was encountered (with occasional boulders imbedded), with the exception of an out-cropping of rock, which occurred about half way up the Dock, continuing to the end, and under the caisson chamber and engine house foundations.

The whole of the foundations of the entrance works are of cellular brickwork, laid in 3 to 1 Portland cement compo, and the pockets filled in with concrete.

The walls and Dock entrance are 7 to 1 rubble concrete, faced with sandstone in 2 feet courses. The sandstone facing of the Dock, according to the contract drawing, was in 1 foot courses; but as good stone was easily obtainable of large size in the district, it was ultimately decided to adopt 2 feet courses. The sandstone was obtained from Salt Spring or Admiralty Island, and the granite from Nelson Island, respectively distant from Esquimalt, 50 and 100 miles. A skin of 9 inches in thickness of 5 to 1 Portland cement fine concrete was introduced into the bottom of the whole of the foundations, against the backs of all the walls, and also behind the brickwork and stone facing work, and generally throughout the works.

The Dock side-walls are built vertical, the upper portions being carried by rubble concrete arches. Under the bottom of the Dock there are 6 arterial box drains, laid in 5 to 1 Portland cement porous concrete, which are connected with the rubble drains running behind the walls in each arched recess, the whole of which discharge into the drainage pump well.

The inverts are 112 feet radius, the outer being 15 feet wide, and the inner 20 feet, both of which are faced with sandstone with a hearting of brickwork and 7 to 1 concrete, (Figs. 10, 11). The caisson berth meeting faces and quoins of the invert are of granite, which are fine-axe dressed for 12 inches in width, and have a projection of of an inch. (Fig. 10).

The invert at the bottom of the caisson chamber is of brickwork set in 3 to 1 Portland cement compo, and founded on 7 to 1 concrete, and the walls of the chamber are of hammer-dressed sandstone, in 2 feet courses, with 5 arched recesses on each side. The chamber is provided with stop quoins (Figs. 13 to 17) at its entrance, and by means of balks of timber inserted therein, can be converted into a dock for painting or repairing the caisson.

The cast-iron boxes carrying the rollers on which the caisson travels are set in brickwork on the bottom of the chamber and berth. At each end of the caisson chamber pathway there is a scouring culvert, which can be used, when desired, to clear the roller pathway of any mud that may accumulate, (Fig. 10).

The dock is provided with four timber slides and stairs, of finely dressed masonry, two at the head and two at the stern. There are also twelve cedar double fenders, with ladders in them of 4 feet in width, six patent hand power capstans, and the necessary mooring posts, a powder magazine, all necessary lavatories, &c., three hydrants on each side of the dock, with a first-rate water supply. Outside the entrance to the dock are two wrought-iron buoys attached to screw moorings by a 2 inch stud cable, for the purpose of facilitating the docking and undocking of vessels. The works are now lit up at night by electricity. The engine and boiler house and chimney shaft are faced with hammer-dressed ashlar, backed with brickwork in Portland cement. The chimney shaft is 90 feet 9 inches above coping level; and it was found necessary to go to 45 feet below coping for foundation for the same. The paving at the centre portion of the dock bottom, for a width of 10 feet, consists of two courses of stone 2 feet in depth and 1 foot 9 inches in width, and filled in between with five courses of 18 inches in depth, and the remaining portion of the dock bottom is paved with twenty courses of stone 2 feet in depth by 18 inches in width, the whole being laid in Portland cement compo.

The discharge pipe from the auxiliary drainage pump is carried through the quays, and across the caisson chamber immediately under the surface of the quays, and down the face of the harbour quay wall.

There are also two culvert mouths, 4 feet in diameter, in the faces of the harbour or quay walls. The one on the west side is the discharge from the main pumps, and the other for scouring the caisson berth at its eastern end.

One of Mr. Kinipple's patented Travelling and Folding Bridge Caissons was constructed and erected for this dock, by the Dominion Bridge Works Co., at Lachine, Quebec, and transported in pieces by the Canadian Pacific Railway to Esquimalt. The caisson illustrated is provided with keels, which travel on two lines of rollers placed on the bottom of the chamber and caisson recess, (Fig. 19).

The Folding Bridge on the top of the caisson is supported by levers having adjustable tail weights, which together form a parallel motion. The raising and lowering of the platform is effected by rollers on the nose of the platform against curved plates placed in the abutment.

