Iron-testing machine.-Commander Beardslee's impact hammer. Iron which, when manufactured, is, during its use, to be subjected to sudden transverse strains should possess in the greatest degree the quality of resilience or power of resisting shocks. A great tensile strength is seldom accompanied by a proportionate transverse strength or resilience. The strain to which a chain-cable is most liable to yield is that of a surge or sudden strain; iron suitable for chain-cables should have the power of resisting these strains. The testing machines in general use test only the power of the metal to resist steady strains of tension and torsion. This machine has been contrived to ascertain the power of iron rods to resist shocks. The following is a description, accompanied by Figs. 1, 2, and 3: DESCRIPTION. A cast-iron hammer having a wedge-shaped impact surface upon its lower side (Fig. 2) is made to traverse two perpendicular iron rods of, say, 24 inches diameter, and from 30 to 50 feet in length, which pass through holes in the body of the hammer, as shown at a (Fig. 1). The hammer may be of any weight, a convenient one being 100 pounds. A traveler of wood or metal, fitted with a pair of hooks which can be opened or closed by pulling up a cord (h) attached to them, is placed upon the rods above the hammer, as shown at e (Fig. 1). At the foot of the rods, they passing through it, as shown at i, a heavy cast-iron block with a cylindrical opening (k) 8 inches in diameter is fitted; the specimen of iron to be tested (j) is placed across this circular hole, the hammer resting upon the box which surrounds the anvil, to prevent accidents, as shown by dotted lines (0), and supported by a chock (p). A common purchase (shown at f), through which a hoisting rope is led to the windlass (g), is secured to the upper portion of the framework. At the side of one of the rods an upright, marked plainly to feet and inches (1), is secured. Should it be necessary to carry the rods through a flooring, as shown at x (Fig. 1). a slight projection on the upper surface of the traveler (shown at m) is fitted to come in contact with and operate a light rod which has on its lower end a pointer (n). To use the machine, the traveler is lowered until the clip-hooks clasp a projection on top of the hammer; the latter is then hoisted to the desired height, the lower edge of the hammer being brought in line with the figure on the measuring rod. Should the hammer be hoisted out of sight, through a floor, the marker (n) will indicate its height. When at the proper height, the tripping-line (h) is pulled, opening the hooks, and releasing the hammer, which falls, striking the specimen (j) in the center a blow whose force can be measured, and which is dependent upon the gravity of the location, and slightly decreased by the friction. A coarse and brittle iron will break short at a moderate blow from this hammer; a tough and strong iron will resist its utmost power. The weight of the hammer can be increased at will, by the addition of lead weights. An iron which exhibits good results when tested in this manner, and also possesses great power of resisting steady strains of tension, is suitable for chain cables; one that does not, is utterly unsuitable for the purpose. To estimate the force of blow delivered by the impact-hammer machine, use the following formula: wv2 F, in which 2g wweight of hammer in pounds, vits velocity in feet, g=gravity (at Washington 32.153), F= force in foot-pounds. The formula is derived from the empirical law, as follows: h=gt2, Multiply both by g, and you have ghg2t2, or 2ghg2t2, or √2gh=gt, which is practically found to equal v: hence, is the effect of one pound falling one foot in one second. The force F of any number of pounds w, falling one foot in one second, is w times as great, or gt2 deduce, as before, √2gh=gt = v, or for a height of 30 feet, or velocity of hammer at instant of striking when dropped 30 feet (the friction not being estimated). The force is derived from the formula To make a table giving foot-pounds force for each foot of hoist: 2x32.153×a×100 in which a varies for each foot; cancel common factors, and the foot-pound force is at each height: = the height multiplied by 100; thus, 30 feet drop = 3,000 pounds. 26. Steam Steering Machine (Sickles's patent). [Extract from a report of U. S. naval officers on the trial of this machine.] This apparatus was temporarily applied to the U. S. iron-clad Roanoke, for the reason that this vessel not only required greater power to move her large rudder, but also presented the difficulty of being efficiently steered from the pilot-house above her turret. The steering machine consists of two cylinders of 24 inches diameter and 12 inches stroke, placed at right angles and connected directly to the steering drum. It was placed in the lower chamber of the center turret, occupying a space of 8 feet 11 incle by 5 feet 6 inches, with a height over all of 5 feet 11 inches, and, although of same general principle as has been heretofore applied, yet the details of this arrangement have been so perfected as to gain all requisites of rapid steering from any part of the vessel without interfering with the ordinary internal arrangements of a vessel-of-war. The machine itself is to be placed below the water and entirely protected from shot, the only parts exposed being the ordinary tiller ropes and the small line leading to the deck or pilot-house. For