The construction of the new sluice presented great difficulties, by reason of the fact that it was necessary to avoid obstructing navigation in the existing sluice, where the boats stood thirteen or fifteen feet above the laborers who were working at the side, behind simple dikes. Yet it became necessary to forbid the passage of the sluices for nearly a month each year. At Suresnes this was taken advantage of each time to keep the works in full blast during the whole night, the lighting being done by electricity. During these interruptions the boats accumulated at the sides of the dam, and gave the public an idea of what Paris would be as a sea port. All the work is now finished. Its estimated cost is six millions, two of which were devoted to the construction of about half a mile of dock wall and of a long and wide sewer. The sluices were opened for navigation on the 15th of September last. The new dams will be in operation in 1885, and next summer they will increase the height of water in Paris by one meter.--_L'Illustration_. [Illustration: IMPROVEMENT OF THE RIVER SEINE.--THE NEW DAM AT SURESNES.] BREAREY'S AERONAUTICAL MACHINE. Mr. Fred. W. Brearey has been the honorary secretary of the Aeronautical Society of Great Britain ever since its establishment in 1866. In the course of his experiments, extending over some years, he found that if a serpentine action were imparted to a fabric it would propel an attached object many times its weight in the air. He records in his published magazine articles that he took the idea from watching the movements of a skate in an aquarium, which in swimming undulated its whole body. [Illustration: BREAREY'S FLYING MACHINE.] In applying the principle to locomotion in air, it is of course impossible to undulate what may called the backbone of the whole structure in the manner of the skate. But a fabric may be so attached to a receptacle, and so worked from thence by a suitable motive power, that its undulations will propel and support a considerable weight, depending upon the energy with which such fabric is thrown into waves. He believes that the awning of a vessel can be made in this way to contribute to a ship's progress at the same time that it would cool the passengers. Mr. Brearey argues that the instinct of the bird enables it to adapt itself instantaneously to varying circumstances; that in any arrangement for effecting flight by machinery--the adjustment of parts to meet sudden requirements being a matter requiring momentary thought--it is desirable, if practicable, to employ large surfaces for parachutic action, at the same time making this means of safety not an incumbrance, but an aid. The possession of instinct allows of the employment of the smallest surface in proportion to weight; the possession of forethought renders it necessary that intermittent action shall be safeguarded by large surfaces.