It will be seen that the general principle applied for utilizing the motive power is that of direct action. It has already been employed in a few analogous apparatus constructed by Sir William Armstrong, especially those of the arsenal of Spezia and of the Elswick cannon foundry, but solely for the lifting press. This is the first time that use has been made of it to effect the oscillating motion corresponding to the horizontal shifting of the load. This was formerly done through the intermedium of a mechanism that, aside from its complication and higher cost, presented the inconvenience of absorbing a large quantity of force in friction; besides, the direct action permits of performing the maneuvers much more quickly by the use of the water in reserve contained in the accumulators. Another important improvement, likewise due to the Compagnie Fives-Lille, consists in the addition of safety clicks, which engage with racks parallel with the piston rod of each of the presses and movable with it. The clicks, on the contrary, are jointed to axes fixed on the bottom of the cylinders. This arrangement presents the following advantages: If a leakage occurs in the joints or feed pipe of the hoisting press, the descent of the load can be stopped instantaneously, thus preventing the grave damage that would be done to ships and even to the shears themselves by the descent of a 120 ton load, however slow it might be. As regards the oscillating press, this arrangement permits of fixing the base of the connecting beam at any point whatever of its travel, when it is desired to dismount the piston. Further, it permits of maintaining the shears in an invariable position in case of sudden damages to the piping. [Illustration: FIG. 3.--AUTOMATIC MULTIPLIER.] In order to produce the three powers of 25, 75, and 120 tons required by the programme, and at the same time expend in each case a corresponding quantity of water under pressure, it is of course necessary to cause the pressure of the motive water to vary in the same proportion as the stress to be extended. This result is reached by calculating the diameter of the two cylinders in such a way as to obtain the mean power of 75 tons, in making the water of the general conduit act directly under the normal pressure of 50 atmospheres. For the powers of 25 and 120 tons, use is made of an automatic multiplier, that consists of two cylinders arranged end to end, in which move pistons, A and B (Fig. 3), of different diameters. When it is a question of lifting 120 tons, the water at 50 atmospheres actuates the piston, A, and the other forces into the lifting cylinder motive water under a much greater pressure. If the load to be lifted is but 25 tons, the water at 50 atmospheres actuates the piston, B, and A forces the water into the same cylinder at a much lower pressure. The same operations are effected in the other cylinder when the extreme loads of 25 and 120 tons are moved.