21 



were built and many new preservatives for timber were tried with \-ar\ing success. 

 In this period the Robbins process was found to be comparatively ineffective because 

 the amount of creosote injected was insuftiiieiit and soon leached out, lea\inti the 

 timber unjirotected. 



THE THIRD PERIOD: SOUND CREOSOTE AND UNSOUND CONCRETE 



Durinp; the years 1888 to 1890 untreated timber and that treated by the plausil)le 

 but unpro\ed preservatives or processes of e\er\- new inventor began slowly to be 

 mixed to a larger and larger extent with that treated with creosote by the Bethel 

 pressure-cxlinder process, which had consistently proved its value ever since its 

 introduction in England in 18,^8. Since the light treatment of the Robbins process 

 was found effective until it le.ulu-d out , the obvious conclusion was that the amount 

 injected must be increased. Mr. John Hethell, who had invented and patented the 

 creosotlng process by pressure impregnation, had stated that piling should be treated 

 with ten pounds of creosote per cubic foot; but he was simply one of innumerable 

 inventors of the time, his opinion was not generally accepted, and practically fifty 

 years thus elapsed during which the process was under trial, before his opinion was 

 confirmed. During this time gradualh' accumulating experience indicated that failures 

 with creosote treatment are failures of its application to the timber rather than of the 

 creosote itself and that his invention gave greatest promise of success over other 

 processes. In 1888 the Board of State Harbor Commissioners reported as follows: 

 "The Board has given much attention to the various methods for the preservation of 

 piles and timber from the ravages of the teredo and limnoria. The engineer of the 

 Board is emphatic in his opinion that thorough creosoting is the best remedy that 

 has so far been used for this purpose, and reports that this has been demonstrated 

 both in Europe and this country." 



In 1889 the Southern Pacific Company treated about one thousand piles at its 

 temporary creosoting plant at San Pedro, the injection of creosote being about fourteen 

 pounds per cubic foot. These were driven in Oakland Long Wharf in the next year 

 and remainetl in the structure in excellent condition until it was removed in 1919. 

 Many of the piles removed were redriven elsewhere and are still in serviceable con- 

 dition after thirty-four years of exposure to date. A complete report of these piles is 

 given in Proc. Amer. Wood Pres. Assn., 1920. In 1890 the Southern Pacific Company 

 built a permanent creosoting plant at Oakland where it has subsequently treated all 

 its piling for marine structures. 



In that same ^ear the sea wall north of Market Street was completed, practically 

 closing out the area of what had been Verba Buena Cove. Recalling that the first 

 whar\es of this region were started in 1849, it follows that the maximum economic 

 life of such structures was forty-one years. However, the reclamation of the cove 

 had caused the advancing fill to cut off the early portions, so that the actual economic 

 life of those structures forced to cease operation because of the seawall was much less 

 — probably about twenty years. 



In 1895 a boiling method for the rapid artificial seasoning of piles with creosote, 

 followed by pressure impregnation with that preservative, was patented by Mr. John 

 D. Isaacs and Mr. W. D. Curtis. (See Proc. Amer. Wood Pres. Assn., 1917,77.) Some 

 thirteen thousand piles so treated were driven in the next few years in the Southern 

 Pacific Company's Long Wharf. Most of these were likewise found in good condition, 

 as were the one thousand from San Pedro, when the structure was removed in 1919. 



In the same decade, beginning 1888 to 1890, which witnessed the extension of 

 the creosote treatment of wooden piling, appeared the first crop of the superficial pre- 



