10 
(4) Steel common shell 5:85”, 2°8 calibres long, weight 69-46 lbs., bursting 
charge 3°85 lbs. powder. 
(c) Armour piercing shot 5°85”, weight 84°75 lbs. 
The objectives were—structures used in fortification such as caponieres, maga- 
zines, &c. ‘The walls being built of brick rubble, and brick and cement concrete, 
the roofs were made of gravel concrete. 
The conclusions arrived at were— 
(1.) The best composition for concrete was found to be— 
1 volume of cement. 
Logg 59, Seana, 
jae ons », small stones or gravel. 
(2.) The necessary thickness for vaulted concrete roofs when the span is 
under 53 yards is 4’ 104” and even for greater spans the thickness need 
not exceed 6’ 6”. 
(3.) The use of panels or plates of iron °39" thick to strengthen the in- 
terior of the roofs is recommended, it enables the building to be held 
even after fissures have appeared through the concrete and does away 
with any danger from the fall of detached masses. 
(4.) The material for the walls in the concrete recommended in (1) or 
brick and cement concrete the thickness of the walls exposed to fire 
should be about 46” inches. 
(5.) Rubble revetments present a fairly efficient protection against direct 
fire with common shell. 
(6.) The best means of strengthening old type masonry or brick struc- 
tures is by covering them immediately with a layer of concrete, the 
interposition of a layer of sand which has been advocated was found to 
be not ‘only useless but detrimental. 
(7.) Wire entanglements were found to be the best kind of obstruction 
on account of their comparative indestructability even when subjected 
to fire with high explosive shell. 
(8.) For the attack of covering masses of loose earth or sand, sensitive 
fuzes are to be preferred to delay action, for the explosion of high 
explosive shell. 
A 6:045" shell with a bursting charge of 26-2 Ibs. melinite exploded by means 
of a delay action fuze formed a crater varying from 4'104” to 6'6” in diameter 
while with sensitive fuzes the crater was 22' 1” across and 6’ 9" deep. 
