should be done by contract or otherwise, as the Secretary of War might determine.

The object and plan of this improvement were fully described in my last annual report, and the work accomplished during the last fiscal year has been stated in detail in this report under the heading "The reservoirs." By means of the $60,000 appropriated for the work the main drainage tunnel under Dalecarlia hill, nearly 1,000 feet long, has been completely finished, and it has been very carefully lined with brick, exhausting the appropriation.

There remains to be done a short tunnel through the hill which lies to the east of Little Falls branch, the open channels between the three streams that empty into the reservoir, and the permanent dams across these streams. The estimate submitted is necessary for these purposes, and it is earnestly hoped that this amount will be appropriated before the close of the current session of Congress for the completion of the work.*

Storage yard.-In my last annual report I stated the necessity for a yard near the aqueduct office for the storage of articles that are necessary for repairing any breaks that may occur in the 21 miles of trunk mains belonging to the United States. The storage yard on the bank of Rock Creek, in rear of and pertaining to the aqueduct office, is entirely unsuited to the purpose. It is too low, and the route from it to the level of the street being steep and tortuous, before the very heavy castings required for these repairs could be hauled out much damage and destruction of property might be done. I quote my former remarks on this subject and renew the estimate submitted:

I have provided supplies for use in case of breaks in the 48-inch and other mains, comprising sections of pipe, curves, crosses, reducers, sleeves, etc., a heavy wagon for hauling them where needed, lifting jacks, and efficient pumps; also machinery for lowering the pipes in the trenches, and the implements and material required for handling and calking.

A portion of these supplies has been placed in a yard which I have arranged on the public land at the distributing reservoir, for use in the country portions of the routes of the mains, and the remainder for use in the city portions of these routes has been placed in a portion of Twenty-seventh street, near M-street bridge, which has been loaned for the purpose by the District government until the street is wanted for improvement.

As we shall not be able, probably, to retain this place, except for a short time, a permanent yard in the city should be purchased for use as a storage yard. It should be near this office, and at or near the grade of the street, so that the heavy castings and machinery required for repairs can be quickly gotten out.

I believe that a suitable lot can be obtained by purchase, or if need be by condemnation, for $10,000, and I recommend an appropriation of this amount for the purpose.

In my last annual report and in several previous annual reports, I called attention to several other works that in my judgment were required for the improvement, the preservation and repair of the aqueduct, and submitted estimates of their cost. No appropriations having been made for these works I renew the estimates of their cost and restate explanations of their necessity:

Widening the macadam pavement of the Conduit road.—The present macadam pavement of the Conduit road was only made wide enough (about 12 feet) to prevent the earth-covering of the arch of the masonry conduit under the road from being cut through by travel in spring, and at other times when the ground is softened by rain. The travel on the road in good weather, and especially on Sundays and other holidays, has increased so enormously that collisions are frequent. Wrecks of vehicles are often seen along the sides of the road on Mondays, and there is constantly danger of serious accidents by collision on the narrow pavement of this road.

The greater portion of the Conduit road is beyond the District line, but it and the

* Since this report was written the sum of $52,500 has been appropriated for continuing this work, leaving the amount yet to be appropriated $37,500.

strip of land through which it passes belong entirely to the United States. It is almost the only, if not quite the only, road out of the city that has not been spoiled for driving purposes by street railways. It is one of the most picturesque roads in the country, extending far up into Maryland amid the fine scenery along the Potomac, and it is the only route to the city that is available for a large number of the farmers of Montgomery County. Congress has refused to allow the road or any part of the strip of land referred to to be occupied for railroad purposes, and in its charter for a railway on private lands south of the Conduit road and parallel to it (that of the Washington and Great Falls Electric Railway) the marring of the beauties of the road was carefully guarded against, and the construction of more than one line of railway near the Conduit road was prohibited.

The macadam pavement should be widened to a width of 30 feet. The depth of the new portions should be 13 inches, including 8 inches of large stone, 4 inches of small broken stone, and 1 inch of binder. There should be a wide-paved gutter and a line of shade trees (preferably alternate lindens and tulip trees, on each side of the road, and the slopes of embankments should every where be sodded. This plan will require the widening of the roadbed at several places by adding to the width of the embankments over the culverts that pass under the aqueduct, by cutting away embankments on the upper side of the road, and by filling on its lower side.

I estimate that the cost of the work required for that part of the road that lies between the auxiliary gatehouse at the distributing reservoir and the foot of Dalecarlia hill, a distance of 13,200 feet, or about 2} miles, will be $34,500, and an estimate for it is submitted in the list of estimates. The remaining distance to Cabin John Bridge, which is the limit of the major part of the travel at present, is about 3 miles. It will probably not be necessary to extend the improvement of the road beyond this point for several years.

In addition to widening the pavement of the Conduit road as herein proposed, a width of 100 feet, or such other width as may be necessary, on each side of the road, should be purchased or condemned for the purpose of parking it, and with the additional object of controlling the land abutting on the road and excluding the liquor saloons that now exist and are increasing, and to which many of the collisions on the road are doubtless attributable.

