re convenient to use only a single row of battering rams. The
production was from about seven to eleven cubic meters (9.2 to 14.4
cubic yards) per hour. Toward the close of September, after it had
been demonstrated that the "Derocheuse" was capable of accomplishing
with celerity and economy the result for which it was designed, it was
purchased by the Suez Canal Company.

During the month of September, an experiment, the details of which
were carefully noted, extending over a period of sixteen days, gave
the following results:

Crew (33 men), 140 hours. 2,012.50 francs $402.50
Coal, @ 87.50 francs ($7.50) per ton 787.50 francs 157.50
Oil and supplies 220.00 francs 44.00
Fresh water, 16 days 210.00 francs 42.00
Sundries 42.50 francs 8.50
---------------- ---------
Total expense for removing 764
cubic meters (999.2 cubic yards), 3,272.50 francs $654.50

Average, 4.28 francs per cubic meter ($0.65 per cubic yard).

This result cannot be taken as a universal basis, because after a
year's use there are numerous repairs to make to the plant, which
would increase the average net cost. This, besides, does not include
the cost of removal of the dredged material, nor the depreciation, the
interest and the insurance.

It should be added on the other hand, however, that the warm season
was far from being favorable to the energy and perseverance necessary
to carry on successfully experiments of this kind. The temperature,
even at midnight, was often 38 deg. C. (100.4 deg. F.). Still further, the work
was constantly interrupted by the passage of ships through the canal.
On an average not more than forty minutes' work to the hour was
obtained. Notwithstanding this, there were extracted at Chalouf, on an
average, 38.225 cubic meters (50 cubic yards) per day without
interrupting navigation. At Port Tewfik, where there was much less
inconvenience from the passage of ships, the work was carried on from
eight to eleven hours per day and the quantity extracted in this time
was generally more than 76 cubic meters (99.4 cubic yards).

In most cases the system could be simplified. The engine which works
the dredge could, when not thus employed, be used to drive the pumps.
The propelling engine could also be used for the same purpose.

Th