It will be observed that the lowest stage of this reservoir during the fiscal year was 0.93 foot higher than the lowest stage during the preceding fiscal year and 3.63 feet higher than during the year before that. With the exception of the intensely cold period from January 27 to February 3, 1897, the water level in the reservoir at no time fell below 145.6 feet above datum.

This marked improvement in the normal level of the reservoir arises from three causes: First, raising the dam at Great Falls; second, removing deposits from the conduit, and third, putting the Dalecarlia reservoir into service. From the spring of 1888 until July 27, 1895, this reservoir was out of service, and a sudden demand upon the comparatively small supply stored in the distributing reservoir affected its level much more than at present, when it is connected with the Dalecarlia Reservoir. In addition, when the latter reservoir was out of service the water was carried around it by means of a by-conduit, which for 625 feet of its length has a diameter of but 8 feet, and serves to throttle the flow materially. Since this reservoir has been put in service no throttling occurs and the flow is increased.

THE CONDUIT AND THE BY-CONDUITS.

With the amount appropriated by the act of March 2, 1895, the entire conduit and both by-conduits had been thoroughly cleaned during the preceding fiscal year for the first time since their construction, and 8,946 cubic yards of deposit had been removed therefrom. During the operations connected with the removal of these deposits a large number of longitudinal cracks were discovered and were carefully plastered up with cement mortar. A detailed description of all operations connected with the removal of deposits and a table showing the location of the cracks are given in Appendix B B B of the Report of the Chief of Engineers for 1896.

During the months of May and June, 1897, all deposits were removed from the entire conduit between Great Falls and the distributing reservoir, and from the by-conduit around the distributing reservoir, and the interior of both the conduit and by-conduit was carefully scraped and swept. About 165 cubic yards of deposits were removed between Great Falls and the Dalecarlia Reservoir, and about 5 yards between the two reservoirs. An attempt was made to clean the by-conduit around the Dalecarlia Reservoir, but when it was entered for this purpose the north connection, which has been in particularly bad condition for several years, was judged to be too unsafe to warrant the risk of keeping men at work in the by-conduit.

This by-conduit, which is 2,730.5 feet in length, and is a useful part of the aqueduct system, was constructed during the civil war, when the aqueduct was under charge of the Department of the Interior, but the rubble masonry used in its construction was of very inferior quality, and it has been in a leaky condition for many years.

For a part of its length it is located too near the reservoir, the banks of which in this vicinity are very steep, and should it ever become necessary to draw off all of the water from this reservoir there is very grave danger that, relieved of the water pressure from the reservoir, portions of the bank between the by-conduit and the reservoir will slip into the latter, as has been the case on two occasions heretofore, and breaks in the by-conduit will result. To afford even a fairly efficient service the entire north connection and the portion of the by-conduit adjacent to it must be rebuilt, and an estimate for doing this work is submitted in the proper place.

The deposits removed during the present fiscal year were confined almost exclusively to the seven unlined 11-foot tunnel sections and to the thirteen 9-foot 9-inches enlarged brick and masonry sections.

A careful inspection of the conduit, made while the work of remov ing deposits was in progress, shows that none of the cracks plastered up during the preceding fiscal year have opened, and that no new ones have developed. A new board walk was constructed in the tunnel leading to Wasteweir No. 2.

THE CONDUIT ROAD AND ITS FENCES.

For use in repairing the Conduit road 1,714 cubic yards of flint stone were purchased during the fiscal year. The following quantities of stone were crushed and spread upon the Conduit road at the localities mentioned below:

Forty-five cubic yards of flint stone near the distributing reservoir; 356 cubic yards of blue stone near the Dalecarlia Reservoir, and 999 cubic yards of flint stone between Cabin John Bridge and Bridge No. 3. The breaking of the crusher and the low state of the annual appropria tion prevented the crushing of the remainder of the flintstone purchased. Extensive repairs were made to the dirt road between the Club House and Great Falls, a distance of about 2 miles. General repairs were made to all other portions of the road, ditches were cleaned, bushes cut down, slopes trimmed, and deposits removed from culverts.

A new painted board fence was erected on each side of the road at the northwest approach of Cabin John Bridge.

All of the guard fences on the embankments along the Conduit road have been extensively repaired and whitewashed.

