REPORT OF THE CHIEF OF ENGINEERS. OFFICE OF THE CHIEF OF ENGINEERS, Washington, D. C., October 20, 1871. SIR: I have the honor to present, for your information, the following report upon the duties of the Engineer Department during the fiscal year ending June 30, 1871: OFFICERS OF THE CORPS OF ENGINEERS. The number of officers in the Corps of Engineers at the end of the fiscal year was 100 on the active list, and six on the retired list. In addition, the corps was aided in the performance of the duties intrusted to it, by a number of civil engineers, geologists, &c. Since the last report, the corps has lost by death Major Chauncey B. Reese, brevet brigadier general United States Army; First Lieutenant William H. Chase and Brevet Second Lieutenant James B. Mackall, and one captain and two second lieutenants, by resignation; the captain, Brevet Lieutenant Colonel Peter S. Michie, having been appointed professor of natural and experimental philosophy at the Military Academy. On the 30th of June, 1871, the officers were distributed as follows: On duty in the office of the Chief of Engineers, including the Chief. On duty with boards of engineers for fortifications.. On duty with battalion of engineers.. 4 6 12 On duty, construction of fortifications. 8 On duty, survey and construction of river and harbor improvements... 23 On duty, construction of fortifications, and river and harbor improvements..... 21 On duty, survey of northern and northwestern lakes.. 6 On duty, explorations in the field west of Rocky Mountains. 2 1 On special duty. Absent sick... 1 1 Detached, on duty with generals commanding divisions, departments, &c., Light-House Establishment, Military Academy, &c.. 15 Total... 100 The officers detached were on duty as follows: Lieutenant Colonel I. C. Woodruff, engineer third and fourth lighthouse districts... 1 Major Nathaniel Michler, on staff of major general commanding Major George H. Elliot, engineer secretary to Light-House Board.. Captain Peter C. Hains, engineer fifth and sixth light-house districts. Captain David P. Heap, on staff of commanding general Department of Dakota... Captain William A. Jones, on staff of commanding general Department of the Platte... First Lieutenant Ernest H. Ruffner, on staff of commanding gen- Captain Garret J. Lydecker, First Lieutenant James C. Post, First Ι 1 1 1 1 1 1 15 The following principal civil engineers and geologists were employed on the 30th of June: General J. H. Wilson, member of board of engineers upon improvement of the Des Moines and Rock Island rapids, and improvement of the Illinois River; Clarence King, geologist in charge of geological exploration of the fortieth parallel; and Professor Wesley Newcomb, mining engineer Sutro Tunnel Commission. By legislation contained in section 6 of the act approved March 3, 1869, it is provided that there shall be no new appointments and no promotions in the Corps of Engineers until otherwise directed by law. Under the operations of this law, the strength of the Corps of Engineers has since that date become so much reduced, that the want of officers, for the performance of the varied and extensive duties imposed by law upon the Engineer Department, is becoming a serious embarrassment. It is earnestly recommended that Congress be asked to so modify the provisions of this law as to remove the prohibition of promotions and appointments in the corps. SEA-COAST AND LAKE FRONTIER DEFENSES. From the experience gained during the recent war in the attack and defense of sea-coast defenses, and from experiments made since the war, at home and abroad, upon materials in use in such defensive works, the conclusions have been arrived at which form the governing principles in determining the nature and extent of the sea-coast works we are now building. These conclusions, and the steps leading to them, have been set forth in my annual reports during the past few years, but the former may be briefly recapitulated as follows: First. To confine the new constructions to powerful barbette batteries in earth and sand, thoroughly protected by traverses and parados, and to modify existing barbette batteries so as to bring them to the necessary standard of strength and efficiency; Second. To substitute as far as practicable depressing gun carriages for those that expose the armament and cannoniers above the parapet; Third. To make liberal use of heavy mortars; Fourth. To employ torpedoes as accessories in the defense of the channel ways and approaches to the harbors; Fifth. To use obstructions and floating batteries to retain the enemy before the guns of the littoral batteries; and Sixth. To use in the batteries the most powerful guns of modern ordnance. These principles for the construction of our coast defenses have received both executive and legislative approval, and moderate appropriations for constructions in accordance with them have been made by Congress for the defensive works of some of our principal sea ports and centers of commerce. With these appropriations good progress has been made, during the past year, in the modification of existing works and the commencement of new emplacements for heavy guns and mortars. For the works along the southern seaboard, the season of active operations, since the granting of appropriations for that section, has not yet arrived, but the modifications will be carried out as far as the moderate means available will allow during the coming working season. Upon other fortifications not included in the above, the work has been confined principally to the protection of the sites, the preservation of those portions of the works in an unfinished condition, and to the modification of platforms for the introduction of heavier armaments. In the preceding no reference has been made to casemated works, and there is at present no intention on the part of the Engineer Department to recommend either the modification of existing casemates or the construction of new works of this kind. But it is important that some guns at each of our great harbors should be protected by casemate cover of some kind. What that kind should be has not yet been satisfactorily determined. To learn what maritime countries were doing in this particular, and especially the extent to which iron had been introduced into their sea-coast defenses, Colonels Barnard and Wright and Captain Michie were, by your orders, sent abroad last year. The report of this Board of Engineers, now in press, contains the results of their observations and inquiries, so far as the information gained was not of a confidential character. This information will be found valuable in devising structures for the casemate cover of guns at those sites where such cover is essential to the perfection of the system of shore defenses. Experiments have been made with King's counterpoise carriage, and are still in progress, while several designs of carriages for effecting the same purpose are under examination in the Engineer Department. There seems to be good reason to believe that a serviceable carriage for the purpose needed will soon be obtained, and in anticipation of this event the points at which such carriages should be placed in our projected works have been designated in advance. Torpedo experiments, of the character mentioned in my report of the past year, have been carried on at Willet's Point, and considerable advance has been made in the investigation of the methods of firing torpedoes and the development of the law governing explosions of various powders under water. The use of obstructions in the fairways and channels leading to our sea-ports will be indispensable in a conflict with a maritime power of any prominence, but neither these nor torpedoes can be successfully moored or managed without an intimate knowledge of the direction and veloci ties of the tidal currents peculiar to the localities. These considerations have led, during the past year, to a series of examinations in our principal harbors upon the velocity and direction of the currents, and data has thus been obtained not only useful for defensive purposes but also for commercial purposes in the improvement of the channel ways and harbors. |