THE APPARATUS ADAPTED FOR WAR AND DEFENCE. 101 
The carriage would be dispatched with all 
expedition, and in a short time arrive at the 
spot. Bnt, in the interim, the ship has gone 
on shore, and in such a situation that the 
only way of communicating is by means of a 
rope. In a few minutes the boat is detached 
from the carriage, the gun brought in opera- 
tion, and a line having been fired, the people 
are taken out, by means of the catamaran, 
before tiie vessel goes to pieces Many 
other examples might be adduced, which 
will appear evident to those who are acquaint- 
ed vvitli the dangers of a sea-coast. 
Finally, for war and defence of the coast, 
this apparatus would be eminently useful. 
Suppose each intermediate coast-guard sta- 
tion were furnished with a life-carriage, and 
that an attack from boats were anticipated 
at any point, bj'^ means of signals, a brigade 
of guns, served by the station men, might in 
a short time be formed, sufficiently strong to 
repulse even a very serious attack- Again, 
in the event of an army campaigning in a 
country intersected by rivers; and of their 
requiring not only artillery, but means to 
pass the aforesa'id rivers, a brigade of these 
machine-s, with flat-bottomed boats, would 
answer the purposes of both. By heaving 
lines across a floating bridge might in a 
time be constructed, thus superseding the 
use of pontoons. The guns of the carriages 
might, if required, be employed to cover 
the landing. 
THE CATAMARAN. 
The catamaran consists of tvvo copper 
boats, strongly joined together, as in fig. 4. 
Between them is an iron cradle 'see fig. 3). 
D D is the interior view of one of the boats ; 
A A is one of the frames of the cradle, fur- 
nished at the bottom with a flat iron sledge, 
and sliding freely in the slides B B. The 
bottom of the cradle is grated, and upon 
this the man stands : his weight being thus 
considerably below the line of floatation, or 
the centre of gravity, and the two boats act- 
ing in opposition to each other, the possibi- 
lity of upsetting is almost entirely removed. 
As the catamaran is represented in fig. 3. 
it is afloat; but when it takes tlie ground the 
cradle slides up, and the bottom coming on 
a level with the bottom of the boa-.s,- its 
passage over sand or shingle, when being- 
beached, is very easily effected. 
After the line from the gun has taken 
effect, the catamaran is hauled off by those 
on board, another rope attached to it beino- 
held by those on shore. ^ 
The catamaran will hold two or three 
persons, and is placed or carried in the life- 
boat when the machine is travelling. If 
used at night, a light may be attached to it, 
as in the life-buoy. 
. THE PNEUMATIC RAILWAY. 
(Continued from page 63, J 
It is well known that notwithstanding the 
prosperous condition of the Manchester Rail 
Road Company, yet their expenditure in loco- 
motive power has been so enormous as to cause 
considerable anxiety on the part of the Ma- 
nagers ; and some of them have even inclined 
to the opinion, that the question of stationary 
power deserves to be reconsidered. This 
opinion would probably be confirmed and 
strengthened, if the practicability of the 
pneumatic system were satisfactorily demon- 
strated by experiment upon a sufficiently large 
scale. 
On the whole, it appears to me that if the 
mechanical difficulties of maintaining the 
pneumatic tunnel sufficiently air-iight be over- 
come, the system presents a fair prospect of 
being practically successful. These difficul- 
ties are not so great as they may at first ap- 
pear. It should be recollected that nothing 
approaching to the exhaustion of the tunnel 
can be necessary ; nor even any considerable 
degree of rarefaction. Supposing the tunnel 
to have an internal diameter of 40 inches, the 
impelling diaphragm would have surface of 
about 9 square feet. If in such a tunnel a 
degree of rarefaction were produced suffi- 
cient to cause a parometiic gauge to fall 2 
inches (which would be an extremely slight 
degree of rarefaction indeed), an impelling 
force would be obtained amounting to one 
pound on every square inch of the snrffice of 
the diaphragm, which would give an impel- 
ling force of more than half a ton. It is cal- 
culated that on the common railways the 
amount of load is above 200 times the force 
of traction, and it would therefore follow that 
this force would be sufficient to draw a load 
of 100 tons. If an additional incli of mercury 
be made to fall in the barometric gauge to 
balance friction, &c., still the raretaction 
would be extremely inconsiderable, and the 
contrivances to prevent leakage would ap- 
pear to be attended with no great mechani- 
cal difficulty. 
From the various reasons which I have 
above stated, I am of opinion that the present 
project would, if carried into execution, be 
likely to be attended with greater economy 
and safety than any other method ot woiking 
railways now practised ; and I see no reason 
against the attainment of as much speed as 
is obtained by the locomotive engines. At all 
events, having explained the season on which 
I have grounded this opinion, every one can 
judge to what weight it may be entitled. 'J'he 
project would appear to be w ell deserving of 
trial on some railroad of limited length, such 
as that between London Bridge and Green- 
wich, where it would be sufficient to have 
stationary engines at the extremities. In 
such a case, I see scarcely any limit to the 
speed which might be attained with safety ; 
and the economy, as compared with locoma- 
live engines, would probably be very great. 
Dion. Lardner. 
H. D C. 
London, Feb, 19, 1835. 
