 1887. This sample is contained in a glass bottle, stored in a magazine of the fort. On April 5, 1888, a surface stratum of different appearance from that below was noted by Col. Mordecai. It was then half an inch 'thick. On July 10 it was fifteen thirty-seconds of an inch thick. On January 3, 1889, it was fully half an inch thick. On March 26, 1889, the date of our inspection, it was seven thirty-seconds of an inch thick, the whole height being 6 inches. Samples of the two strata were then carefully taken with a pipette and at once tested with a hammer on an iron slab. The upper gave no decrepitation, but the lower acted in all respects like pure nitroglycerine, except that it was perhaps a trifle less sensitive. Stirring the mixture with a glass rod produced no apparent change or recombination of the fluid; but at a subsequent examination, on June 1, a great change had occurred. The appearance then was for 2 inches at the bottom a white fluid; above that for about 1 inch a cloudy combination of white and yellow fluid; the remaining fluid to surface was of uniform yellow color. An explosive possessed of such characteristics would be extremely dangerous in a loading room, and your committee therefore recommends that the action already taken by the Board on March 14th, 1889, in advising that experiments with this explosive be deferred for the present be adhered to. As to dynamite, it is well known to be far more sensitive to shocks than others on the list, and as none of the inventors seem to prefer it to explosive gelatine for testing their loading devices, it is recommended that it be left untried for the present. This reduces the list to explosive gelatine, gun cotton, Emmensite, and the Schwalm mixture. As to the igniting mechanism, the following conditions should be fulfilled by a pattern suitable for use in coast defense. The class of fuse should be percussion, with base action and a slight delay action, and with a sensitiveness adjusted for a projectile striking the unarmored side of a war ship. To insure an explosion of the first order in the charge of the shell, a detonating primer of great intensity is essential. An initial explosion of mercuric fulminate, say 10 grains, in a large