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270 THE MARINE REVIEW ship to another. Such. methods, of course, led, in the majority of cases, to one of two results: either deficiency of strength, or excess of strength. For any structure erected on shore, the latter fault is not necessarily a serious one, except from the point of view of cost. On a ship, however, too much material is almost as grave an error as too little, for every ship is built to perform some _ distinct service, and, as a floating body, can carry for all purposes only the equiv- alent of the weight of water which it displaces. Every pound which goes unnecessarily into the structure of the ship itself is a dead loss to the aim or object for which the vessel is designed. Determining Longitudinal Strength The modern theory of longitudinal strength for a vessel, as based on many years of observation and ex- periments, has its origin in the simple fundamental theories of strength of beams or girders. The ship’s struc- ture as a whole is considered as a built-up girder with upper and lower flanges and connecting webs. This girder is assumed to be supported on a wave of length equal to that of the ship. The height of this wave is assumed to have various relations to its length, depending upon the magnitude of that length, but for the majority of cases this relation is taken as 1 to 20. This girder is then assumed to be supported in a manner represented by the buoyancy curve of the ship when floating on such a wave. The form of this buoy- ancy curve will, of course, vary with the position of the ship in relation to the crest and hollow of the wave, and in important strength calcula- tions it is redrawn for at least two, and sometimes as many as Six, posi- tions. The loading of the girder is represented by the loading of the ship, including its own weight, that of permanent installations, such as propelling machinery, etc, and that of the variable or useful load car- ried. By successive integrations and the use of the simple beam formula we then arrive at the figures repre- senting stresses and strains in the theoretical girder. Some experiments have been made from time to time, notably those of Biles in 1903, to check the accuracy of the results ‘obtained by this method, but, due to the cost and magnitude of such ex- periments, there -have never’ been collected sufficient data to enable us to say how accurately these results do represent the actual stresses in the ship in service. Accordingly, we are still largely dependent on com- paring the figures obtained by this method for the new ship with those obtained by the same method for previous ships that have shown ade- quate strength in service. Possibly due to the fact that our standard wave. is not so steep as waves having the length of short ships, and steeper than waves having the length of long ships, it seems to have been thoroughly established by experience that, with the method out- lined above, it is safe to allow larger stresses in large and long ships than Won Honors at School “The career of Admiral Taylor must be a source of intense pride and an inspiration to every Amer- ican; for his achievements are such ° as to place him in the foremost rank of naval engineers of any country and of any time. © “He was born March 4, 1864, Louisa county, Virginia, as a Hneal descendant of distinguished soldiers and statesmen of the Revolutionary period. His early education and preparation for college he acquired by home instruction and study, en- tering the Randolph-Macon college in Virginia as a mere boy of 13. On completing. the 4-year course im this institution in 1884, he won an appointment as cadet engineer in the naval academy at Annapolis, attaining second place among 130 competitors from the country-at- large. He graduated in 1885 at the head of his class, and with the highest percentage of marks for the entire course ever attained by any graduate of the academy before or since that date. In the fall of the same year he was ordered to Lon- don to enter a 3-year post-graduate course in naval architecture at the Royal Naval college at Greenwich. At the end of the first year he had made such a high record in scholar- ship that the secretary of the navy appointed him an assistant con- structor with the rank of junior lieutenant, and upon the completion of the entire course he established a record for percentage of marks which has never been equaled by any graduate of the college, either before or since that time.’—From the presentation address. in short and small ones. If, for in- stance, we find that by this method a small vessel in service shows sat- isfactory results when her figured standard stress is, say, six tons in compression and eight tons in ten- sion, and shows indication of weak- ness if these figures are materially exceeded, we would find that also in service a very large and long ship would show no signs of weakness with calculated stresses as high as 10 tons in compression and 12 tons in tension. This principle appears to have been acted upon, though the scientific principles underlying it were not fully understood, even in the August, 1917 early days of iron shipbuilding. This was brought out about 50 years ago, when our modern methods of figur- ing ‘strength were first applied to ships built in accordance with the then existing rules of classification societies, with the result that the large ships of that day were found to have indicated stresses in extreme cases nearly five times as great as those found in small ships. There are, of course, a very large number of strength problems in- volved logically in ships themselves, and therefore particularly within the province of naval architecture, but these are, after all, secondary when compared with the problem of the strength of the main structure. The Question of Stability Turning now to stability, which is the measure of the ability of a ship to remain upright or to return to the upright when inclined by an external force usually impressed by varying conditions of water surface, we find that the full and exact treatment of this branch is of quite modern origin. In the earliest day adequate stability was largely dependent on carrying ballast, and the amount and location of such ballast was determined by trial. In other words, except by fol- lowing more or less closely the model of a previous vessel, there. was no means of determining in advance whether a proposed design would re- sult in a satisfactory stability condi- tion. About the middle of the eighteenth century the French mathematician, Bouguer, made a long step in devel- oping the science of stability by de- veloping the concept of the meta- center. In mathematical language, the metacenter is the center of curv- ature of the locus of the center of buoyancy of the vessel as it is in- clined. As a _ practical proposition the metacenter is the limit above which we cannot locate the center of gravity of the ship without having her initially unstable and unable to remain upright. The position in space of this imaginary point depends upon the geometrical form and the dimen- sions of the ship. Perhaps a homely illustration may clarify the matter. If you take an ordinary rocking chair and attach a weight to it in such a manner that the center of gravity of the chair and. the weight is above the center of curvature of the rocker, the chair will not stay put and will loll over and capsize. If the center of gravity is materially below the center of curvature of the rocker, which is the case when one sits in an ordinary rocking chair, the chair will remain in a fixed position; if the \