use in iron-clads, where space is of so much importance, the dimensions above given can be materially reduced. With the ordinary hand-steering wheel, it took the full force of two men (all that the pilot-house could conveniently contain) over to minutes two move the rudder from its extreme positions of starboard and port, and requiring twenty-six turns of the wheel. With the steam machine, one man could easily move the rudder the same distance in three seconds with three and one-half revolutions of the wheel. The steering cords were led to the pilot-house above the forward turret, and leaders provided by which the vessel could be steered from any part of the vessel deemed most convenient. The steam-steering arrangements were applied to the tiller, entirely independent of the hand-steering gear, so that either one was available for use without interfering with the other. An indicator is fitted with the machine, so that the helmsman can at any time ascertain the position of the rudder, and the engine is so designed as not to require either skilled mechanical labor in its operation or care, as it can be worked by any seaman in the same manner and more readily than the ordinary steering wheel. It is at all times ready for use when steam is raised, as by the peculiar arrangements of valves it is not necessary to first free the machine from condensed water, or prepare it for service, as is necessary in the Cameron steam-engine. In the steam-pipes is fitted a regulating valve, so as to retain the power of the engine with the same and varying pressure of steam; that used on this trial averaging about 17 pounds per square inch. The valves of the engine are so designed as to hold the rudder at any desired angle, and also where "hard over," to slightly yield for the instant to any sudden shocks or strains that may endanger the safety of the rudder. The durability of the various details of the steering-gear was clearly shown, as the apparatus was kept in use for four consecutive days, and subjected to the severest trial to test its strength. It is certain in its action, and so little labor is required from the man at the wheel that he can be more careful in his attention to the course of the vessel, and act with greater promptness in every emergency, and more securely guard against accident from collision. In case of a vessel-of-war in action, this most important point cannot be overrated, as quickness of maneuver in making the attack, as well as facility in avoiding the enemy, either from the ram or torpedo, is one of the most essential features of a manof-war. 27. Life Boat, or "Balsa," designed by Commodore Daniel Ammen, U. S. Navy. The original of this life boat, or balsa, was designed and built on board the U. S. steamer Mohican, in 1865, by the commanding officer of that vessel, now Commodore Daniel Ammen, U. S. Navy. It is not patent d, and is built at the U. S. Navy-yards for use on board of vesselsof-war. It has great buoyancy in proportion to its weight, is constructed at small cost, easily kept in repair, and cannot swamp. If injured by running upon rocks, a patch of tarred cotton cloth placed under a thin sheet of lead, and tacked over the hole, makes the boat practically as serviceable as ever. It sails well, is pulled with ease, and can be handled with great facility. Modified for river use and in bays, it would offer an inexpensive means of floating and carrying a large number of persons, should the vessel supplied with them be lost by fire or otherwise; and in emigrant ships they could be used as water-casks, and speedily emptied if required for use as life boats. EXHIBITS OF ARTICLES GENERALLY USED IN SIAM, AND OF SAMPLES OF TRADE OF SIAMESE ORIGIN, PREPARED BY ORDER OF HIS MAJESTY THE KING OF SIAM, AND PRESENTED BY HIS MAJESTY TO THE UNITED STATES OF AMERICA AS A SOUVENIR FROM THE KINGDOM OF SIAM. CORRESPONDENCE. NAVY DEPARTMENT, Washington, September 30, 1876. SIR: The Department incloses for your information a copy of a dispatch from RearAdmiral William Reynolds, commanding Asiatic Station, dated June 26, 1876, also a copy of its inclosure from the minister of foreign affairs of Siam, in relation to a collection of articles from that Government to the Centennial Exhibition at Philadelphia. Also inclosed is an inventory of the articles, which you will please endeavor to have translated; after which you will return it to this Department to be returned to the Department of State. The articles referred to have arrived at San Francisco, and are on the way to Philadelphia. Very respectfully, I. C. HOWELL, Acting Secretary of the Nary. U.S. Navy, Philadelphia, Pa. Rear-Admiral THORNTON A. JENKINS, No. 59.] FLAG-SHIP TENNESSEE, SECOND RATE, SIR: I inclose herewith a copy of a letter addressed to me by the minister of foreign affairs of Siam, and also of a letter from the same personage to the Secretary of State of the United States, inclosed therein, and received by the last mail from Hong-Kong. The list of articles did not accompany the letter. Commander Matthews reports from Hong-Kong, June 14, that the Siamese Curios could not go in the Alaska, then about to leave that port, as she was full of freight, but would go by next steamer, the Belgic, to leave July 1, for San Francisco. They should arrive in Philadelphia during the first of August. I am, very respectfully, WILLIAM REYNOLDS, Rear Admiral Commanding U. S. Naval Force, Asiatic Station. Hon. GEORGE M. ROBESON, |