been done under contract. The labor of the chain-gang has been utilized to great advantage in the work of repair and in the planting of trees under the direction of the parking commission, and a notable economy has been effected in the reduction of rates for day-labor of men, horses, and vehicles.

The reduction in the cost of sweeping streets and avenues and cleaning alleys, under the administration of the Commissioners, is now about $51,000 per annum.

The reduction in the cost of the clerical force and field-parties for engineering and superintendence under the direction of this office, as compared with the corresponding organization under the board of pub. lic works, was, during the progress of the work of improvement under the various contracts of the board of public works, about $156,776.28 per annum, and is now about $185,245.80 per annum. The average increase of receipts over expenditures in the public markets is now about $6,562.74 per annum.

The daily report of this date, herewith presented, shows the total expenditure since the date of my last annual report. With this is given an estimate for the present fiscal year and for the fiscal year ending June 30, 1878. Details of the expenditures will be found in the appended tables and reports.

Extract of daily report of Engineer, November 30, 1876.

6, 000 00
50,000 00
40, 000 00
4,000 00

Surveyor's office: g
Salaries of clerks employed in the preparation of assessments and examina-

Buildings: i

Erection and repair of street-lamps and gas-fixtures, under direction of this

The estimates in the foregoing table have been fixed at a minimum. The appropriations for the purposes indicated should be specific and definite, and the expenditures for repairs should be regulated by some general plan to be adhered to during the progress of the work. No estimate is made for continuing the work of improvement; but for the extraordinary repairs required in replacing the wood pavements, which are rapidly disappearing from the surface of the streets, the necessary funds should be provided for use during the next working season. The condition of these pavements is such that any attempt to repair them is a waste of time and money. The only remedy applied to them at present is to fill up the holes with gravel as they occur upon streets which are much used by vehicles, and this primitive expedient does not solve the problem in such cases, nor recommend itself to general application. The pavements must be replaced by a more durable material than wood blocks. In justice to the round-block pavements, it should be said that they have required little or no attention, and are now in fair condition, a few streets only showing evidences of wearing out, without any general indication of decay. None of these require renewal at present. The defective concrete pavements laid under the board of public works and not yet repaired require the greater part of the expenditure for repairs which is estimated for in the coming year. Minute repairs of all pavements of this class are required from day to day, and will consume the balance of the estimate. Unremitting care and prompt attention are necessary for the proper maintenance of these pavements, and will greatly reduce the cost of repairs. The necessity for a liberal provision for general repairs will appear from the following table of approximate areas of pavements, &c., to be provided for:

Wood pavement, (round block)

Wood pavement, (square block)...

Square yards.

Pennsylvania avenue between First and Fifteenth streets, N. W., and intersections, about.

Concrete pavement, (exclusive of Pennsylvania avenue between First and
Fifteenth streets, N. W.).....

734, 329 144, 016

701,376

Belgian-block pavement.

Of Neuchatel and Grahamite asphalt pavements about one-half laid; work progressing.

.....

80,000

Square yards.

Blue-rock...

Cobble-stone.

McAdam carriage-way.
Gravel carriage-way.

Alley pavements.

262, 074

Total length of county roads, 1022 miles; total length of District water-mains laid, 730,3144 linear feet, or 1381974 miles; total number of catch-basins, 2,459; total number ot manholes, 3,170; main brick sewers, from 2 feet 6 inches to 30 feet in diameter or span, 103,596 linear feet; tile-pipe sewer from 12 to 36 inches in diameter, exclusive of houseconnections, 497,432 linear feet. There are in addition to the foregoing about 41,000 linear feet of brick sewers in Washington which were constructed under the old corporation, ranging in size from 2 to 6 feet diameter or span, and in Georgetown about 16,000 linear feet of combined brick sewers and open drains, ranging in size from 3 to 8 feet diameter or span; also the old graveled streets and the alley pavements.

GENERAL CONSIDERATIONS.

It is to the maintenance and perfection of the present improvements rather than their further extension that every energy should be directed

at present. For this the restoration of defective wood and concrete pavements and the modification of some of the lateral sewerage, laid under former administrations, which is now a source of inconvenience and injury to private property, demand the earliest consideration. In the matter of sewerage a number of localities from which complaints were received have been visited, the cause of complaint ascertained, and a remedy devised, of which the want of funds has prevented an application. In general the difficulty arises from the insufficient size of lateral sewers, and the remedy is either to increase the size or to provide for surface-drainage, and keep the rain-fall out of the sewers, in whole or in part, wherever these are too small to carry it. In general, in the plan of improvement of Washington and Georgetown, and ordinarily of any city in which the surface-water is carried off by the sewers, each square is provided with a catch-basin at one or more of its lower corners which receives the drainage from the square and from one-half of the surrounding carriage-way, and this drainage is emptied into a sewer which gradually increases in size in proportion to the number of squares, the drainage of which it receives in succession. The construction of modern pavements of carriage-ways is based upon this system. It avoids all intersecting gutters to break the uniformity of its surface, and surrounds each square with a low elevation caused by the rise of the pavement from the gutter to the middle of the street, the crown of the carriage-way, which confines the surface-water of the square to the gutter which surrounds it, unless the water rises to such a height as to flow over the crown of the carriage-way, the gutters leading it to the catch-basins placed to receive it. On streets of considerable inclination where the crown of the carriage-way on the intersecting street is low, as on the streets paved with concrete or asphalt, the continuous gutter of the one street is not interrupted by the crown of the other, and unless some means be taken to prevent it the surface-water will pass the catch-basin at the corner of a square without entering, and will accumulate at some other point where the catch basins and their outlets will be required to receive and discharge the drainage of two or more squares. By taking advantage of this fact and favoring to some extent the application of the principle in laying the pavement of the carriage-way, the inlets to the sewers may be so located as to very greatly diminish the cost of rectifying errors in the dimensions of the sewers themselves.

The use of self-acting flood-valves was recommended in my last annual report, for the protection of private property against the cousequences of an overtaxed sewer, and particularly in the case of cellars below or near tide-level, in which no other remedy could be devised. The valve should be placed at or near the building-line to prevent the entrance of water from the sewer into the premises by means of the house-connection. It has been said that these automatic valves are of uncertain action and liable to get out of order, and the complaint appears to be well founded in the case of all that have been brought to my notice, which depend upon gravity, the motion of a hinge, or the accurate fitting of metal surfaces, for closing them effectually. But there was brought to my notice recently a device which impresses me favorably as a successful solution of the problem. A chamber is made, of suitable size, at the bottom of which is the outlet-pipe, and at the top, entering vertically, the inlet-pipe of the chamber, which is the inner section of the outlet-pipe. The end of the inlet-pipe is the valve-seat, against which is forced a hollow globe, of some material to be deter. mined upon. Whenever water enters the chamber to a sufficient height