The vessel, as shown by her plan in Fig. 2, had to undergo important alterations for the cruise that she was to undertake. Her deck was almost completely freed from artillery, since this would have encumbered her too much. Immediately behind the bridge, in the center of the vessel, there were placed two windlasses, one, A, to the right, and the other, B, to the left (Fig. 2). These machines, whose mode of operation will be explained further along, were to serve for raising and lowering the fishing apparatus. A little further back there were constructed two cabins, G and HH. The first of these was designed to serve as a laboratory, and the second was arranged as quarters for the members of the mission. 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 pulley, K, and reaches the sounding lead, S, after traversing a guide, g, where there is a small sheave upon which it can bear, whatever be the inclination of the boat. The wheel, B, carries upon its axle an endless screw that sets in motion two toothed wheels that indicate the number of revolutions that it is making. One of these marks the units and the other the hundredths (Fig. 5).