126 STRAINS IN THE HULL OF A SHIP AT SEA. 



DISCUSSION. 



The Chairman : — It is hardly necessary for me to mention (as I presume you all 

 know) that Mr. Howard is one of the most distinguished men in the world in regard to the 

 testing of materials. For a great many years he did all the testing with the famous machine 

 at the Watertown Arsenal, and an enormous amount of information, on which naval archi- 

 tects, engineers and all other people who use materials have depended for years, has been 

 the result of Mr. Howard's splendid work. Consequently, I feel that the Society has had an 

 unusual treat in hearing this splendid paper by such an eminent man in the profession, and 

 I hope that some of you will show your appreciation of the paper by the discussion. 



Mr. Thomas M. Cornbrooks, Member: — This ship to which Mr. Howard refers was 

 originally built for the Boston Steamship Company 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 developed any 

 irregularities. 



As confirming 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 ex- 

 perienced was at the break of the bridge just at the point where Mr. Howard made obser- 

 vations. Some ten or twelve rivets would loosen. These would be re-driven, and again after 

 two or three months they would loosen again. The bridge shear was stepped down to the 

 rail, and then, about fifteen feet further forward, the side plating was stepped down to the 

 upper deck shear strake. 



Professor C. H. Peabody, Member of Council: — 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 information 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 importance, but in a conventional manner, 

 and the results stated cannot be given as being absolute stresses to be expected in a ship at 

 any time. Here we have the strains themselves, and, in consequence, the stresses reported 

 to us from direct observation. 



The Chairman : — I wish some of our professional members would say a word. This 

 seems to me to be a very interesting and valuable paper, and I hope those members within 

 whose purview it comes, particularly, will have something to say. 



Professor H. C. Sadler Member of Council: — I am afraid I cannot add very much to 

 this discussion, but I should like to add my appreciation of the paper. Unfortunately, I have 

 not had an opportunity of reading it up to the present. One point struck me as being par- 

 ticularly interesting, and that was the confirmation of an increase in stress due to discon- 

 tinuities in the structure. Some years ago Mr. Bruhn, of Lloyd's, read a paper upon this 

 subject, in which he analyzed the effect of discontinuities in structure from a theoretical 

 standpoint, and it is very interesting to see that his conclusions have been confirmed by the 

 experiments reported in this paper. 



Another point in the paper, which I think is of particular interest, was the movement 

 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. 



