the advantage. It is impossible, however, to avoid
the conviction that the Dupuy de Lome would be a most
powerful and disagreeable enemy for either of the
eight great ironclads of Great Britain now building
to encounter on service. The Hood and Royal Sovereign
have many vulnerable points. At any position
outside of the dark and light colored portions of
armor plate indicated in our drawing, they could be
hulled with impunity with the lightest weapons.
It is true that gun detachments and ammunition will
be secure within the internal “crinolines,”
but how about the other men and materiel
decks? Now, the Dupuy de Lome may be riddled through
and through bf a 131/2 in. shell if a Royal Sovereign
ever succeeds in catching her; but from lighter weapons
her between decks is almost secure. We cannot
help feeling a sneaking admiration for the great French
cruising battleship, with her 6,300 tons and 14,000
horse power, giving an easy speed of 20 knots in almost
any weather, and protected by a complete 4 in. steel
panoply, which will explode the shells of most of our
secondary batteries on impact, or prevent their penetration.
In fact, there is little doubt that the interior of
the Trafalgar, whether as regards the secondary batteries
or the unarmored ends, would be probably found to
be a safer and pleasanter situation, in the event of
action with a Dupuy de Lome, than either of the naked
batteries or the upper works of the Royal Sovereign.
This is what Sir E.J. Reed was so anxious to
point out at the meeting of naval architects in 1889,
when he described the modern British battleship as
a “spoiled Trafalgar.” There was
perhaps some reason in what he said.—The
* * * *
DEMOLITION OF ROCKS UNDER WATER WITHOUT EXPLOSIVES-LOBNITZ SYSTEM.
[Footnote 1: Read before the Engineer’s
Club, Philadelphia. Translated from Nouvelles
Anodes de la Construction, March, 1890.]
By Edwin S. Crawley.
The methods of demolishing rocks by the use of explosives
are always attended by a certain amount of danger,
while at the same time there is always more or less
uncertainty in regard to the final result of the operation.
Especially is this the case when the work must be
carried on without interrupting navigation and in the
vicinity of constructions that may receive injury
from the explosions.
Such were the conditions imposed in enlarging the
Suez Canal in certain parts where the ordinary dredges
could not be used.
Mr. Henry Lobnitz, engineer at Renfrew, has contrived
a new method of procedure, designed for the purpose
of enlarging and deepening the canal in those parts
between the Bitter Lakes and Suez, where it runs over
a rocky bed. It was necessary to execute the work
without interrupting or obstructing traffic on the
The principle of the system consists in producing
a shattering of the rock by the action of a heavy
mass let fall from a convenient height, and acting
like a projectile of artillery upon the wall of a fortress.