Mr. Poillon attributes the small effective performance to the system employed for putting the water in motion.  At time of Mr. Seraing’s experiments, only centrifugal force pumps were known, and the theoretic effective duty of these, whatever be the peculiar system of construction, cannot exceed 66 per cent., and, in practice, falls to 40 or 50 per cent. in the majority of cases.

It is probable, then, that in making use of those new rotary pumps where effective duty reaches and often exceeds 80 per cent., we might obtain much better results, and it is this that justifies the new researches that have been undertaken by Messrs. Maginot & Pinette, whose first experiments we are about to make known.

In order to have it understood what interest attaches to these researches, let us state the principal advantages that this mode of propulsion will have over the helix and paddle wheel:  The width of side-wheel boats will be reduced by from 20 to 30 per cent., and the draught of water will be diminished in screw steamers to that of the hull itself; the maneuver in which the power of the engine might be directly employed will be simplified; a machine will be had of a sensibly constant speed, and without change in its running; the production of waves capable of injuring the banks of canals will be avoided; the propeller will be capable of being utilized as a bilge pump; all vibration will be suppressed; the boat will be able to run at any speed under good conditions, while the helix works well only when the speed of the vessel corresponds to its pitch; it will be possible to put the propelling apparatus under water; and, finally, it will be possible to run the pump directly by the shaft of the high speed engine, without intermediate gearing, which is something that would prove a very great advantage in the case of electric pleasure boats actuated by piles and accumulators and dynamo-electric machines.

[Illustration:  NEW STEAMER PROPELLED BY HYDRAULIC REACTION.]

We now arrive at Messrs. Maginot & Pinette’s system, the description of which will be greatly facilitated by the diagram that accompanies this article.  The inventors have employed a boat 14 meters in length by 1.8 m. in width, and 65 centimeters draught behind and 32 in front.  The section of the midship beam is 70 square decimeters, and that of the exhaust port is 4.  At a speed of 2.2 meters per second the tractive stress, K, is from 10 to 11 kilogrammes.  At a speed of 13.5 kilometers per hour, or 3.75 meters per second, the engine develops a power of 12 horses.  The piston is 19 centimeters in diameter, and has a stroke of 15 centimeters.  The shaft, in common, of the pump and engine makes 410 revolutions per minute.  It will be seen from the figure that suction occurs at the lower part of the hull, at A, and that the water is forced out at B, to impel the vessel forward.  C and C’ are the tubes for putting the vessel about, and DD’ the tubes for causing her to run backward.  Owing to the tubes, C, C’, the rudder has but small dimensions and is only used for directing the boat.  The vessel may be turned about in situ by opening one of the receiving tubes, according to the side toward which it is desired to turn.