All the sound piles were redriven elsewhere. There is no reason for believing that the Summary of Docks C, D and E would have been greatly affected had it been possible to include piles from Docks A and B. Hence it is likely that 75 per cent. of the original creosoted piles are still in service. Attention is also called to the fact that many of those slightly attacked were redriven inshore, with the result that about 80 per cent. of the original total are still serving. Investigations of the Dumbarton Cut-Off trestle of the Southern Pacific Company, at the extreme south end of the Bay, have disclosed the presence of Xylotrya, Teredo navalis, Limnoria and Sphaeroma. Teredo diegensis has been found at only one point in the Bay, at the Schaw-Batcher ship yards, near South San Francisco, on the West side. The foregoing briefly outlines the manner in which San Francisco Bay has become infested with five forms of marine borers, with conditions such that they can thrive and work severe damage. The brackish water at the north in Carquinez Straits and Saisun Bay is infested with Teredo navalis and Sphaeroma, and the water of San Francisco Bay proper, with high salinity, is infested by both of the above, together with Xylotrya, Limnoria and Teredo diegensis. SAN PEDRO AND SAN DIEGO BAYS.-Both of these harbors have suffered attacks of Xylotrya and Limnoria, with Teredo diegensis present in a minor degree. Test piles were driven at both places, including untreated piles, old creosoted piles from Long Wharf, and freshly creosoted piles. Those untreated have already been severely attacked by Limnoria, and one of the Long Wharf piles at San Pedro shows slight evidence of borer action. TESTS. The following list shows special service tests now being observed by the Sub-Committee: 1. Four sets of 7 piles each driven as follows: March, 1920, Northern Pacific Ry. Co..... Seattle Tiburon San Pedro San Diego Each set includes 1 untreated fir pile, 2 freshly creosoted fir piles, and 4 creosoted fir piles taken from Old Long Wharf in 1919. 2. Twelve creosoted Douglas fir piles from Old Long Wharf, driven as brace piles in Southern Pacific Company Wharf No. 2-Oakland Pier, October, 1919. 3. Sixteen eucalyptus piles driven in dolphins of Alameda Ferry Slip of Southern Pacific Company, 1921. 4. Sixteen eucalyptus piles driven in dolphins of Oakland Auto Ferry Slip of Southern Pacific Company, 1921. 5. Eighteen dolphin piles in Georgia Street Wharf, South Vallejo, of Southern Pacific Company covered to above high water with "Moran" paint, 1921. 6. Eighteen dolphin piles in Georgia Street Wharf, South Vallejo, of Southern Pacific Company, covered to above high water with "Paraffine" paint, 1921. Insufficient time has elapsed since the inauguration of the tests above enumerated to allow a conclusive report of definite results. All of the creosoted piles of Tests Nos. 1 and 2 reported on to date are in good condition. One of the old Long Wharf creosoted piles at San Pedro shows a slight Limnoria action. The untreated pile of the set at this location has been eaten by Limnoria to a depth of 2 inches, near lowtide level. The San Francisco Bay Marine Piling Committee has established a laboratory and aquarium on the Oakland Pier Wharf of the Southern Pacific Company, where living marine borers can be observed working in specimens of wood submerged in glass tanks. This gives an excellent opportunity to see the syphon which the Teredo, or Xylotrya, extend out of the entrance to their burrows into the water, and through which they obtain their nourishment. This is about the only manner in which this delicate syphon can be seen because of the fact that the borer draws it back into the wood at the slightest disturbance, or when taken out of salt water. The ejection of wood "sawdust" can also be watched, and likewise the breeding process. In addition to these tests, your Sub-Committee has under observation numerous structures of creosoted piling just completed by the Southern Pacific Company, viz.: Auto Ferry Slip, Oakland; new Ferry Slip, Port Costa; Ferry Slip, Benicia; etc. In conclusion, the Sub-Committee makes the following recommendations: 1. That the co-operation of Pacific Coast bodies in position to contribute data on the condition of marine borers in the various harbors be further solicited. 2. That standard Service Records be prepared and that owners of marine wharves be requested to institute them, and place the results at the disposal of this Sub-Committee. 3. That publicity be given to the nature of the individual marine borers under investigation, so that correct identification may be possible. 4. That temperature and salinity tests be made at regular intervals in the main harbors. 5. That efforts be made to co-operate in the movement now under way to cause the removal of unused marine structures, which are the breeding places of marine borers. 6. That biological study of the marine borers be continued and given as wide publicity as possible. 7. That the analysis of all structural timber used for marine substructures be investigated to ascertain qualities of absorption and adsorption. 8. That continuous tests be made by submerging timber treated with creosote oil in several degrees, ranging from the portion in which all the toxic ingredients have been removed to that of the full oil. 9. That continuous tests on the various commercial forms of surface coverings be made. 10. That service records and general data, including the element of cost, on the various forms of piling material other than timber be investigated. 