9 
strated at the experiments at Chalons in 1887 when armoured towers with cupolas 
93” thick, were put out of action by a mortar of 10°5” calibre firing high 
explosive shell from a distance of 1200 yards, while it was estimated that at 
the same range it would take from 800 to 1000 rounds from a 5°8” gun with 
common shell to produce a like effect. The frontal attack of armoured works 
then should be carried out by curved fire from medium and heavy howitzers. 
placed in concealed batteries at ranges of from 1200 to 1600 yards and 
firing high explosive shell, and it is only when suitable positions cannot be found 
within those limits that recourse should be had to direct fire from 5” or 6” euns. 
For guns mounted behind armoured shields direct fire from guns of 5” or 6” 
calibre at ranges not exceeding 1750 yards canbe used. At 1750 yards the 5°85” 
common shell 2°8” calibres long from a 5:85” gun 25 calibres in length will per- 
forate 6°669" of iron if smokeless powder is used and 5°967” with ordinary powder. 
Heavier guns need only be used against defences of exceptional strength or when 
the demolition batteries have to be placed at a greater range than 1750 yards. 
Curved fire from howitzers of 8:19" or 8°58” will be suflicient for the destruc- 
tion of magazines and shelters protected by concrete of medium thickness ; only 
when this exceeds 78” need shell with a greater bursting charge than 60 lbs. of 
melinite, from mortars of 10°34" or 10°92” be used. 
Artillery action against the defensive artiilery in the intervals.— 
The direct fire of the guns of the first and second échelon placed on or slightly 
behind the crest line of the main line of defence must be silenced by similar fire 
from guns, curved or indirect fire must however be relied on to silence the fire of 
the concealed batteries of the 3rd ¢chelon. 
Tf an efficient system of fire observation by captive balloons or other means 
has been organized this can be effected by comparatively light guns and howitzers 
at ranges even as great as 4600 yards, and with such a wide margin the besieger 
should have no difficulty in concealing his batteries from the view of the direct 
fire guns in the intervals or in the forts, but it is absolutely essential that there 
should be accurate means of observing and correcting the fire. 
Obstacles and the accessory defences of the forts must be destroyed by curved 
fire, and the terrepleines and trenches searched by curved shrapnel fire—once the 
forts are rendered untenable and their guns silenced the defences in the intervals 
deprived of flanking support must soon fall. 
The attack on the second line of defence will be carried out in a similar way. 
If the fortifications are of a type anterior to those designed to withstand the 
latest developments of artillery fire, that is to say, if the forts have parapets of con- 
siderable length and great relief, if their guns are not protected by armour and 
their magazines, &c. not proof against high explosive shell; lighter guns and 
howitzers firing such shell and a less deliberate bombardment will suftice to reduce 
them. The siege will be much less protracted and the fortifications will have failed 
to accomplish their main object, viz. that of detaining or demobilizing a portion 
of the invading army for a considerable time. 
Some experiments were recently carried out at Schoorl in Holland to test the 
penetration of high explosive shell into concrete, and to ascertain the best com- 
position for concrete and the most suitable thickness for bomb-proof roofs, &e. 
The ordnance used were— 
(a) Rifled mortar 8°19" 7 calibres long, range 3775 
633 to 684 f.s., angles of descent between 52° 45 
velocities between 594 and 618 fs. 
(2) 5°85" gun 24: calibres long, range 540 yards, striking velocity 1320 f.s. 
Projectiles— 
(a) Steel shell 8°19''5 calibres long, weight 341 lbs., bursting charge 46°2 lbs, 
guncotton or 50°6 Ibs, bellite, 
yards, muzzle velocity 
and 60° 40’, striking 