Year by year the travel on the Conduit road, which is the most beauti ful driveway in the vicinity of Washington, increases, and with it increases the amount of road metal necessary to keep the road in repair, until at the present time the cost of repairing this road entails a most serious drain upon the very limited annual appropriation for the maintenance of the Washington Aqueduct and its accessory structures, amounting during the past two years for the surface repairs of the road alone to more than 12 per cent of the total annual appropriation for the Washington Aqueduct during that period.

Although the Conduit road is the property of the Washington Aqueduct, it is so extensively used as a public driveway that it does not seem fair to charge the annually increasing cost of maintaining it entirely against the appropriation for supplying the District of Columbia with water, thereby reducing the amount available for use on other parts of the system.

Although much appreciated in its present condition by the thousands of persons who use it, the condition of the road would be greatly improved if a fixed amount were appropriated annually, exclusively for supplying and spreading road metal upon the road, the repairs to culverts, ditches, bridges, etc., being essential to the safety of the Washington Aqueduct, to be paid as at present from the regular appropriation for the maintenance and repair of the Washington Aqueduct. An estimate of the annual cost of supplying and spreading road metal upon the Conduit road between Georgetown and the Club House is accordingly submitted in the proper place.

THE MAINS.

The trunk mains, aggregating 21 miles in length, which lead from the distributing reservoir and supply the distributing system of street mains, were laid by the United States and are under the control of this

office, but the distributing mains were laid by the District of Columbia and are under the care of the Commissioners of the District.

By act approved June 11, 1896, $5,000 was appropriated for inserting air valves and blow-off valves in the 36-inch and 30-inch mains. The project for this work was approved on June 26, 1896, and operations were commenced in October, 1896, and completed in February, 1897. With this appropriation air valves and blow-off valves with the necessary casings, covers, masonry work, etc., were inserted in the 36inch and 30-inch mains at the following places:

12-inch blow-offs in the 36-inch main.

One at New Jersey avenue and L street NW.

S-inch air valves in the 36-inch main.

One in vault at distributing reservoir.
One at Thirty-fourth and M streets NW.
One at Thirty-second and M streets NW.
One at Twenty-fourth and L streets NW.
One at Eighteenth and L streets NW.
One at Eleventh and L streets NW.

12-inch blow-offs in the 30-inch main.

One at Twenty-first and K streets NW.

One at Sixteenth and K streets NW.

One at Massachusetts avenue between Fourth and Fifth streets NW.
One at New Jersey avenue and K street NW.

3-inch air valves in the 30-inch main.

One in vault at distributing reservoir.

One at Thirty-fourth and M streets NW.

One at Thirty-second and M streets NW.

One at Pennsylvania avenue between Twenty-third and Twenty-fourth streets NW. One at Nineteenth and K streets NW.

One at Thirteenth and K streets NW.

One at Third street and Massachusetts avenue NW.

One at New Jersey avenue and I street, NW.

One at New Jersey avenue and B street NW.

From the annual appropriation for maintenance and repair of the Washington Aqueduct, a 12-inch blow-off was placed in the 48-inch main at New Jersey avenue and L street NW.

The air valves and blow-offs were all inserted by the use of the A. P. Smith tapping machine without the necessity at any time of shutting off the water from the mains.

In doing this work the pieces cut out of the mains indicated their condition as regards "tuberculation," which was as shown in the following table:

From this it will be observed that the interior of the 30-inch main is in such poor condition that the velocity of flow through it must be greatly retarded by friction.

During the construction of the large intercepting sewer by means of a tunnel under the east abutment of the M Street Bridge over Rock Creek, it was observed that the street above the tunnel was settling, and with it the 48-inch main, one joint of which rested rigidly on the stone abutment of the bridge, causing slight leakage to develop in the joints of the main. These were promptly calked, and to prevent trouble from possible future settlement the main was supported by two braced iron girders resting upon concrete piers. This work was done at the expense of the District of Columbia, as the support was rendered necessary on account of the construction of the intercepting sewer.

An 8-inch cast-iron drain was laid from the valve vault of the 36-inch main near Foundry Branch to the branch, a distance of 60 feet.

A new platform was built around the 48-inch gate in the vault at New Jersey avenue and L street NW.

A break in the 24-inch main on K street, between Eighth and Ninth streets NE., was repaired, and leaks in the mains at the following points were discovered and stopped by recalking the joints:

48-inch main.

Leaks in several joints on M street near Thirty-second street.
A leak in the joint on M street near Twenty-sixth street.

