this way it was kept in a tolerably safe condition for use under pressure. For want of such constant attention and repairs during late years, it has deteriorated considerably, and is not now so safe for such use as formerly.

Each time that it is drawn off, several hours are required to empty it and several more to fill it again; also a large volume of water is wasted. If it could be drawn off in sections much time and water would be saved, as many portions of its length do not require frequent examinations. A gate at Grantville waste-weir would be of great service in this respect, and, besides, would afford a ready means of stopping the flow should any accident happen near Charles river, the point where the chief danger exists. I therefore recommend that such a gate be provided.

When the volume of flow is large there is a loss of head or fall, in passing it through the syphon pipes, of one foot and upwards, and as the entire fall from the lake to Chestnut Hill reservoir is only about 4 feet, this loss at Charles river materially diminishes the capacity of the conduit. This loss is not of much consequence when the volume of flow is not greater than 15 or 16 million gallons per day, but I have estimated that when the conduit is under a 4-feet head a gain of about 1 million gallons per day would be made by the addition of a new siphon pipe 36 inches in diameter. The cost of the pipe (if of cast iron) and labor of laying, etc., would be from $20,000 to $25,000, and in case the city take possession of the Sudbury river and use it for the next few years as a supplement to the Cochituate supply, by turning a portion of its waters into the lake, it will be advisable to have such a pipe laid.

As a purely precautionary measure, material for about 500 feet of wooden flume has been bought and fitted, and is stored at Chestnut Hill, ready for use in case of an accident to the conduit that shall destroy the masonry. It is hoped

and expected, however, that it will never be used for the purpose for which it is kept.

New gauges (float) for giving the height of water in the conduit have been put in along its line during the past season, and observations can now be taken much more readily and accurately than formerly. The record of these gauges is used in computing the daily consumption of

water.

LOW SERVICE RESERVOIRS.

The tables on pages 31-33 give the monthly and yearly average heights above tide marsh level, of the water in the several reservoirs.

The average height, for the year, of the Chestnut Hill reservoir, has been 120.40 feet, or 1.06 feet less than in 1872.* This is due to the increase of consumption. The top of the conduit where it enters the reservoir is at elevation 123.50, and high water-mark of the reservoir is 124; hence, as the water in the latter is drawn down, the delivery of the conduit is increased. Within certain limits this fluctuation of the water surface acts as a regulator to equalize the delivery of the conduit with the city consumption.

Two new sluice-gates, made at the works of the Boston Machine Co., have been put in place at the lower or effluent gate-house, to shut off or regulate the flow in the distributing main.

The need of gates at this point, that can be quickly operated, has been felt ever since the reservoir was first put into use; in fact, in building the gate chambers provision for sluice-gates was made. These have been designed with special reference to easy and rapid movement. One man can fully open either of them in less than four minutes,

* The zero of the new gauge is .18 of a foot higher than that of the old gauge.

and they close by their own weight in rather less than twenty seconds, settling to, their seats quietly and without shock.

The openings are 48 inches square and the movement is vertical. When in motion they are each carried on three pairs of wheels, twelve inches in diameter; thus changing the sliding friction of gates, made in the usual manner, into rolling friction. The seats are not exactly parallel to the gate frame, being inclined slightly from the vertical, so that when the gate is closed, the gate face and seat are in contact and the wheels are lifted a fraction of an inch from their tracks.

Vertically over each gate is a water-cylinder fitted with a piston 8 inches diameter and 4-feet stroke. The pistons are moved by a force pump fastened to the floor of the house. The gates can be held in any position by means of a friction clutch applied to the gate rods and operated by a hand wheel.

If it should be thought desirable, they may be made to close themselves, by the tripping of a weight, in case of an accident to the distributing main which shall materially increase the rate of flow in the pipe; such an accident, for instance, as happened March 15, 1872.

A float gauge, to denote the height of water in the reservoir, has been set in this gate-house.

The average height of water in the Brookline reservoir has been 119.91 feet during 1873, or 1.64 feet less than in 1872* and 0.49 feet less than in the Chestnut Hill reservoir.

A float gauge has been set at the Brookline gate-house, thus making a complete set of float gauges, referred to a common base (tide marsh level), from the lake to the reservoirs.

The Beacon Hill, South Boston and East Boston reservoirs, though kept partially filled with water to be used in case of necessity, have been almost constantly shut off from the street pipes for the past year.

* The zero of the new gauge is .08 of a foot higher than that of the old gauge.

DISTRIBUTING SYSTEM.

Considerable work has been done during the past year in extending the street pipes, more particularly in the Highland and Dorchester Districts, and important changes have been made in the old system of distribution, especially in the city proper. Many of these changes were recommended in the last annual report; others have been marked out in special reports made in response to orders of the City Council or of the Water Board, and others still have been suggested by the experience of an inadequate supply at certain points, either for fire or other purposes.

In all 129,520 feet, or about 241⁄2 miles, of pipes, of various sizes, were laid in 1873.

Early in the season plans and estimates were made for repiping the "burnt district," and an appropriation of $85,000 for this purpose was made by the City Council. This work is now finished. Nearly all the streets in this district were re-piped with 12 and 8-inch pipes in place of 6-inch, and the plan required all the old tuberculated pipes of small diameter to be taken up, to make room for new pipes coated with coal

tar.

The new system has a capacity of delivery several times greater than the old, even if, for the latter, no deduction for tuberculation be made, and is provided with Lowry hydrants placed at distances apart never exceeding 260 feet, and generally falling much below this. In place of 80 of the old 3inch hydrants, 113 Lowry hydrants with 9-inch barrels have been substituted. The former accommodated but one steamer; the latter will accommodate four; hence it will be seen the facilities for extinguishing fires have been very largely increased. The changes made have given an improved head or pressure throughout the district.

Aug. 16, 1873, a report (City Doc. No. 112) was made in response to an order requiring the Water Board "to con

sider and report to the City Council, as soon as practicable, what alterations in, and additions to, the present system of water pipes and hydrants would be required to render them of such capacity as would afford an adequate supply of water for all necessary purposes," etc.

In the report it was recommended that certain changes be made in the old system, by laying new and enlarged submains and feeders to the smaller pipes, by uniting the smaller pipes at many of the points where they cross, and by setting Lowry hydrants at the intersections.

The estimated cost of this work was $389,000.

The City Council authorized the Board, last fall to contract for 200,000 dollars' worth of pipes, to be delivered in the spring and used for the purposes recommended, and accordingly contracts for about 3,500 tons were made. The pipes are now being rapidly delivered and laid, and the old hydrants, of small calibre, removed in laying them, are replaced with those of the Lowry pattern.

During last year and to May 1st of this year, the following lengths of 16, 12 and 8-inch pipes have been laid in place of smaller sizes removed.

4,848 lineal feet of 16-inch in place of 6-inch.

186 Lowry hydrants have been set in the city proper.

A report was made, by order of the City Government, upon the cost and expediency of building street reservoirs, and the Water Board was subsequently authorized to build these reservoirs at such points as should be selected by it and the Fire Department.

In July plans were prepared for a syphon at the Doverstreet draw, for the South Boston high-service main. The pipes for this work were not received till late in the fall. The syphon was successfully lowered into its place Dec. 24.