124 AN ANALYSIS OF TESTS OE WATER-TIGHT BULKHEADS. 



to say that we are to be congratulated on receiving a paper of so much importance 

 and value. 



I want to ask a question concerning a statement in the middle of page 91 to 

 the effect that "In practically all cases the observed curve of deflection of the 

 stiffeners, tests Nos. i to 6, corresponded fairly with the curve calculated under the 

 assumption that the stiffeners were fairly supported at the apices of the brackets, 

 etc." I wish to ask whether, in Professor Hovgaard's opinion, this may not be 

 in part due to the fact that the stiffeners are not adequately secured at the neutral 

 axis, because longitudinal slipping would produce an effect like that due to insuffi- 

 cient fastening of the ends of the stiffeners. 



I desire, not as a criticism of this paper, but on general principles, to object 

 to the use of the word "stiffeners" in connection with a discussion of the strength 

 of bulkheads. Though I appreciate that there is difficulty in changing an ac- 

 cepted technical name, in this case I believe the use of the term " stiffeners " has led 

 to losses of ships that might now be afloat had the designers and inspectors of 

 those ships appreciated what this paper shows, namely, that the framing of the 

 bulkhead is in a sense the bulkhead ; the plating is only a water-excluding membrane. 

 The use of the word like "stiffeners" infers that the plating of the bulkhead should 

 be capable of excluding water and that it needs only stiffening to enable it to do so. 



Professor Hovgaard: — In answer to Professor Peabody's question I would 

 say that I consider the fact that the double stiffeners behaved as if free to turn 

 about the apices of their brackets as largely accidental, and without any deeper 

 significance. It simply shows that stiffeners so constructed deflect more than 

 might be expected if regard is had to their bracketing, and it shows in particular, 

 that such stiffeners are less efficient than single stiffeners. If the riveting along 

 the neutral axis had been more efficient, if, for instance, there had been two closely 

 spaced lines of rivets connecting the flanges on each side of the bulkhead instead 

 of one openly spaced line, the double stiffeners would probably have shown much 

 less deflection and perhaps have behaved as did the single stiffeners. I do not, 

 therefore, propose to base any rule or general conclusion on the experience with 

 double stiffeners other than that such stiffeners should not be employed except 

 where unavoidable, and that they should then have a better connection along the 

 neutral axis. 



The President: — Is there any further discussion? If not, I will express 

 in your behalf our thanks to Professor Hovgaard for a very interesting paper and 

 we will pass to the reading of the next paper, entitled, "Coaling Warships from 

 Colliers," by Mr. Spencer Miller, Member. 



