comes. One-half of the other diameter has an arbitrary scale of miles of wind marked on it. Part of one semicircumference of this disk is graduated into divisions representing degrees of elevation and parts of degrees. These divisions and the scale representing miles of wind depend on each other. Curved lines on the disk are lines of uniform lateral deviation in minutes of azimuth. A short arm rotates about the center of the disk and independently of it. It has a scale of miles of wind corresponding to that previously referred to. Mounted on this arm by means of a sliding block and a hollow screw with a shoulder, serving as a pivot, is a cross-arm. Both the long and short branch of this cross-arm has a scale of miles of wind the same as those previously referred to. On the short branch this scale is marked on the metal; on the long branch it is marked on one side of a boxwood ruler of triangular cross section; the other side of this ruler has a scale for values of '; the ruler slides along the long branch of the cross-arm. δ The long branch has on its surface another graduation, which is one of minutes of elevation. The minutes of azimuth correction are therefore read on the curved lines of the disk; the minutes of elevation correction are read on the long arm. OPERATIONS. To divide the wind into its components: (1) Set arrow at azimuth of wind. (2) Set sliding block on radial arm at the velocity of wind. (3) Set radial arm at the azimuth of target; bring the cross-arm so that its long branch will be parallel to the arrow diameter. Then read on the left side of boxwood scale the longitudinal component where the scale is cut by the lateral diameter and read on the short branch the lateral component where that branch is cut by the arrow diameter. The sign + is indicated by the semicircle in which the 0 of the scale lies. The principle upon which this resolution is based is practically the graphical method of obtaining rectangular components. The angle between the direction of the wind and the direction of the target is graphically represented, and the force of the wind is so represented on the radial arm. AUTOMATIC ADDITION. The boxwood scale is set so that the reading shall be on the edge δ passing through the center of the cross-arm pivot. By this means the atmospheric effect is added without further action. The 0 of the lateral scale is set to the left of the pivot enough to allow for drift. CONVERSION TO MINUTES. (1) Of azimuth. Set radial arm at the gun elevation. Under the direction component number on this arm read the disk number, which is minutes of azimuth. (2) At the elevation component number set the sliding block and rotate on its pivot the cross-arm until the long branch reads the same number on the diameter graduation. Here read on the long branch the minutes of elevation correction. (1) Set for 1. ORDER OF OPERATION. (2) Set for wind direction and velocity. These are done in advance. (3) Set radial arm at azimuth of target and read components. (4) Set radial arm at gun elevation and read direction correction. (5) Set sliding block at elevation component and read elevation correction. ARMY BUILDING, New York City, August 14, 1896. SIR: The Board on the Regulation of Seacoast Artillery Fire, constituted by Special Orders, No. 273, Headquarters of the Army, AdjutantGeneral's Office, Washington, D. C., November 20, 1894, respectfully submits herewith its progress report for 1895–96. As most of the work done by the board during this period has been made the subject of special reports to your Board, it is deemed only necessary to mention the reports by name. The most important of these reports is the one of May 27, giving a proposed system of "fire control and direction" for the United States seacoast artillery service. This we understand was approved by your Board and has been directed to be tried at three artillery posts. Also that a board has been constituted to formulate regulations and tactics based on this proposed system. The other reports, in order of date, are: October 18, 1895.-"Printing telegraph" system of the Consolidated Telegraph and News Company of New York City. April 13, 1896.-Report of "competitive test" of the relocator, devised by First Lieut. William C. Rafferty, First Artillery; and the converter board, devised by First Lieut. E. A. Millar, Third Artillery. April 20, 1896.—"System of plotting shots and directing the fire of batteries at moving targets," by First Lieut. E. M. Weaver, Second Artillery. April 25, 1896 (Wrapper indorsement).-Returning papers relating to electrical device for automatic plotting, by First Lient. D. D. Johnson, Fifth Artillery. April 25, 1896.-Partial report on "system of range and position finding and converter board," devised by First Lieut. C. L. Best, jr., First Artillery. May 15, 1896.-"Target indicator," devised by First Lieut. Arthur Murray, First Artillery. May 19, 1896.-"Improvement in breech sights for aiming at moving targets," by First Lieut. Charles W. Hobbs, Third Artillery. May 27, 1896.-Table of "directions and distances," with plot of triangulation at the Narrows, New York Harbor. July 13, 1896.-"Plan for signaling azimuths and ranges," devised by Lieut. Bradley A. Fiske, United States Navy. August 14, 1896.-Report on competitive trial of the slide rule devised by First Lieut. E. A. Millar, Third Artillery; and the deviation index, devised by First Lieut. W. C. Rafferty, First Artillery. The board has had no experience with modern artillery and, until the results of this year's target practice by artillery troops are known, prefers to make no suggestions or recommendations as to guns, carriages, platforms, or accessories which might properly come under the head of "fire control and direction." The two systems of telephones-the Bell long-distance and the Colvin-are undergoing a thorough and exhaustive test. The Colvin system is being tested through the courtesy of the Interior Telephone Company, of New York City, at no expense to the Government other than the necessary battery power (not to exceed $35). The Bell long-distance telephones, made as nearly as at present possible to conform with service requirements, were placed at our disposal through the courtesy of Messrs. J. J. Carty and U. N. Bethel, Metropolitan Telephone Company, New York City, at no expense to the Government. As we have already stated in previous reports, we consider the subject of "communications" to be of vital importance. No matter what system may be adopted, the wiring will be practically the same, and as this can be put in at the outset at so much less cost than when the batteries are completed, we strongly urge the immediate consideration of this question for works in course of construction or to be constructed. The test of the telephones and telegraph typewriter should be continued. The board still has under consideration the various elevation-indicating devices submitted, but it is not prepared to make a definite report on any one. The RECORDER, HENRY L. HARRIS, First Lieutenant First Artillery, President. W. C. RAFFERTY, First Lieutenant First Artillery, Member. First Lieutenant Second Artillery, Recorder. Board of Ordnance and Fortification, Washington, D. C. |