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This range of hills has been pierced by a tunnel, and beyond the tunnel a channel has been cut two and a half miles to the River Plenty. By means of this channel the waters of the river are brought into the reservoir when clear and pure, but shut out when muddy and impure by floods, by means of proper flood-gates, &c.

The water in the reservoir is thus continually changed, as besides what flows off to supply Melbourne, large quantities are let off by the discharge pipes provided for that purpose, through the bottom of the embankment. The supply of water thus provided may be said to be almost boundless, as a whole week's lavish consumption of water would only reduce its level in the reservoir by about two inches.

The width of the embankment, which is of earth and clay, containing a puddle wall in the centre, is at top about 20 feet and at the bottom about 170 or 180 feet; the outer slope is 2 to 1 covered with turf, and the inner slope 3 to 1 pitched or faced with stone from top to bottom grouted with cement. The puddle wall in the centre is about 10 feet wide at top and 30 feet at bottom.

The size of the main pipe as it leaves the reservoir is 33 inches diameter inside, reduced at certain distances to 30 inches, then to 27 inches, and to 24 inches when it arrives in Melbourne.

It is one inch thick all through, and it is constructed with socket joints, made water-tight in the usual way by pouring in melted lead, a ring of hempen rope or spun-yarn being first caulked in all round.

This kind of joint is used throughout all the mains, large and small.

At Preston, a distance of about seven miles from Melbourne, the main is made to discharge the water, at pleasure, into a service reservoir 300 feet above the sea level, and capable of containing about 13,000,000 gallons.

This reservoir is dug partly out of the solid, and partly embanked, about 21 feet deep; the outer slopes 2 to 1, grassed, the inner slopes 1 1/2 to 1 pitched with stone, the same as in the larger reservoir. The average length is about 545 feet, and the breadth 212 feet.

From this the supply for the town is usually drawn, it is not being desirable to have the full pressure due to the height of the main reservoir continually in the pipes; but the full pressure can at any time be put on, by cutting off the connection between the main pipe and the small reservoir, (for which proper provision of sluices, &c., is made,) and allowing the water to flow uninterruptedly to town the whole way.

As the main pipes approach the town, they are made to branch off into smaller mains to supply the different districts, and these are again branched off into the different streets; the street mains varying from 3 inches upwards.

In the broad streets the mains are laid on both sides, just outside the foot-paths, and in the narrow streets one main only is laid, and that in the centre; fire plugs being introduced (on both sides in the main streets) about 50 yards apart.

These are, besides being used in case of fire, made serviceable for the purpose of watering the streets, an operation carried on to a great extent in Melbourne, during dry and hot weather; so much so that the waste water, with that lost by leakage in various places, forms continual streams running all day down the open water channels on both sides of the streets.

It has a wonderfully cooling effect on the atmosphere of the town, and by removing large quantities of refuse which might otherwise lie in the streets and become a nuisance, must conduce largely to the health of the town, in the absence of a proper and efficient system of underground drainage, which, although it has been proposed, has not yet been commenced with.

The houses are supplied from the mains either through leaden pipes or galvanised iron pipes, the Government laying the pipes to within one foot of the house front, or the line of street.

A peculiar kind of cock is used under the high pressure system of supply; it consists of a brass shell very much like an ordinary water-cock in outward appearance, but containing a circular opening, covered by a flat disc, which is moved by a screw having a handle at the top; by this means the disc is necessarily lifted very gradually, and closed in the same manner, thus preventing all concussion in the pipes which would otherwise occur by a quick closing of the aperture, such as takes place in an ordinary cock. No cisterns are required in the houses, as the water is continually laid on.

The streets of Melbourne are well supplied with drinking places, mostly connected with the lamp posts, in which the supply pipe and cock are concealed and protected, and each of which is fitted with an iron ladle and chain.

There are also cast iron drinking fountains in the streets, but not in any great number; drinking troughs for horses are very numerous, in fact nearly all the hotels both in town and country have them in front of their doors.

The supply of water at such a high pressure is found to be of the greatest service in the case of fires, and as before explained the fire-plugs in the main streets are so numerous, that a hose-pipe can be attached at almost any point as close to the site of the fire as may be desired.

The effect of the water being driven against a burning house or store, with such force and velocity is described as being more to "beat out the flames than to quench them with the moisture."

Such is the certainty of success with which the "Yen Yenn," as it is popularly called, can be brought to bear on a recently discovered fire, that people do not insure their property to the extent they formerly did, and the insurance offices feel this to a serious extent.

The same apparatus is used for subduing a fire as for watering the streets; it consists of a brass pipe made like the letter T, the lower end of which can be rapidly attached to the fire plug by means of a screw, and to either or both of the heads of the T hose-pipes can be screwed in the usual way.

I had not an opportunity of inspecting the equipment of the fire-brigade, but I am told that it is being very simple, consisting principally of a large-wheeled truck fitted with a revolving reel on which are coiled the Vulcanized India Rubber hose-pipes in so many lengths already screwed together.

The supply of water to individual consumers in Melbourne is unlimited, and it is certainly used freely and almost lavishly by every one: besides this there is a considerable amount of continual waste, by the leakage of pipes and cocks in different premises, and over which constant inspection cannot be exercised.