signed by Mr. J. M. Stevens, of Boston, by whom it was placed at the Exhibition. Steam siren. The general character of the instrument may be described as follows: Suppose a drum of short axis, into one head of which is inserted a steam-pipe connected with a locomotive boiler, while the other end is provided with triangular orifices through which the steam is at brief intervals allowed to enter. Immediately before this head, and in close contact with it, is a disk provided with corresponding radial slits. This disk revolves 2,000 times a minute. By this arrangement at every complete revolution of the disk the orifices in the head of the drum are opened and shut with great rapidity, thus producing a series of rapid impulses of steam. This steam issues through the smaller orifice of a trumpet immediately in front of the revolving disk. The impulses are of such intensity and rapidity as to produce a sound of great magnitude and penetrating power. The siren is attached to a horizontal cylindrical tubular (locomotive) boiler, with a pressure of from 50 to 150 pounds on the square inch. A small engine is attached for feeding it and for rotating the disk, the latter being effected by means of a band passing over pulleys of suitable relative dimensions. The machine as exhibited was complete in all its parts as adapted for steam, cold or hot air, or other gases under pressure. Siren blown by compressed air.-A 12-horse power engine operates this siren. At one time when fires were not even lighted on this caloric engine, orders were given, and in seven minutes the fog-horn was blowing its regular blasts at intervals. Courtenay's automatic signal-buoy.-A model of this was exhibited in September. It consists of a large can, a shell, to which a tube 32 or more feet in length is attached. This tube passes through the buoy, and is furnished with a diaphragm through which pass three smaller tubes. One of these tubes is open at both ends, the upper end being so placed that any air passing through it will act upon the whistle placed upon the top of the buoy. The other tubes are open at the top, and at the bottom are fitted with ball valves, which allow air to pass down, but prevent it from passing up. If now the buoy should remain stationary and the level of the water rise and fall around it, the following would be its action: As the water fell in the large tube, air would rush in through the smaller tubes, the valves being arranged to allow this. As the water rose again the air between the diaphragm and the water level would be compressed, and as the valves closed the only exit would be the tube connected with the whistle. It will thus be seen that the action of the apparatus itself is of the simplest character. These buoys may be moored in a sufficient depth of water. Each buoy is provided with a sort of wing or rudder, which keeps it in proper position. UNITED STATES COAST SURVEY. At the beginning of the present century extensive geodetic surveys were going on in different parts of Europe, undertaken as well for their indirect as for their direct results, and geodesy was rapidly assuming a scientific and practical form. The example was not unheeded by the United States. The requirements of commerce pointed to a survey of the coast as the measure of immediate importance, and through the intelligence and influence of its distinguished advocates the work at the very outset was organized upon the most approved methods known to geodetic science. Toward the close of 1805 Ferdinand R. Hassler, a native of Switzerland, arrived in the United States in search of a permanent home. He had been employed in the triangulation of the canton of Berne, and his valuable experience, combined with high scientific attainments, early attracted the attention and won the consideration of those who, fortunately, were scientists themselves, and at the same time prompt to take up any plan that would advance the interests and credit of the country. Among these Dr. Robert Patterson, president of the American Philosophical Society, and Albert Gallatin, then Secretary of the Treasury, stood pre-eminent. The law authorizing the survey of the coast was passed February 10, 1807, upon the recommendation of Thomas Jefferson, then President of the United States, and the plan adopted for its execution was the one proposed and previously foreshadowed by Mr. Hassler. In 1811 Mr. Hassler proceeded to England to have the necessary instruments made according to designs prepared by him; was detained there during the war with Great Britain; returned in 1815; and in August, 1816, was formally appointed Superintendent of the Survey. Operations were at once commenced on a limited scale, and were vigorously prosecuted until April, 1818. For a considerable period after that date appropriations ceased, but public conviction in regard to the utility of the work permanently deepened during the suspension of the survey. In July, 1832, Congress, at the repeated solicitation of the Hon. Samuel L. Southard, Secretary of the Navy, and of others interested in the development of the coast and harbors, revived the act of 1807, and Mr. Hassler was reinstated as Superintendent. From 1832 to 1836, the survey was under the control of the Navy Department. In the latter year the charge was reassigned to the Treasury Department, and so remains. 8 CEN, pt. 2 113 |