The caisson, which is hauled by steam power, may be drawn in or out of its recess in less than five minutes, and in any weather. It is divided into two parts, the lower being an air-tight chamber of sufficient capacity to reduce the weight of the caisson on the rollers to a minimum,

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and the upper a flotation chamber, from which the water is pumped out by means of a Pulsometer whenever it is necessary to float the caisson out of its berth. Abrasion of the meeting faces of the caisson and granite sills and stop quoins is prevented by the keels having "swells" in them, as illustrated (Fig. 23), which ensures a clearance between all the meeting faces, when the caisson is being hauled into or out of its

recess.

The sides of the caisson are vertical, but are bevelled horizontally, the inner face being of less width than the outer, in order that by moving the caisson a short distance back into its chamber, and allowing the caisson to float high enough to clear the invert or sill, it may be turned round and floated out, when necessary, for repairs, &c. The caisson, when afloat, can also be berthed against the outside meeting face of the outer invert, and by this means the available length for dockage would be increased by 31 feet, and the length of the dock from the inner face of the caisson to the base of the circular head would then be 481 feet.

By constructing the caisson as above described, the usual battered sides are dispensed with, and a saving of about 10 feet in width of the entrance is thereby effected.

The caisson is constructed of a series of horizontal and vertical angle and irons, with cross diagonal bracing 4 feet 6 inches apart. The outside plating varies from inch to inch in thickness. A teak meeting face or rubbing piece 1 foot 3 inches wide is attached to the inside and outside faces of the caisson, following the vertical sides and radius of the invert.

The displacement of this caisson is 530 tons, and its entire weight equals 294 tons, made up as follows:-Cast iron, 63 tons; brass, 4 tons; wrought iron, 199 tons; teak face and other iron work, 28 tons; the weight of the concrete ballast, over 180 tons.

The width of the rising and falling platform is 10 feet, the height of the caisson from the inner side of the keels to the coping level is 34 feet 10 inches, the length 67 feet 2 inches on the inner or dock side, and 71 feet 2 inches on the outer or harbor side. The keel blocks are of cast iron, in three pieces, wedge shaped, the lower piece is checked into the stone paving, and each block is provided with a hard wood cap and a rubbing piece on top.

It may be of some interest to mention that the above rates are less than those at Yokohama, Japan, or than those at San Francisco, U.S.A., (which are from 100 to 300 per cent. higher), should a vessel occupy the dock from 7 to 10 days.

The Royal Naval Dockyard adjoins the Graving Dock property, and to the westward thereof, thereby affording great facilities for repairs to any of Her Majesty's ships.

The total cost of the Graving Dock Works, inclusive of the site, the cofferdam works, as well as the engine and boiler houses, pumping machinery, and caisson, amounted to about £180,000.

Mr. William Bennett, M. Inst. C.E., M.Can.Soc.C.E., was the Resident Engineer from 1875, until the completion of the works in 1887, and Mr. Francis O'Reilly was for two years his assistant.

From the Drawings accompanying this paper, Plates X and XI have been prepared.

[Mr. Perley.

DISCUSSION.

The construction of the graving dock at Esquimalt was undertaken by the Government of British Columbia, in accordance with plans prepared by Messrs. Kinipple & Morris, of London, England.

In 1876, the coffer-dam was commenced; but owing to failure on the part of the contractor, the provincial authorities took possession, and completed it in 1879.

During 1876, the pumping machinery arrived in Esquimalt, and remained in store until 1886, when it was eventually put in place.

In 1879-80, a contract was entered into with Messrs. F. B. McNamee of Montreal for the construction of the dock proper, it being stipulated that the cement (Portland) should be supplied by the Government. After arrival in British Columbia, Messrs. McNamee & Co. associated themselves with some local contractors, but this did not tend to facilitate the progress of the work, which was slow and delayed for the want of cement, the result being that in April, 1882, operations ceased entirely. Possession of the works was taken by the provincial authorities, who carried them on by day labour until August, 1883, when they again stopped, and passed into the hands of the Dominion Government, and under the direct control of the Minister of Public Works.

Steps were at once taken to complete the dock. The works were placed under the direct charge and control of the writer as chief engineer, the services of Messrs. Kinipple & Morris were dispensed with, and they had not anything to do with the actual construction and completion of the dock; Mr. Wm. Bennett being retained as resident engineer.

No change was made in the plans, but the original specification was revised, and the first set of tenders having been rejected, a second set was obtained, and the work was let in 1884 to Messrs. Larkin, Connolly & Co., who were at that time proceeding with the construction of the graving dock at Levis, Quebec. Under their management the dock was brought to completion in 1887.

As designed by Messrs. Kinipple & Morris, the dock was only 380 feet in length on the floor, the plans providing for an extension at a future date, the works in connection with which occupied a length of 50 feet. These works were abandoned by the writer as useless, and a