Boston Wharves.— The ordinary wooden wharves of Boston are constructed as follows: Standard piles, generally of oak, arc driven nine feet transversely and 10 feet longitudinally. They are bound together transversely on top with two girder caps of 6 X 10-inch hard pine and fastened to piles with one-inch screw bolts; the girder caps are let into the piles so that the same arc spaced three inches apart. The outside stringers are of 10 X 12-inch and all inside stringers of 6 X 12-inch hard pine, spaced two feet from centre to centre. The wharves are covered with three-inch hard pine planks. The wharves are braced by brace piles called there spurshores; they are of oak and are shouldered against the outer standard pile at about one foot below mean high water and fastened thereto with one and one-fourth-inch screw bolts. In addition to bracing with piles, each bent has a set of crossbraces of 4 X 8-inch oak, running from a point about two feet above mean low water to the underside of the girder caps. These braces are fastened to each standard pile at each intersection with one-inch screw bolts; a horizontal tie of 4 X 8-inch oak is also placed one foot above mean low water and fastened to each pile with one-inch screw belts. Fender piles of oak are driven in trans verse lines with standard piles close up against the outer ones, and fastened thereto just below the girder cap with one and one-quarter-inch screw bolts. The fender piles are cut off nine inches below the top of the planking and are capped with 12 X 12-inch hard pine caps run ning longitudinally. These caps answer as longitudinal fenders and projecting three inches above the planking also as a curb or backing block. Mooring piles of oak are driven just in side of outer stringers and are held in place by four-inch planks fitted down into adjoining stringers and around mooring piles. The cor ners of these wharves are similarly piled and finished as are the wharves of Philadelphia and New York. A safe load for these wharves would be about 300 pounds to the square foot.
bents are five feet apart from centres trans versely and before being cut off at the proper level, they are straightened and stay lathed into position. They are then hound together trans versely with girder plank of 6 X 12-inch, gained into piles, equally on each side, leaving a tenon of four inches thick, 12 inches long and the width being the full diameter of the pile. They are fastened to each pile with two screw bolts. The cap proper is a single piece 8 X 16 inches laid on flat, covering the pile and flush on each edge with the girders; they are drift-bolted to the piles and well spiked to the girder planks or clamps, as they are called. The wharf is braced in the following manner: At the line of mean low water two girders of S X 10 inches are fastened to each pile in each bent, one on either side of the pile; the spaces between these planks and the four outer piles on each side are chocked with 12X 12-inch timbers to the girder plank. The bents are =nab' braced with 'A' braces of 5 X 10 on side, four in number, dividing the bent into two panels, that is, a set of braces extend from the girder either way from the centre of the wharf to a point at the under side of the deck line, distant from the outside of wharf one-fourth of its entire width. From the outside of wharf. at this same lower girder, another set extends to the bottom deck, and, meeting the first set, they are bolted to each pile at each inter section with galvanized screw bolts. The
stringer system is composed of an outside stringer of 12 X 14 inches and intermediates of 6 X 14 inches laid two feet six inches from centres. They are gained out at caps one inch. The floor is composed of two layers of three inch plank, dressed to a uniform thickness; the first is laid at right angles to the axis of the wharf, and the planks are placed six inches apart, these spaces over the stnngers being filled solid for the full width. The planks in the outer section of this layer, about 12 feet in length, are creosoted with 14 pounds icf dead oil to the cubic foot; they are fastent01_,to the Philadelphia Wharves.— These wharves. with the exception of two outer bents, arc con structed a, follows: Standard piles arc, as pre ceribed by the rules of the board of port ward ens, driven in bents located longitudinally, 10 feet from centre to centre. The piles in these stringer, with wrought spikes one-half inch square and seven inches long. The sheathing plank or upper layer are laid close and at an angle of 45 degrees with the axis of the wharf. and are spiked to the lower plank with five-inch wire nails averaging three feet apart. The baciong log or curb is a 10 X 12-inch oak tim ber, raised above the planking of the wharf and supported on blocking of 2 X 12 inches. laid five feet apart. Fender and brace piles are used only on the outer bents. The usual system of fenders is a series of 6 X 8-inch white oak tim bers placed horizontally around the wharf be tween the top and the line of mean low water. They are placed about six inches apart and are tastened to vertical furring pieces of 8 X 12-inch yellow pine which are bolted to the front row of standard piles in each bent, these piles being surfaced off to receive them. The two outer bents arc constructed as to spacing, protection, number of piles and braces as are the New lurk wharves. They have rounded corners, *hoe oak fender piles, and in addition, fender piles at the ends of these two outer bents; they have also brace piles and corner bands and chocks connecting fender piles.
Comparisons.— Comparing the construction of eastern wharves with those of San Francisco, leaving aside those parts in the eastern wharves which are designed to resist the floating ice, the details of the construction of the San Francisco wharves are simpler; having no gains or tenons, they are not so apt to suffer from dry rot; anti the fact of having but few joints in caps and stringers, they are, consequently, in this respect superior to the eastern structures. However. the construction of the San Francisco wharves is better, owing to the better materials for which the coast is famous. The length of tim bers for wharf construction in the cast very rarely exceeds 40 feet, but generally timbers up to 30 feet in length only are specified and used. In San Francisco wharves, timbers of from 60 to IOD feet and over in length are frequently employed and arc to be had with only a very small additional cost. With piles it is the same, in eastern wharf construction; a pile 60 feet long is considered a very long pile, whereas on the Pacific Coast, piles from 100 to 130 feet in length can be had at any time. The life of the superstructure of the above-described wharves, especially if covered with sheds and buildings, is from 15 to 25 years, aside from the actual wear of the planking, but in sea water the life of an unprotected pile is from six months to three years owing to the ravages of the marine pests.