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July, 1910 ing filled with earth, The enormous cost and the difficulty of finding suf- ficiently solid foundations for such structures is a strong argument against them. While such piers are perman- ent, it is claimed that the new San TAE MARINE. REVIEW ing, while being good as an average is somewhat irregularly performed, the teredo has managed to reduce the the- oretical 25 years of life to actual pe- riod of about 12 years. For these reasons concrete piles of 200 a pile. It was decided that this soil was capable of safely supporting a load of 10,000 lb. per sq. ft. Actual test loads up to 30,000 lb. showed no settlement. The pier foundations were proportioned accordingly. The piles Piztr UNDER CONSTRUCTION, SHOWING CONCRETE PILE Francisco piers supported on concrete piles are equally permanent, much less expensive and easier to construct. On account of the activity of the two species of pile worms, the lim- noria terebrans above low water and the teredo navalis below low water, the life of untreated piles is confined to a few months. Under favorable circumstances a creosoted pile has a life of from 20 to 25 years. Enperience goes to show, however, that due to two styles have been adopted at San Francisco. The older style, invented by Howard C. Holmes, consisted of a core usually of the three piles driven in a close cluster surrounded by a re- inforced concrete cylinder. The new design, adopted for the piers under consideration, is a modification of Mr. Holmes, patent devised by Ralph Bar- ker, assistant state engineer, © The modification is suitable only for the conditions existing at the point where IN PLACE. consist simply of a concrete cylinder reinforced with eight l-in. square twisted bars and also a spiral wrap of 34 x %-in. flat steel, laid with a pitch of 9 in. The outside diameter of the concrete shaft is 3 ft. 6 in. The pile terminates at the bottom in a cast iron bell which gives a bearing at the foot of from 21% to. 26 54. ft., varying diameters of bells being used. In setting the piles,a.wooden form built of fir staves hooped with steel bands Pier 38, Juzy 28, 1909, SHOWING ForMs AND FALSEWORK IN PLACE. the many vicissitudes to which a pile is subjected, especially where exposed to collision from vessels, where care- less employes find it necessary to bore holes and neglect to properly protect them and where the work of creosot- these piers are constructed. Exhaust- ive soundings were made at the site, and: at a depth of 50 ft. below the floor of the piers there occurred a stratum of stiff clay and sand which it was very difficult to penetrate with spaced 2 ft. on centers is sunk to the hard pan level, the cast iron bell or shoe being bolted to the bottom of this form. All the mud and water is pumped out of the form and the rein- forcing and concrete is inserted. The