JOSEPH P. DAVIS, ESQ., City Engineer:

DEAR SIR: Entered the conduit at lake at 9.15 A. M., Oct. 12th.

For a long distance the bottom is very sandy, and the sides are covered with a substance resembling sponge. There are no cracks, however.

We reached Dedman's Brook at 11.45, and re-entered the conduit at 1.15. At station *160 is a crack in top arch. 169 slight crack, also at 179 and 180.

The conduit so far from Dedman's Brook is very clean.
At 182 and 3 is a crack about inch wide.

*228 to 230, slight crack.

247 and 8, crack in top arch quite large.

254, bottom quite muddy.

*255 to 57, crack, also at *259.

Between 272 and 3 is a large crack, that has been repointed,

but has not started.

274, quite a crack in several places.

284, muddy again.

*292 to 6, small cracks.

298, muddy.

13 to 14, crack, which looks as if it had spread where it was repointed, and water drips through; sand in bottom, also.

*15 to 16, quite a crack in top.

*17 to 18, large crack; also sandy.

Reached Grantville Waste Weir at 4.05, which is Station 491. Conduit very clean.

Between *51 and 2, slight crack.

107 and 91⁄2, crack that was repointed; has started, espe_ cially at 109.

Reached Lower Falls, Station 111, at 5.10.

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SUNDAY, Oct. 13th.

Entered conduit at 10.35.

142-3, little sandy.

*160, each side of man-hole is a crack.

163-4, sandy.

Between 174 and 80, some moss on each side of conduit.

196-7, crack.

216 to 2181, several bad cracks in top and on left.

Reached Newton Centre, Station 9, at 12.50; left again at

1.20.

*50 to 52, bad cracks. Conduit very clean.

Reached ventilator at 2.17; left again 2.40.
*861, crack on right.

88 to 90, considerable fungus.

93, crack on right.

*103, crack in top.

1081-110, several cracks, been repointed, not started.

*115 to 117, crack.

118, crack on right.

119-1241, several bad cracks on each side and top. Repointing is all right.

Bottom of conduit very rough.

125 to 261, slight crack.

*128-9, crack in top.

Reached intermediate gate-house, 3.15.

A statement of the condition of the grounds and structures, pertaining to the lake and conduit, will be found in the report of Mr. Stanwood, Superintendent of the Western Division. The keeper's house at the lake is in a bad state, and either it should receive thorough repair, or a new one should be built.

RESERVOIRS.

The monthly and yearly average heights above tide marsh level of the water, in the several reservoirs, are given in the accompanying tables on pp. 44-46.

It will be seen that the average height for the year has been the same in the Chestnut Hill, as in the Brookline Reservoir, and greater by of a foot, than the heights in the latter during 1871.

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The Beacon Hill and South Boston Reservoirs are not now kept in open communication with the distributing system, and therefore the heights of water in them no longer indicate the pressure upon the street mains in their vicinities. The only useful purpose these reservoirs serve at present is to store a quantity of water for use in case of fire, or of accident to the mains which supply the districts about them.

The Beacon Hill Reservoir has too high an elevation to be of use in connection with the low-service distribution, and there appears to be no good reason why it should not be abandoned, provided the proposed one upon Parker Hill be built, as the latter will command the Beacon Hill district, and insure an adequate supply for fires.

The South Boston Reservoir is also located too high to be of much use in connection with the low-service of its district, but as it stands upon a common or park, and its maintenance is inexpensive, and as it will serve to hold in store a consid erable quantity of water, for use in emergencies, such as a break in the supply main leading to South Boston, it probably will be thought best not to remove it.

The East Boston Reservoir has been thrown out of service during the latter half of the year, and that section of the city, supplied under the much greater head of the Charlestown works.

DISTRIBUTING SYSTEM.

The distributing pipes have been largely extended during the past year, more especially in Dorchester and Roxbury. The total amount of cast-iron pipes laid in 1872 is 17.8 miles.

The work of connecting Telegraph Hill, in South Boston, with the 12-inch high-service main in Washington street, Dorchester, was finished early in the year. The connection consists of a line of 12-inch pipes, laid through Bowdoin and Hancock streets, and of the new 20-inch low-service main, leading through Dorchester avenue and Dorchester street to Telegraph Hill.

The use of the 20-inch main for this purpose requires the supply to the South Boston low-service to be kept up through the single line of 20-inch pipe in Dover street. These pipes were laid when the Cochituate works were built, and are not protected by the tar coating now used.

Beyond question they are badly tuberculated, and are probably reduced in capacity of delivery, so as to be not much more than equivalent to 16-inch coated pipes.

The population of South Boston is not far from 40,000, and that it may be properly supplied with water, and as a safeguard in case of accident to or repairs upon the Doverstreet pipes, a new main should be laid, or the Dorchester-avenue main should be returned to its original purpose, and a new main, of smaller diameter, provided for the highservice.

Pressures recently observed during the morning hours, at the hydrant near the corner of E and Seventh streets, show a loss of head, of about 28 feet, between that point and the Brookline Reservoir, and a large portion of this loss must be due to the friction in the Dover-street main.

In the report of this department for last year, Mr. Crafts recommended that a new high-service main be laid from the

pumping works to Beacon Hill, and the old 30-inch main, now supplying the Beacon Hill high-service, be used to aid in the supply of the low-service of the city proper. I fully endorse his recommendation, and would urge that it be acted upon at an early day.

To ascertain the losses of head at the end of the large supply mains, and in the business portion of the city, Mr. Jones, Superintendent of the Eastern Division, has taken gauge readings from the 40-inch main near its junction with the 36inch main (reduced to 30 inches) on the Common, and also at the hydrant corner of Broad and Milk streets.

From these it appears that during the morning hours — or from 8 to 11 o'clock - the loss of head on the Common is from 14 to 17 feet; and that at the corner of Broad and Milk streets, during the same hours, is from 30 to 37 feet. It will be noticed that the loss between the two points at which the readings were taken (the observations were simultaneous) is nearly 20 feet, or greater than that between Brookline Reservoir and the Common. This indicates the need of greater capacity in the branch-mains feeding the easterly portion of the city.

All the territory lying to the north and east of Cambridge, Court, Tremont, and Essex streets is chiefly supplied from the single 30-inch main, in Boylston street; now the application of the 30-inch high-service main to the low-service distribution, as recommended, will give a new and very important connection between the Common and that territory, and materially improve the pressure where improvement is much needed.

If it should not be deemed advisable to now incur the expense of laying the new high-service main the entire distance between the pumping station and Beacon Hill, that portion of it between the Common, near Boylston street, and the hill, can be laid this season, and thus release enough of the 30-inch main to give the desired connection between the Common and Haymarket square on the low-service.