ENGINEER DEPARTMENT, UNITED STATES ARMY. REPORT ON THE EFFECTS OF THE SEA-WATER AND EXPOSURE UPON THE IRON-PILE SHAFTS OF THE BRANDYWINE-SHOAL LIGHT-HOUSE. BY JOHN D. KURTZ, IJEUT. COLONEL OF ENGINEERS, BVT. COLONEL U. 8. A.; OFFICE OF THE CHIEF OF ENGINEERS, Washington, D. C., December 17, 1873. SIR: Lieut. Col. J. D. Kurtz, Corps of Engineers, in charge of the construction of the iron-pile landing-pier at the Delaware Breakwater Harbor, has prepared a report on the effects of the sea-water and exposure upon the metal subjected to their influences at that work. As this is a matter of interest to engineers, I have respectfully to recommend that the report be printed at the Government Printing Office, and that five hundred copies be furnished on requisition from this office. Very respectfully, your obedient servant, Hon. W. W. BELKNAP, Approved : Secretary of War. A. A. HUMPHREYS, Brig. Gen. and Chief of Engineers. BY ORDER OF THE SECRETARY OF WAR: H. T. CROSBY, Chief Clerk. REPORT. UNITED STATES ENGINEER OFFICE, Philadelphia, Pa., December 3, 1873. GENERAL: Since I have been on duty here, it has been several times proposed by the officers of engineers on light-house duty to examine the iron-pile shafts of the Brandywine light-house, for the purpose of ascertaining the effects of the sea-water and exposure upon the metal subjected to those influences. The construction of the iron-pile landing-pier at the Delaware Breakwater Harbor, which I have in charge, has caused this question to become one of great interest to me, and I therefore made an arrangement with Lieut. Col. W. F. Raynolds, Corps of Engineers, light-house engineer of this district, by which he supplied a steam-tender and crew, and I furnished a party from the pier, with diver, suit, and necessary apparatus to make the examination. Capt. M. R. Brown, Corps of Engineers, in immediate charge of the construction of the pier, took personal charge of the party and directed the investigation. The Brandywine light-house is within the mouth of Delaware Bay, and nearly nine miles from Cape May light, from which it bears about northwest by west. The piles which support the light-house were put down in 1848, and those of the ice-fender system about it in 1849, except the outer row (38), placed in 1856 and 1857. The light-house piles are hammered iron; the fender-piles, rolled iron. The subject is one of general interest to engineers engaged upon submarine works, and it is of special importance to the Light-House Establishment, which is engaging so largely in the use of iron piles for the substructures of light-houses. Much discussion has been given to the question of the endurance of iron exposed to sea-water; but I have not seen any account of actual |