vith arsenlous trioxide, copper sulphate, and zinc sulphate, vas 

 reported to have remained sound. 



h. Electrolytic, open- tank treatment of piles hy the use 

 of copper sulphate, sulphuric acid, and other chemicals proved of no 

 value against Teredo attack at Sitka, Alaska. Figure 7 and 8 show 

 samples of piling treated hy the above method which were completely 

 destroyed in less than two years. 



c. At the Puget Sound Wavy Yard, Bremerton, Washington, 

 it was found in ipUi)- that test "boards made of Douglas fir, western 

 hemlock, western white pine, and cedar were similarly filled or 

 riddled hy Bankia setacea. Whether the Douglas fir panels were of 

 heartwood or aapwood, they were riddled hy Bankia setacea , and were 

 attacked hy Limnoria the same as were the other kinds of wood. 



5. Protection of Wooden Hulls . In 19^J<- a method was developed 

 at the U. S. Coast Guard Training Station, Mayport, Florida, to protect 

 the hulls of wooden "boats; marine horers were reported to have "been 

 eating away the keels of small boats in 12 to I8 months. The new method 

 was to install a 1-inch worm shoe on the keel, with a layer of tar 

 paper (commercial felt) between it and the keel. This was reported to 

 repel marine borers for $0 to 120 days, as the borers were reluctant 

 to penetrate felt, and instead, bored horizontally along the worm shoe. 



AI.06 Use of the narrative and Tabular Summaries 



The following paragraphs, 1 and 2, explain the use and application 

 of the 56 narrative summaries which constitute PART A of this report, 

 and of the tabular summaries at I60 world-wide locations which conrprise 

 PART B, It should be noted that the chief limitation in the use of the 

 tabular summaries arises from the fluctuations which may occur from time 

 to time in the degree of attack by various borers at a given locality, 

 depending upon various conditions which favor or retard the development 

 of the organisms. 



1. Narrative Si™™aries . The narrative summary at a given location, 

 as given in PART A of this report, conveys the best picture of the general 

 trend of borer activity for the years reported. Some information given 

 in the narrative summary cannot be shown in the tabular summary. Thus 

 the narrative summary may indicate slight chance of attack by certain 

 borers, while in other cases attack by Teredinidae , Limnoria , or other 

 borers may be consistently more severe, or less severe. Fluctuations 

 in attack, over a period of years, also are indicated, as axe the local 

 variations in attack at different parts of a given harbor, where salinity 

 or other local conditions vary. 



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