e 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_ between
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 Engineer._

* * * * *

DEMOLITION OF ROCKS UNDER WATER WITHOUT EXPLOSIVES-LOBNITZ SYSTEM.[1]

[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