182 REPORT—1862. 
been suggested that if, instead of employing a given thickness of iron in one solid 
piece, the armour of a ship were divided into two plates, each of half that thick- 
ness, and these plates were separated by a certain space from each other, the resist- 
ing power of the structure might be much increased. The theory was that the first 
plate, though it would doubtless be pierced, would so deaden the force of the shot, 
that the second plate would repel it; and, indeed, as regards solid shot, the ques- 
tion remains still undecided. With respect to shell, however, or rather Mr. Whit- 
worth’s shells, we are not left in doubt even on this point. The 70-pounder was 
trained against a target constructed on this principle of a double side. A stron 
oak frame, armed with 4-inch plates, was attached to a second plated to the dept 
of 2 inches, an interval of two or three feet being left between them. The shell 
from this gun, fired with 12 lbs. of powder only, pierced the outer side of the target 
completely, oak and iron together, after which it burst inside the frame and shat- 
tered it to pieces.” 
From this statement we learn, that 4 inches of solid iron and 9 inches of wood 
are no protection against shells discharged from a moderately sized gun, and that no 
unboat, such as those on the American waters, could preyent the entrance of these 
eaded and destructive missiles. In point of fact, Mr. Whitworth, with a rifled 
gun lighter than the 68-pounder, could destroy them by his steel-hardened shells 
at a distance of 1500 to 2000 yards, 
Since the above was written another experiment has been made with a still larger 
gun, rifled on Mr. Whitworth’s hexagonal principle. This gun was of large calibre, 
120-pounder, at a distance of 600 yards, and the results seem to prove that the 
side of a vessel like the ‘ Warrior’ is no longer shell-proof. In these experiments 
130-Ib. solid shot, with a charge of 25 lbs, of eile d went right through the 43- 
inch armour-plate and lodged in the teak backing behind, A shell of the same 
weight, and a charge of 25 lbs. of powder, also penetrated the armour-plate and 
exploded, tearing the wood backing, and lodged on the opposite side. 
From these more recent experiments we may infer that the victory is on the side 
of the gun, and that it may be difficult, under such fearful odds, to construct ships 
of sufficient power to prevent their destruction by the entrance of shells. Other 
experiments are, however, in progress, and means may yet be adopted to solve the 
question of armour-ships versus shot and shell. 
On the Importance of Economizing Fuel in Iron-plated Ships. By B. E. Aten. 
Tron-plated ships, to be efficient, ought to be able to carry coals for fourteen days ; 
but in consequence of the weight of the armour, and the present mode of generating 
and using the steam, only coals enough for seven days can be carried. In future 
wars, despatch in going to the seat of war, and high speed in manceuvring, will be 
necessary ; therefore much fuel must be used ; hence the desirability of studying 
how to economize fuel. The deficiency of boiler-power in the Royal Navy is too 
well known. Modern inventions have increased the displacement of ships: thus, 
the armour, coals, and machinery are about equal in weight; and 1000 horses’ 
pone will consume 200 tons of coal a day, under full steam, say at ten knots per 
our; but the necessary power for increasing the speed from ten to twelve knots 
demands double the fuel; and if the speed be increased to sixteen knots, the amount 
of fuel must be quadrupled. Some of our new war-ships only move at 93 knots an 
hour, whereas it is generally allowed they should make 15 knots ; 5000 miles ought 
to be steamed without re-coaling, but only one-third of that distance can be accom- 
plished. As a proof that the ‘boilers are too small, it may be affirmed that none 
of the ships in the Royal Navy can work full steam, and keep the throttle-valves 
open, for more than a few hours at a time. Six-hundred horse-power boilers should 
be used where only 400 horse-power boilers are now used. Coal is the only item 
in which weight can be saved. The merchant vessels only consume half the coals 
(for ships of the same size) of those in the Royal Navy. Cornish engines consume 
2; pounds of coal per horse-power per hour; 23 pounds ought to be the limit in 
marine engines; but 6 poner are generally used in the Royal Navy. He proposed 
the following methods for economizing fuel :—To proportion the boilers to the steam 
required ; to increase the capacity of the cylinders, but not the length of the stroke ; 
. 
