The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

February, 1912 two at the bottom and two at the top of the cribs. The cribs are filled with sand and capped on top by a concrete slab which is 3 ft. thick un- der the supporting columns or piers. The outer edge of the concrete slab is built-up in the form of a coping as indicated in Fig. 5, and the face of the wall is protected from contact with the ore boats by two 10-in. 30- lb. I-beams set in the cement, as shown in Fig. 5. No wooden tenders are used. The posts supporting the bins are solid. concrete; 7 tt © 2 it 9 in: in cross section. They are 31 ft. 10 in. in height, exclusive of the pedestals, THE MARINE REVIEW substructure is further stiffened by 16 tower bays, one at each end and one in the middle, the adjacent piers in the towers being connected by a 12-in. concrete wall. The expansion and contraction of the structure is provided for by the insertion of 15 expansion bays equi-distantly spaced. The bin walls or partitions which connect the two piers in each bent are composed of a series of columns built of plates and Z-bars.- There is a column under each track stringer. These columns are connected by three 8-in. plates, as shown in Fig. 5, so that the bin wall becomes a beam extending across the deck from pier . being 55 steel columns suitably tied together by diagonal bracing, these columns surmounted by stringers or girders which carry the load between the bents, the bin floors being carried by a series of A-frames. The walls between the bins are merely parti- tions. In this dock the _ superstruc- ture is supported on a series of con- crete piers, properly tied together by rows of concrete struts, the ore bins, tracks, etc., being carried by the par- titions between the bins, which in this case act as large transverse' beams. The semi-circular ends of the bins are built of steel plate varying in thickness from % in. at the top to Half Yon at : Halt front elevation back of hand-railing K-24" Bg" c Fic. 4--Detait oF OrE CHUTE AND Door or Two Harsors Dock. ~ which are 8 ft. 6 in. in height above the water line. .The only reinforcing in the posts consists of 7%-in. vertical rods embedded 4 in. from the sur- face at the corners. These are mere- ly intended to protect the corners from injury and not to lend stiffness to the column. These concrete sup- porting columns are in reality piers. They are tied together longitudinally by two sets of reinforced concrete beams, each beam being 2 ft. deep and 1% ft. thick. The upper row of beams connects the tops of the piers, as shown in Fig. 5, and the lower row is connected at a point 14 ft. 11 in. above the top of the pedestals. The to pier and supporting all the loads imposed upon the superstructure. To give a smooth .surface to the inside of the pockets, the steel work in the walls is covered by concrete which is flush with the flanges of the Z-bar columns. A _ series of seven Il-beam purlins connects the bin walls and supports the floors of the pockets. The floors consist of a 6-in. creosoted fir-filling layer with a 4-in. hard ma- ple surface laid on the fir. The con- struction is quite different from previ- ous design. Heretofore ore dock iraming has been merely a modifica- tion of standard trestle construction, that is, the structure is supported on % in. at the bottom, riveted together in courses exactly like the shell of a horizontal "tubular 'boiler, . The semi-circular form, of course, is self- supporting and no posts or bracing are necessary to resist the outward pressure of ore. As stated, this de- sign prevents arching of the ore, the pockets emptying themselves prac- tically clean. The ore chute doors are of the ordinary sliding type and are not counter-balanced. They are _ hoisted by means of a hand winch, so geared that a pressure of 35 lb. on the han- dle is sufficient to hoist the door.