In 1856, the greatest average amount used was 13,284,007 gallons, in December. The least was 10,377,865 gallons, in May. The daily average for the whole year was 12,048,964 gallons. During the year water has been wasted from the Lake, in various months; in all, 69 days. The rain gauge kept at the Lake shows the total fall to have been 40.8 inches during the entire year. No account of the waste from the Lake has been kept, because the temporary dam before spoken of had become useless for this purpose, and because the arrangement of the outlet dam, as originally constructed, did not permit of measurements being kept with any degree of accuracy at it.. The new dam, when finished, with its wide over fall, will obviate this difficulty. From the above observations and measurements, it would seem that there could be no doubt that Lake Cochituate could be made to furnish an average daily supply of 16,000,000 gallons, or even a greater amount, by storing all its waters, one year with another. The precise amount of expense necessary to accomplish this, can only be determined by surveys to be made hereafter. The amount of supply which may be added to it, by taking other ponds and streams, is also a matter for determination hereafter. The Conduit. On the 4th of February a portion of the embankment, over the conduit, near Morse's Pond, was washed off by the pressure of the water through an old crack in the conduit. It was temporarily repaired at the time, and in April it was thoroughly repaired. In July, about four hundred feet in length, of the bottom of the conduit in Newton Centre, was repaired, and is now in good condition. During the coming season it will be necessary to repair about fifty feet in length, near Webber's barn,.in the third section; about three hundred feet, near Knowles's road, in the same section; and about two hundred feet in length, near Morse's pond, in the first section. Several examinations of the conduit were made during the season. No new cracks were discovered. It was thoroughly cleansed in July, between Charles River and Brookline Reservoir. The form of the conduit is, as is well known, an egg-shaped oval, with a clear height of 6 feet 4 inches, and greatest width 5 feet, the largest end being down. The original estimates of its flow, as made by Robison's formulæ, corrected by observations on the flow of the Croton Aqueduct, gave, for a depth of 3 feet 10 inches, 8,305,000 wine gallons in twentyfour hours; and for a depth of 4 feet 4 inches, a flow of 9,430,000 gallons in twenty-four hours. It will be observed that the greatest depth then calculated for the water in it, left two feet of clear space in the conduit, above the water. From all previous experience, it was judged that it would be unsafe to fill it any nearer full, and it, therefore, in its estimated flow, partook of the nature of a canal, covered over only for the purpose of keeping impure matters from the water, in its course to the City. The conduit was built with American hydraulic cement. It has been repaired in the quicksands, and some other portions, by the use of Portland (English) cement, and is now, in such places, quite as strong as in any other part of it. Instead of having water flowing in it, at a depth of only 4 feet 4 inches, it has been filled entirely full, and it has had a head on it, at times, above its top, of over two feet, thus making it in effect a pipe. When the repairs are made, which are suggested above, with some additions to the thickness of some parts of the embankments, there can be no doubt that it can, with perfect safety, have such a head put on it as will cause it to deliver 20,000,000 gallons daily, in Brookline Reservoir. The pipe chambers at Charles River were designed for three pipes. Two only have as yet been laid. These two have sufficed thus far; when the third is laid, with the additional head on the conduit, it is clear that we shall have an increase of more than fifty per cent. over the delivery of the present ones. If the incrustations still continue, they may be readily cleansed, and restored to their original capacities at slight The two large meters have been removed during the past fall, from the Brookline Gate House. They were found not to answer the purpose for which they were designed. There is a small leak in the Gate House, which may be repaired in the spring, now that the meters are out of the way. Structures. There are some signs of settlement in the apron way of the small Gate House, at the end of the conduit, at Brookline Reservoir. With this exception, and the leak in the Gate House, all the structures on the line of the works are in good order. Raising Pipes on Tremont Street. When the pipes were first laid in the City, Tremont street, south of Dover street, was at a very low grade, and all the pipes laid there, at that time, were laid at the usual depth below the surface. Since then the grade has been raised several feet, and all the pipes laid there since, have been laid at the usual depth below the new surface. Many houses have been built, within the past year or two, on the street; and, it appearing probable that it would very soon be all built upon, it became a matter of importance to raise that portion of the 12-inch pipe which was at the lowest grade. In doing this it became also necessary to raise those 6-inch pipes branching from it to the side streets. All the 12-inch and part of the 6-inch pipes were at a depth, generally, of twelve feet below the surface. Whenever a service-pipe was laid, great trouble was experienced by caving in, endangering the lives of the workmen, as well as being extremely expensive. It was, therefore, determined by your Board to raise the pipes, and 1,851 feet of 12-inch, and 844 feet of 6-inch pipes have been raised. Average Monthly Heights of Water in the Reservoirs at Brookline, Beacon Hill, South Boston and East Boston, 1851-1856. NOTE.-The above average heights are given in feet, and parts, above marsh level. Maximum high water in the Brookline reservoir is 124.6 feet above |