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Alongside of the swamp are the boiler and engine-houses, the latter containing three engines which are employed in pumping the water from the swamp to a reservoir elevated 140 feet above the sea level, and also to an overflow beyond at an elevation of 216 feet above the sea level.

Each engine is of 70-horse power, condensing, with a cylinder of 58 inches diameter, and 8 feet stroke, and makes 11 strokes per minute, with a pressure of steam 25lbs per square inch, and working a pump of 2 feet diameter and 8 feet stroke.

Two of these engines are connected to one crank shaft and fly-wheel, but may be worked separately, as they usually are, except on Saturdays, when both are worked at a speed of six strokes per minute, in order to fill the reservoir quickly, and enable them to stop in the afternoon. The third engine is quite separate and independent, and kept as a reserve in case of accidents to the others; each pump will throw about 144 to 150 gallons every stroke.

There are six boilers, each about 8 feet diameter and 24 feet long; two only being used for one engine.

The banks of the swamp are piled round where necessary, and at the lower end is a waste weir 8 feet wide, and a safety weir with flood gate about 8 feet wide, which can be lifted in time of heavy floods;—the weirs are built of solid masonry in cement, laid on a sandstone rock bottom, the outfall of the safety weir being planked over for about 20 feet; the salt water at high spring tides flows against the outside of the floodgates.

The main delivery pipe from the engines to the reservoir is 30 inches diameter inside, and from 1 inch to 1 1/8 inch thick; its course is nearly straight and its length about 4 1/2 miles.

At Crown-street, Surrey Hills has been excavated out of the hill, the reservoir, which will hold about 3 1/2 million gallons, is 20 feet deep, lined with English bricks, (no clay being obtainable near Sydney fit for the purpose,) laid in cement and backed by puddle.

The walls are upright, and the reservoir is divided in the centre by a wall, built up to about 3 or 4 feet below high-water level: the whole is arched over with brick arches, covered with gravel and soil, and sown with grass, the area on the top being used as a store yard for pipes, &c.

From this reservoir the pipes proceed to the top of a sandhill, near Botany Street, a further elevation of 76 feet or of 216 feet in all; and terminate merely in an open month, from which the water is pumped twice a day, each time for about 20 minutes, the sluices leading to the reservoir, being shut meanwhile;—during this time those persons who dwell on the higher levels must obtain their half-day's supply.

In the 30-inch main are three check valves of vulcanised India-rubber, 1 inch thick; at 30 feet, 80 feet, and 200 feet elevation, to check the tendency of the water to flow back, and to take the weight in a measure of the engines, and ease the concussion which occurs at every stroke.

The main pipes in several places on low ground are banked over with earth instead of being sunk in the ground to the required depth, in some places they are roofed over with wood. When crossing small streams they are held up by means of iron straps secured to strong wooden frames.

Where an opportunity occurred of observing the main pipes, I noticed that they were socket-pipes turned and bored at the ends, and requiring only a little tallow and whiting to joint them.

The elevation of the reservoir is sufficient to supply nearly all the thickly inhabited portions of Sydney with water, even in the upper streets, and, on the completion of the second reservoir, for which, I believe, a site has been chosen, all parts of the city will receive a constant supply.

The details of the street mains, house-services, street-watering apparatus, and fire-plugs, are much the same as those in Melbourne, which will hereafter be more fully described.

The streets in Sydney are well supplied with drinking places, the pipes for which are attached either to the cast-iron lamp-posts, or to cast-iron pillars erected for the purpose; many of these have also troughs for horses.

The charge for the supply of water in Sydney is according to the number of rooms in the house, and the present charge per annum is five shillings per room.

The water is supplied as it is pumped from the swamp, only passing through the reservoir, but it is not filtered in any way: nevertheless it is clear and tasteless.

Whilst in Sydney we took the opportunity of inspecting a dam of masonry built near Paramatta, a town about 14 miles from Sydney, for the purpose of impounding the water in a narrow rocky gully, and from thence obtaining a supply for Paramatta and its neighborhood.

Although the dam has been completed for several years, it is unfortunately the only part of the scheme that is, as so as want of funds apparently prevents the completion of the remainder of the works.

The dam is a very beautiful solid piece of work, of freestone blocks, laid in cement, and is built in the form of a horizontal arch, the ends abutting against the rocky sides of the gully. It is about 220 feet long, 30 feet high, and about 9 feet wide at top, and 25 feet wide at bottom, and has two cast-iron dis--charge pipes through the bottom of it, fitted with sluice valves, and ready for the connection of the main pipes.

The cost I have heard stated at £15,000.

This method of constructing dams I have seen strongly recommended by some engineers, and where the sides are rocky and the width of the valley small, I think it must answer well, forming a really permanent structure. Having had in view the application of this principle in connection with Nelson Waterworks, I was pleased to be able to inspect a practical example of it.

MELBOURNE WATERWORKS.

These were completed December 31st, 1857. The water is supplied from the Yan-Yean Reservoir, situated at a distance of about 19 miles from the town, measured along the line of pipes.

The reservoir consists of a flat valley in the Plenty Ranges, across the mouth or lower part of which a dam has been constructed, more than half a mile in length (1,053 yards), and about 31 feet in perpendicular height: thus impounding an area of water of above 1,400 acres, at an elevation of 640 feet above the sea level.

Besides the natural drainage from the basin formed by this valley and all its tributaries, there is another source of supply provided from the River Plenty, which flows on the other side of a range of hills bounding the first named valley.