EXPLOSIVES—0O’HERN, 259 
BURSTING CHARGES FOR PROJECTILES. 
In selecting an explosive suitable for use as a bursting charge for 
projectiles, conflicting conditions are encountered in that it must be 
sufficiently insensitive to withstand the enormous shock in being 
fired from the gun, and must at the same time be sufficiently sensitive 
so that it will be detonated without the use of so large a detonator as 
would in itself be dangerous in firing. Among the more important 
explosives which have been tested in this country at various times 
for use in filling projectiles may be mentioned nitroglycerin, blasting 
gelatin, picric acid, emmensite, joveite, maximite, trinitrotoluol, 
trinitrobenzine, and wet guncotton. The extreme sensitiveness of 
nitroglycerin and blasting gelatin were found to render their use 
exceedingly dangerous, and resulted in one instance in the destruc- 
tion of a $50,000 gun. Most of the other explosives mentioned were 
found too sensitive, too hygroscopic, or otherwise objectionable. 
While picric acid itself has not been greatly used, it has been em- 
ployed mixed with other substances such as nitronaphthaline, nitro- 
toluol, nitrobenzole, camphor, etc., and these mixtures have been used 
under various names such as lyddite, ecrasite, melenite, shimose, maxi- 
mite, etc. The explosive used in the United States service is a secret 
known only to those officials concerned in its procurement and use. 
It is designated as ‘‘Explosive D”’ as a tribute to its inventor, Lieut.- 
Col. B. W. Dunn, an officer of the Ordnance Department of the Army. 
This explosive can be readily manufactured and at a moderate cost, 
has excellent keeping qualities, can be easily loaded into projectiles, 
and is very powerful when detonated. It is so insensitive that it 
can be not only fired from a gun with absolute safety, but will with- 
stand the shock of impact on the hardest armor plate without 
exploding. 
ARMOR-PIERCING PROJECTILES. 
The sketch (fig. 2) shows the general construction of a modern 
projectile used for the attack of armor. The long-pointed outer 
covering for the head serves to greatly reduce the air resistance 
encountered in flight, and thus enables the projectile to reach the 
target with a higher striking velocity. The short inner cap is found 
to give the point such support as to greatly improve the chances for 
the projectile’s getting through a hard-faced plate unbroken. The 
head of the projectile proper is very hard, and at the same time very 
tough, two conflicting requirements. 
The difficult character of the acceptance tests for armor-piercing 
projectiles is evident from the fact that they are in general required 
to perforate unbroken a hard-faced armor plate at least as thick as 
the caliber, or projectile diameter. A 14-inch projectile is thus 
