The sounding apparatus, the Brothergood engine for actuating it, and the
electric light apparatus were placed upon the bridge. The operating
of the sounding line and of the electric light was therefore entirely
independent of that of the dredges. On the foremast, at a height of
about two meters, there was placed a crane, F, which was capable of
moving according to a horizontal plane. Its apex, as may be seen from
the plan of the boat, was capable of projecting beyond the sides of the
ship, to the left and right. To this apex was fixed a pulley over which
ran the cable that supported the dredges or bag-nets, which latter were
thus carried over the boat's sides.

[Illustration: FIG.3.--DIAGRAM OF THE THIBAUDIER SOUNDING APPARATUS.]

The preliminary operation in every submarine exploration consists in
exactly determining the depth of the sea immediately beneath the vessel.
To effect this object different sounding apparatus have been proposed.
As the trials that were made of these had shown that each of them
possessed quite grave defects, Mr. Thibaudier, an engineer of the navy,
installed on board the Talisman last year a new sounding apparatus which
had been constructed according to directions of his and which have given
results that are marvelous. The apparatus automatically registers the
number of meters of wire that is paid out, and as soon as the sounding
lead touches bottom, it at once stops of itself. This apparatus is shown
in Fig. 4, and a diagram of it is given in Fig. 3, so that its operation
may be better understood. The Thibaudier sounding apparatus consists of
a pulley, P (Fig. 3), over which is wound 10,000 meters of steel wire
one millimeter in diameter. From this pulley, the wire runs over a
pulley, B, exactly one meter in circumference; from thence it runs to a
carriage, A, which is movable along wooden shears, runs up over a fixed