237 



1919, at just the proper season to lie attacked liv Bankia, gave service until Xoveniter, 



1920, when they were so weakened that it was found necessary to remo\'e them. Thus 

 they lasted for about 20 months. .\n untreated pile driven in the Northwestern Pacific 

 wharf at Tiburon in 1919 was not entirely destroyed when exaniiiied on December 

 14, 1921, although exposed to the combined attack of Bankia and l.iiimon'a. and some 

 Teredo, during the intcr^■cning two \ears. 



Fig. 88. Cross-sections of a companion timber to that shown in figure 87 ; exposed during the same period. 



(1) Section 10 feet, 2 inches above mud line. 



(2) Section 6 feet, 6 inches above mud line. 



(3) Section 6 inches above mud line. 



Note contrast between inshore (right) and offshore (left) sides in the intensity of attack and de- 

 struction. 



On the other hand, attack by Bankia at its worst can hardly be exceeded by the 

 worst instances of damage by Teredo. L'ntreated Douglas fir piling dri\-en in the false 

 work of the new China Basin Warehouse in San Francisco, in February, 1922, was 

 thoroughlv riddled at the mud line by Bankia when examined on August 18. An in- 



