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Active Gyro Stabilizer Elmer A. Sperry read his paper on "Some Graphic Studies of the Active Gyro Stabilizer", at the December meet- ing of the Society of Naval Architects and Marine Engineers. This work was undertaken to verify some observations made in connec- tion with the sea trials of the active gyro stabilizer, which time did not permit of reproducing, and also to pursue some investigations further than was possible at sea, where it was felt that the sea characteristics were only at best roughly estimated, and where, for the purposes of checking, their recurrence could not be secured. Again, a number of questions arose upon which more light was needed as to the exact behavior of the active gyro stabilizer, for instance, under widely varying phase relations of sea and ship, and also under widely vary- _ing conditions as to wave slope, gen- eral sea intensity, etc. In this way we have been enabled to verify, under conditions of much more extended ob- servation, just what happens when the stabilizing capacity of the gyros is approached, exceeded and also far sur- passed, and thus verify the results at sea. Another important point is that with the new stabilizer no special problems whatever are introduced by the con- dition of synchronism or, in fact, any harmonic relation between the periods of the sea and ship. Again, no small interest centers about the fact that with the active stabilizer no phenomena exists cor- responding to the marked falling off in stabilizing capacity of damping tanks each side of the synchronous condition, nor is any phase relation possible between the waves and ship at which the active stabilizer is found to have the slightest tendency to add anything whatever to either the ampli- tude or the Boeri. of roll as do tanks, | It has been ascertained, also, that no alterations or adjustments of the gyro is necessary to fit changes in period of either sea or ship. The plant was found to work with equal reliability throughout the whole gamut of phase relation of wave slope and also under conditions of forced roll- ing. Under the head of "Forced Rolling", that is, when the ship leaves her nat- ural period and takes up the period of the sea, it is believed that never before has this interesting phenomena been studied where, for all practical purposes, the ship has been completely Stabsized for all frequencies, and it is THE MARINE REVIEW believed that an advance has been made in knowledge of forced rolling, and the conditions under which it in- variably takes place. The stabilizing efficiencies of the active model have been determined, confirming the high efficiencies ob- served in operating a full-sized plant at sea. The unique action and dependa- bility of the journals have also re- ceived confirmation. The space and weight requirements, smallness of the power required, and the very low maximum stresses in the plant as well as in the ship in the vicinity of the plant have also received a valuable check. The general reliability and simplic- ity of the system of velocity control has also received confirmation. Mr. Sperry explained his paper at length, but it is impossible to re- port it without reference to the diagrams which, however will be given in- -the dransactions. During 'the course of his remarks Mr. Sperry said that at certain points in the phase relation between ships and wave anti- rolling tanks are positively danger- ous...In reply to a question.by H. C. Higgins: as to how much _ space the stabilizer occupies he replied that it occupied only a small percentage of the space occupied by the tanks and weighed a little under 1 per cent of the ship's displacement. In reply to a question by E. L. M. Sivard on the influence of the stabilizer on the stresses of the ship he replied that there was virtually no stress. Handling Shells With Coaling Capstans Between three and four days time was saved in getting the battleship New York away from the navy yard in Brooklyn, when she was preparing to hurry off to Vera Cruz recently, by a novel use made of her deck capstans and coaling rig in getting aboard her ammunition for the 14- in. guns. This was possible because of the new control device invented by the Lidgerwood Mfg. Co. who built and installed the capstans. A set of deck capstans for independent coaling is a customary provision on battleships. They are arranged along both sides of the ship as in the case of the New York and are used to handle whip lines which run through blocks at the ends of spars footed near the rails and extending at an angle outboard so that the falls drop clear of the ship's side. The spars are footed a little out of line with the capstans so that they naturally ' 1,400 Ibs. June, 1914 swing around and bring their loads over the deck. The swinging of the spar is controlled by hand with lines running to the tops of the spars. The capstans are driven by gears on two line shafts which run under the deck, one along each side of the ship. These _ shafts special twin engines.- The line shafts run constantly when any of the capstans are in service. The cap- stans are so built that they can be picked up bodily and removed when the ship is cleared for action leaving the deck flush. Ordinarily they are arranged to be individually discon- nected from the gears by means of a separate hand wheel for each so that - any one of them can be. stopped to prevent accident or for other pur- poses. When the installation of the coaling capstans for the New York was being considered the navy de- partment. required a more efficient method of control. The Lidgerwood Mfg. Co. undertook to meet this de- mand. The capstans on the New York are controlled by a foot pedal be- side the foot of the capstan, <A slight pressure of the foot instantly and positively connects the gears and a similar light pressure on a catch beside the pedal'releases the button and automatically puts the capstan into action. The real power for the connecting and disconnecting actions is secured from the line shaft by a very simple and ingenious mechanism. This facility in connecting and dis- connecting was what made it possible for the coaling apparatus of the New York to be used with safety in taking aboard such sensitive and dangerous ammunition as 14-in. shells. This work was done without accident and with perfect satisfaction to the naval authorities, although the shells weigh and the coaling apparatus is intended for handling 800 lb. loads. At a recent hearing to determine the advisability of using concrete for the immense new dry dock, forming part of Boston's port photographs of reinforced concrete piers, built by the Aberthaw Con- struction Co., in 1909, formed one of the determining features. These pho- tographs showed that with proper mix and treatment the combined chemical and frost action of sea _water could be neutralized even when the material was subjected to alter- nate immersion in the water and exX- posure to the air. The decision was to build of reinforced concrete with wearing surfaces or altars of granite. are driven py. ee a development,