Leaks in several joints under the M Street Bridge.

Leaks in several joints in the east abutment of the M Street Bridge.

A leak on M street near Thirty-second street.

Leaks in the east abutment of the Pennsylvania Avenue Bridge.

All pipe vaults have been cleaned and valves have been oiled and worked regularly.

Section 1803, Revised Statutes, forbids the tapping of any main laid by the United States in the District of Columbia except by permission of the Chief of Engineers, United States Army.

Upon recommendation of Col. George H. Elliot, Corps of Engineers, in letter dated December 31, 1894, concurred in by the Chief of Engi neers and approved by the Secretary of War, general authority was granted to the Commissioners of the District of Columbia to tap all the United States mains in the District of 12 inches in diameter and under at their pleasure, with the exception of the 10-inch main in Georgetown between its valve just north of M street and the Rock Creek Aqueduct Bridge at Pennsylvania avenue, the 12-inch main on the Conduit road between the distributing reservoir and Foxhall Hill, and the 12-inch main on the Canal road.

Permission was given by the Chief of Engineers to Mrs. Ellen O'Neil to tap the 12-inch main with one 1-inch tap on the Conduit road in front of lot F in Harlem for a building erected on that lot, and to Messrs. S. S. Shedd & Bro., for Mrs. H. Semken, owner, to tap the 30-inch main with one 1-inch tap for the supply of premises No. 1407 K street, and

by the officer in charge of the Washington Aqueduct to the Commissioners of the District of Columbia to connect a fire hydrant on Massachusetts avenue between Fourth and Fifth streets with the 12-inch blow-off on the 30-inch main.

THE BRIDGES.

All of the bridges are in excellent condition, with the exception of the wooden flooring of the roadway over the Pennsylvania Avenue Bridge and that of the wooden bridge across the spillway of the Dalecarlia Reservoir, both of which are considerably worn and will soon require renewal.

The roadway of Pennsylvania avenue, which in the vicinity is 53.5 feet in clear width, is contracted on the bridge to a clear width of but 17 feet, and as drivers are required to walk their teams while passing over the bridge, a congestion of travel results during the busiest hours of the day, causing delay and annoyance, as there is not room for one team to pass another, and consequently the speed of all teams on the bridge moving in the same direction is limited by that of the team in front. Especially is this annoyance felt by the thousands of bicycle riders who daily pass over the bridge and who, unless experienced riders, are frequently forced to dismount and lead their bicycles over the bridge, the rate of progress of the teams blocking the roadway ahead, being too slow to allow an inexperienced rider to maintain equilibrium. In addition, the sightly appearance of the avenue is much injured by the extreme contraction at this point.

This bridge, the property of the Washington Aqueduct, is very graceful in appearance and is unique among the bridges of the world, in that the roadway is supported upon arched ribs formed by two 48-inch cast-iron pipes, through which flows at least half of the water consumed by the city. It would seem therefore that any plan to widen the bridge should preserve both the graceful form and the distinctive features of the bridge.

A Board of Engineers, constituted by Special Orders No. 8, February 2, 1877, and composed of the following officers of the United States Corps of Engineers, Bvt. Maj. Gen. Z. B. Tower, Bvt. Maj. Gen. H. G. Wright, and Bvt. Maj. Gen. Q. A. Gilmore, was assembled to examine into the propriety of certain proposed modifications of this bridge. This Board after due consideration of the matter reported as follows:

It would, in our opinion, therefore, better accord with the position on Pennsylvania avenue and with the general character and architectural effect of other aqueduct structures to widen this structure, without changing its design, by the addition of two arched iron ribs similar to those of the present bridge and by widening the abutments.

These two arched ribs should be made about as heavy as those of the present bridge. As the previous discussion shows the latter to be abundantly strong without the truss work, in the new construction the greater portion of the whole weight of the bridge could be thrown upon the added arches, not used as water pipes. We regard the arch as far more sightly, beautiful, and architectual than the truss, and therefore more suitable for this position.

On April 26, 1877, the late Gen. Thomas L. Casey, United States Corps of Engineers (retired), then in charge of the Washington Aqueduct, was requested by the Chief of Engineers to investigate and report upon "the present and prospective use of that bridge as a highway, etc." This he did on July 19, 1877, his report concluding with the following opinion:

I am further of opinion that the present and prospective interests of the citizens of Washington and Georgetown do demand an increase in the width of the roadway