130 COLLAPSE OF TEXAS TOWER NO. 4 



Commander Foster. Well, the substitution of tlie braces, as I said 

 in my statement, sir. 



Mr. KJENDALL. Well, with reference to the pin tolerances, I believe 

 the original design was one sixty-fourth of an inch, is that correct? 



Commander Foster. That is basically correct. 



Mr. Kendall. Now, what were the changes subsequently made and 

 approved by you ? 



Commander Foster. An increase to a maximum of one-sixteenth 

 in all cases except what amounted to the top panel bracing, in which 

 case, one-eighth. 



Mr. Kendall. Will you point out on the model the top panel that 

 you refer to ? 



Commander Foster. That would be this whole plane of bracing 

 at the —25-foot level; these connections [indicating]. 



Mr. Kendall. In other words, you permitted an increase to 

 one-sixteenth inch in all pin connections on the tower except the 

 top level of bracing, in which you permitted an increase to one-eighth 

 inch ; is that right ? 



Commander Foster. That is right, sir. 



]Mr. Kendall. "\Yliat was the reason for increasing those tolerances? 



Commander Foster. As I mentioned in my statement, sir, the con- 

 tractor had experienced considerable difficulty in trying to make up 

 these connections, and as I am sure you can realize, when you are 

 tryinji to insert an 8-inch pin, which may weigh 300 to 400 pounds 

 125 feet in the air through five layers of plates, with one sixty-fourth 

 inch difference in diameter between the hole and the, pin, this is a 

 difficult situation. However, before approving this, we had con- 

 siderable thought and consultation with the architect-engineer and 

 with full loiowledge that this might have some effect on the stnicture, 

 for which reason I took it up with the architect-engineer; I did refer 

 to him, and after his approval and based on my own assessment of it, 

 I granted that approval. 



Mr. Kendall. Did you have any reluctance, hesitancy or doubt 

 about the wisdom of granting that increase in tolerance ? 



Commander Foster. I did not, sir. 



Mr. Kendall. As an engineer, do you not believe that the increase 

 in the tolerance to one-eighth inch permitted some motion in the tower 

 as erected ? 



Commander Foster. Well, it certainly would permit more motion 

 than a smaller tolerance would ; yes, sir. 



Mr. Kendall. So that it actually permitted more motion than was 

 called for by the original design, is that correct ? 



Commander Foster. I would say that would be a true conclusion ; 

 yes, sir. 



Mr. Kendall. Would it be reasonable to assume that with the pas- 

 sage of time the motion of the sea and the sway of the tower, the 

 impact of the pins as they fetched up would increase the wear and the 

 tolerance ? 



Commander Foster. I am not sure, sir, that impact is the essential 

 element here. 



Mr. Kendall. Well, I may be using incorrect terminology engi- 

 neering-wise, Commander; I am sure you understand the essence of my 

 question, so will you please answer on that basis ? 



