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'March, NE ay ee a a IS TE ER RE SD Fo en een ae Ney LTS 1914 various parts of the ship caused either by cargo or the revolution of the en- gines. On the trip to Colon with a full cargo the cargo strains exceeded those caused by propeller revolutions but the reverse was true on the re- turn trip with a light cargo. It is im- possible to give an account of Mr. Howard's discussion, as it was illus- trated by lantern slides, but these will be later incorporated in the trans- actions. The Chairman:--It is hardly neces- sary for me to mention it, I presume you all know that Mr. Howard is one of the most distinguished men in the world in regard to the testing of ma- terials. As you probably know, for a great many years he did all the testing with the famous machines at the Wat- ertown Arsenal, and the enormous amount of information on which all naval architects and all other people who use materials have worked for years, has been the result of Mr. Howard's. splendid work. Conse- quently, I feel that the society has had an unusual treat in having this splendid paper by such an eminent . man in the profession, and I hope that some of you will show your ap- preciation of the paper by the dis- cussion. Loosening of Rivets Ernest I. Cornbrooks:--This type of ship, to which Mr. Howard refers, was originally built for the Boston Steamship Co., of Boston, and as those were the first large ships. built by our company, I kept in touch with them for years to see if they devel- oped any irregularities. As confirm- ing what Mr. Howard said in regard to the strains on the rail near the bridge, I remember that Mr. Wiley, superintendent-engineer wrote me that the only trouble they experienced was at the break of the bridge just at the point where Mr. Howard made observations. Some ten or twelve rivets would loosen. These 'would be redriven, and again after two or three months, they would loosen again. C. H. Peabody:--I think that it is quite impossible to overestimate the importance of investigations of this sort, and it is also difficult to under- stand how so much information can be given in so short a space. This is an investigation giving us informa- tion in regard to. a subject of the very highest importance, about which, so far as I am aware, we have not had direct information. The ordinary calculations for strength of ship are made habitually for ships of import- ance, and always should be made, but in the manner in which they are years ago. Mr, THE MARINE REVIEW habitually made their relative appli- cations and the results stated cannot be given at all as being absolute stresses to be expected in a ship at any time. Here we have the strains and in consequence the stresses re- ported to us. Herbert C. Sadler:--I am afraid I cannot add very much to this discus- sion, but I. should like to add my appreciation of the paper. Unfortu- nately, I have not had an opportu- nity to read it at present. One point struck me as being particularly inter- esting, and that was the conforma- tion of an increase in stress due to discontinuities in the structure. Some Broom, of Lloyds, read a paper upon this subject, in which he analyzed the effect of dis- continuities in structure from a theo- retical standpoint, and it is very in- teresting to see that his conclusions have been confirmed by the experi- ments reported in this paper. Another point in the paper, which I think is of particular interest, was the move- ment of the joint as compared with the movement of the solid plate. It seems rather remarkable, really, that the lap joint should move three to four times as much as the center of the plate. I think that it is a thing which we probably had not realized. before'. and, it. 4s, perhaps; a little hard to understand. Elmer A. Sperry:--I do not think Mr. Howard should feel that a failure to discuss this paper is any indication of a want of appreciation of its value. IT think it is one of the most remark- able papers we have had in a long time. The stresses on the deck plates are of rather a peculiar nature, and I think there is one point that might shed some light on these stresses, especially the marginal stresses as compared with the stresses at mid- ships, as shown by the diagram. Tests at Sea Last year, when we were running some tests at sea, some of the naval engineers tried to determine the stresses on the beams and on the deck structure, .due to our attempts to stabilize the work, and I can appre- ciate the wonderful work and _ the meaning of some of these results. There, however, seems to me to be one point that might be -overlooked, and that is this--if we take a tube, we understand that a long tube is a very stable structure, with reference to torque strength. At one end there is very little spring, and as between that end and a remote end there is quite a heavy torque strain. Suppose you take a cylinder and shave it oD down horizontally, or saw it in two, so we have a gutter, now can any of you imagine what the torque value of that gutter is as compared with the torque value of the tube out of which the gutter was made? Calculations show that it is only 1/3600. Now, then, what is a ship? A ship is a gut- ter with a deck on it, and we found, by giving close observations, that a ship has a quite considerable warp, especially a ship built on the plan of a torpedo boat destroyer, long and slender, and the plate is probably at the mean thickness consistent with safety. Now, then, as you analyze these torque strains, which always come in any rough weather, you will find that the marginal portions of the deck are the portions which must re- ceive and sustain this strain, and as the one thing which lends stability longitudinally, torquewise to the struc- ture, as a whole, I think this should not be neglected. Affected by Deck Temperature Francis T. Bowles:--I suggest that Mr. Howard tell us whether this ap- 'paratus of his has been used on other structures to determine live load, and if so, where; in other words, give us some idea of the reliability of the in- strument and how he came to make this test on this vessel, and whether he is at liberty to make it on other vessels. Francis B. Smith:--I ask Mr. How- ard if he noted at the time. the boat took on cargo, if the draft of a vessel was affected in the march forward and aft by the different temperatures _ of the deck. We have reports of that kind on our ships quite frequently. We are in the lake trade. When our boats load at the head of Lake Su- perior and go down to the Sault Ca- nal, where the draft is limited by the draft of water in the locks, they some- times claim that the ship is drawing as much as two or three inches more than she would if the temperature of the sun did not have so much effect on the decks, and I would like to ask Mr. Howard if he noted that. James E. Howard:--In regard to the features which led up to making these tests, I will say that for some time I had been engaged on the ex- amination of engineering structures, railway bridges, buildings, pavements and strain gauge observations have been the means by which the informa- tion was acquired. In this city ob- servations have been made on the Bankers Trust building, a limited number on the Woolworth building, on the main columns. The Missouri river bridge, at Kansas City, affords