5. The levelling culverts may with advantage be arranged so that their inlets are behind the hollow quoin and on a level with the gate platform. of Pressure Sill Suspension Jamb Anti friction Vertical Section. usually near the inlet, the Direction Staunching Rod Jamb Sluice Anti friction Plan. Figs. 180 and 181.-Stoney Sluice. current is immediately formed. Ordinary cloughs are provided with stone (generally granite) jambs, head, and sills, the sliding surfaces being polished. The paddle is slightly larger than the opening-about 6 to 12 inches each way and may be either tapering in thickness or with parallel faces. It is a judicious arrangement to have duplicate paddles, one being actuated by hand in case of mishap to the other worked by machinery. (B) Stoney sluices, so-called from the name of their inventor, have the friction of the bearing surfaces during movement very much reduced by the employment of rollers. The doors are of steel, and a watertight joint is formed by the engagement of a rod in a V-shaped groove. Figs. 180 and 181 explain the arrangements adopted. (2) Fan doors (portes en éventail) are adopted in some instances abroad. They are in the shape of a right-angled triangle in plan (fig. 182), with a vertical axis at the corner, formed by the intersection of two plane surfaces of unequal area. When in position the smaller wing, bearing against a wood-lined frame, cuts off the culvert connection. To open the gate the larger wing has to revolve within a cylindrical chamber. A small discharge 8' 10" 13' 1". Fig. 182.-Plan of Fan Door at Dunkirk. As soon, pipe fitted with a valve serves to set the gate in motion. While the valve remains closed the up-stream pressure keeps the gate shut. however, as the valve is opened the water in the cylindrical chamber escapes, down-stream pressure is introduced into the chamber, and the difference causes the gate to revolve on its pivot, in virtue of the unequal areas exposed. (8) Other doors or gates are in one plane surface throughout, turning upon a vertical axis slightly out of centre. By opening a small valve in the wider panel the pressure on that panel is reduced below the pressure on the other panel, and the gate revolves so as to set itself in a line with the stream. Closing the valve and giving the gate a slight sideways displacement causes the current to act with greater effect on the larger surface, so that the gate automatically swings to. It is locked in position by a turn of the wooden side post. Duration of Levelling Operations. It is often desirable to know how long it will take to level up a lock from a lower to a higher level through the medium of a culvert. If the source from which the water for the purpose = is drawn be maintained at a constant level, or so nearly constant as to be conceivably treated as such, the calculation is a simple one. The theoretical velocity is v 8h, as previously explained. This multiplied by the sectional area of the culvert, or of the culverts if there be more than one, combined with a suitable coefficient of discharge, gives the quantity of water passing in unit time, whence the total time is obtained by dividing into the quantity of water required to fill the lock. Therefore, algebraically, the time in seconds, where Q is the quantity required in cubic feet, a the culvert area in square feet, and c the coefficient of discharge-varying from 5 to 6, according as the culvert is long or short. If the source of supply be not maintained at a sensibly constant level during the process of filling, as when two docks, whose areas are not very excessively unequal, have to be brought to a common level by intercommunication, a suitable formula may be deduced from the same principles, In addition to the previous notation, let A, and A, represent the areas of the docks in question, h1 the height by which the lower dock (A1) is raised, and h2 that by which the higher dock (A) is lowered. Then h1 + h2 h. = The initial velocity of influx is 8h, the final velocity is zero; the mean velocity, therefore, is 4/h. The rate of influx thus becomes 4 ac/h. The quantity of water required to be transferred is, indifferently, A1 h1 or A, h-that is, Substituting this value for h in A, h1, the quantity of water required to be transferred (Q), and completing the equation as in the previous example (42), we finally obtain— Throughout the remarks which have been made in connection with structural operations it has been found convenient to use the word Lock as a more or less generic term to include Entrance and Passage as well. Unless the sense absolutely precludes such an interpretation the reader will consider the principles laid down as applicable and common to all forms of narrow dock waterways. In one respect alone does a passage materially differ in design from a lock. A lock provided with gates has them all (with the possible exception of storm gates) pointing in the same direction, whereas, in a passage, the gates point in opposite directions in order to exclude water from either of the docks which it serves to connect. Having commented as fully as is practicable within the limits imposed by restrictions of space, upon the various matters appertaining to the design and construction of locks, we now pass on to a brief review of some prominent examples selected from harbours in various parts of the world. Canada Lock, Liverpool. Constructed in 1857, with a single chamber, having an effective length of 498 feet, a width of 100 feet, a depth of 35 feet 9 inches below coping, and a draught of 26 feet 9 inches on sill at H.W.O.S.T., this lock was deepened in 1895 to a draught of 33 feet on sill, lengthened to 602 feet, and divided by a pair of intermediate gates into two chambers of 200 and 402 feet respectively. In addition to the three pairs of gates, the lock pierheads are fitted for the reception of ship caissons in the event of repairs being necessary to the outer sills. The old lock was constructed entirely in masonry and intended to serve the additional purpose of a graving dock. Hence the peculiar form of section adopted and shown in fig. 183. The recessed panels in the side walls were for the abutments of shores to the sides of vessels. In the course of alteration these panels were filled up, as also were the lower sluicing culverts, except for short lengths on each side of the gates, where they are now utilised as levelling culverts. The improvement work of 1895 consisted in removing the old masonry floor and replacing it by one of concrete, at a depth of 3 feet 3 inches lower than the new sill level, founded on the boulder clay which underlies the whole site. The concrete was composed of 8 parts of gravel to 1 of Portland cement, with a large proportion of sandstone and granite burrs thrown in. The thickness of the new floor averages 7 feet, and the upper surface is coated with a 6-inch layer of granolithic concrete. A transverse section (fig. 184) shows the floor to be flat for a width of 80 feet and connected with the sides by circular curves of 10 feet radius. The side walls were underpinned with concrete in bays of from 12 to 15 feet in length. A gas- and water-pipe culvert, 5 feet in diameter, is arranged below the floor level. The stone work comprises copings, hollow quoins, culvert quoins, caisson quoins, gate sills, caisson sills, culvert sills and heads-all of Scotch granite, with square quoins of sandstone. The work was carried out in the following manner:- -The outer sill in the tidal basin was reconstructed during low water of spring tides in small sections, within a piled dam, which was pumped out on each occasion. On the completion of the work a stank of concrete blocks was built across it Fig. 184.-Section of Canada Lock, Liverpool, as deepened. between the side walls of the lock, and carried up above the level of high water. These blocks were of uniform size, 11 feet 3 inches by 3 feet by 3 feet, each containing about 100 cubic feet. They were made in wooden moulds at least a fortnight before using, and were deposited by means of overhead steam travellers, double tracks for which, 64 feet wide, ran the whole length of the lock. To ensure watertightness, the blocks were bedded in cement mortar. At the same time, to facilitate their later removal, a sheet of common brown paper was interposed between the block and the mortar. The plan answered admirably, the blocks being perfectly bedded without the undesired adhesion. It is needless to add that the stability of the dam in no way depended upon the tenacity of the joints. The inner end of the lock was enclosed by a cofferdam, constructed of piles and timber framing and filled with clay puddle. A section of the dam is illustrated in fig. 66 (p. 107). When the dams were completed no difficulty was experienced in bringing the work to a rapid and successful conclusion. Three chain pumps with wooden blades, 2 feet 6 inches by |