11. That construction methods be further developed and the theories be disseminated among construction forces to cause a more careful handling of treated material about to be put in place. Appendix E RESEARCH WORK ON MARINE PILING HERMANN VON SCHRENK, Chairman; Z. M. BRIGGS, S. D. COOPER, A. B. ILSLEY, W. H. KIRKBRIDE, Sub-Committee. Wooden piles used in marine construction have since the earliest days been subject to attack by various forms of marine borers, including members of the genera, Teredo, Xylotrya, Limnoria, Sphaeroma, etc. Very little definite information, however, is available with reference to exact distribution of the various forms, their specific identity, the conditions under which they live, influence of temperature and salinity of waters, the methods of reproduction, feeding habits and kindred points. The comparatively recent attack on marine structures in San Francisco Bay and in north European waters has brought the subject of marine borers and methods to be used to protect against their ravages prominently to the attention of engineers in all parts of the world. As this is a matter of very vital interest to the members of the A.R.E.A., your Committee has prepared a brief discussion of this subject. RECENT DEVELOPMENTS.-While marine borers have been more or less prevalent in the warmer waters tributary to the United States and Canada, no unusual activities were reported until 1917, at which time unusually severe attacks of marine borers were reported by Dr. A. L. Barrows at various points in San Francisco Bay. The outbreak in San Francisco Bay has continued with remarkable vigor so that to date approximately $20,000,000 worth of damage, more or less, has been reported from that region alone. While these reports were coming from San Francisco similar reports were being received from various north European waters, particularly along the coast of Norway and Sweden, and from various points in England. The European interest in this subject is very well shown in the recent appearance of a long report by a special committee of the British Institution of Civil Engineers appointed to investigate the "deterioration of structures of timber, metal and concrete exposed to the action of seawater." The report of this committee, consisting of a volume of 301 pages, with thirty-three plates and thirty-seven figures, deals in part with marine borer attack on wooden structures in all parts of the world and is a valuable contribution to this extremely important problem. Another recent report comes from Denmark, the result of investigations of a joint committee of the Danish, Swedish and Norwegian Engineering Societies. RECENT INVESTIGATIONS.-Stimulated by the recent attacks just referred to, investigations with reference to marine borers have been started in various parts of the world. The first contribution of impor tance dealt with the San Francisco Bay situation and appeared as a report of the San Francisco Bay Marine Piling Committee of the American Wood-Preservers' Association, in 1921. This valuable report gives a complete description of the attack, discussion of the various forms of borers found, a description of the physical conditions of San Francisco Bay with particular reference to salinities and temperatures, and suggestions for protective methods to be used. Various activities in Europe are also to be noted, particularly the report of the British Institution of Civil Engineers already referred to, and work done in Sweden and Denmark. Shortly after the San Francisco Bay appearance it was recognized that environmental conditions probably had a good deal to do with the virulence of attack at that point. The salinity of San Francisco Bay had risen considerably due to reduction on fresh water run-off from the western slopes of the Sierra. Recognizing the probable vital relationship between attacks of marine borers and salinity and temperature of waters in which these organisms thrive, careful determinations as to salinity and temperature have been made in San Francisco Bay and investigations are now in progress to more clearly define the extremes of salinities and temperature under which the various species develop. Recognizing the possibility of unusual marine borer attacks in other parts of the country, your Committee has endeavored to obtain information as to salinity and temperature at various points on the Atlantic, Gulf and Pacific Coasts. In the report by Sumner et al., “A Report Upon the Physical Conditions in San Francisco Bay, etc.," University of California Publications in Zoology, July, 1914, a comparison is made between the annual water temperatures for San Francisco Bay, Woods Hole, Mass., and points in Chesapeake Bay, which are of interest in this connection: "The mean latitude of these points in Chesapeake Bay is very nearly the same as that of San Francisco Bay. The mean annual water temperature for the former bay, computed from the records referred to, is 14.38° C. (57.89° F.), that for the latter bay being 12.91° C. (55.23° F.). The chief difference between the temperature conditions of these two bodies of water lies, however, in their respective annual ranges. In Chesapeake Bay this amounts to 22.12° C. (39.82° F.), while in San Francisco Bay it is not much more than a third (38 per cent.) as great, being 8.35° C. (15.03° F.). Thus the equable climate for which California Coast is famous is reflected in (we should say, is largely due to) the equable temperature of its coastal waters, though the direction of the prevailing winds is likewise an important factor." "The resemblance between the Chesapeake Bay curve and that for Woods Hole, Mass., is sufficiently striking. The latter is based upon the monthly means for a period of six years, as recorded at the Woods |