I may remark that when the late Gen. Meigs constructed the Washington Aqueduct (it was commenced in 1853 and essentially finished in 1863) there was no road along it or in its vicinity, and the only road from Washington to Great Falls was via the Rockville road and the "River" road, which ran and now runs from Tenuallytown to the Falls; but the route over the conduit being shorter and until the hills around the Falls are reached comparatively level (the road has essentially the same grade as the conduit beneath it, viz, 9 inches to the mile, or, more accurately, 9 inches in 5,000 feet, or 0.00015), it soon attracted travel, which has been constantly increasing. Raising the masonry casings of the manholes along the line of the aqueduct.-When the water in the distributing reservoir is at its normal height of 146 feet above datum, there is a pressure of something over 4 feet of water at the crown of the conduit arch where the conduit enters the reservoir, and the water in the conduit is backed up and the crown of the arch is under pressure about as far up as Bridge No. 3, or Griffiths Park bridge, the bridge next above Cabin John bridge. I found when I uncovered the manholes along the line of the conduit for use in my inspection of its interior from Great Falls to the distributing reservoir in September, 1891, that the tops of several of the casings of the manholes below this point are below the gradient or slope of the water, so that when the manholes are uncovered it is found above the manhole covers, and in some instances more than a foot in depth above them. No harm has thus far resulted from this state of affairs, but the casings of the manholes wherever necessary (I have a record of them) should be raised above the gradient, so as to prevent the soakage of the ground around the manholes. An estimate of $600 for this work is submitted.*

Lowering the height of the cross dam in the distributing reservoir - The lower reservoir (the distributing reservoir) is divided about halfway between the influent and effluent gatehouses by a cross dam, in the middle of the length of which is a narrow cut lined with masonry, through which all the water on its way to the effluent gatehouse, where it enters the mains, must pass.

The draft through this cut is so strong that the major part of the water is drawn straight from the influent gatehouse, which is in an angle of the upper division (the settling division), to the cut, so that when the water is turbid it does not diffuse itself through the whole body of water in this division (110,000,000 gallons) as it should, in order that the greatest amount of settling be done.

Neither is the water after it passes through the cut properly distributed through the lower division, which contains about 60,000,000 gallons, for the reason that the draft from the cut to the head of the mains leading to the city from the lower end

* This work must be done before the height of the dam at Great Falls is raised.

of the division is so strong that the water all passes in a comparatively narrow stream straight to these mains, so that it also gets very little chance to settle in this division.

Now, as the upper portion of any body of water not quite free of turbidity, and in the process of settling, is the clearest, if the top of the dam be lowered far enough to allow only a thin sheet (at the present rate of consumption it would be about an inch deep) of water to pass over the dam, as was Gen. Meigs's design, we should have in each division a very effective additional means of clarifying the aqueduct water, and I believe that this improvement in the distributing reservoir being made, and the Dalecarlia receiving reservoir being improved as has been provided for in the act of March 3, 1893, there would be but rarely, if any, complaint of muddy

water.

I estimate the cost of this improvement at the distributing reservoir by lowering the cross dam at $12,500.*

Protection of the inlet to the conduit at Great Falls.-The bank of the Chesapeake and Ohio Canal, which runs parallel to the Potomac at Great Falls, and about 150 feet from it, is about 16 feet higher than the uncovered chamber, just above the Maryland end of the aqueduct dam that forms the inlet from the river to the conduit. In the flood of November, 1877, which rose at Great Falls to the height of 160 feet above the datum of the aqueduct, or 12 feet higher than the crest of the dam, the canal bank at a point opposite the inlet was washed down to the river and a part of it into the inlet. I quote from the annual report of the aqueduct for 1878:

"The masonry forming the arch of the feeder was uncovered from a point near the middle of the canal to the mouth of the feeder, a distance of 150 feet. The chamber at the head of the aqueduct was filled with stones that had formed the slope wall of the canal, and the aqueduct feeder for a distance of 300 feet was filled with débris to depths varying from 3 to 6 feet, so as to entirely stop the flow of water during the ordinary low stages of the river."

In the still higher flood of June, 1889, which rose to the height of 16 feet over the aqueduct dam, the canal bank was again washed down to the river, but fortunately the damage did not occur immediately opposite the inlet to the conduit, but from 200 to 400 feet higher up, so that the major part of the débris being left on the margin of the river and a part of it being carried over the dam, not so much filling of the inlet to the conduit was done, but, as in the flood of 1877, it was partially obstructed.

The annual report of the aqueduct for 1889 says:

"The banks of the Chesapeake and Ohio Canal above and below the mouth of the conduit were carried away and that opposite the conduit was threatened. A number of men were kept at work on this bank during the freshet, and it is believed that had it not been for the energetic work of this force and the widening and strengthening of the bank at this locality in April, great damages would have occurred at the mouth of the conduit."

It will be observed that in the freshet of 1877 not only the inlet chamber, but the conduit itself was filled with débris to a depth of from 3 to 6 feet for a distance of 300 feet in from its mouth, but, the water in the river being at a high stage, there was still waterway enough in the conduit above the débris to enable the supply to the city to be kept up. Had a complete closure of the mouth of the conduit occurred, with 12 to 16 feet of water over it, there would have been no possible way, with the torrent raging over the mouth, to remove the obstruction before the river subsided, and the water supply to the city would have been cut off.

There is no more important part of our system of water supply to be carefully guarded than the head of the conduit at Great Falls, and in order to avert dangers like those of 1877 and 1889, to which the water supply is liable in every freshet, a masonry wall should be built between the river and the canal, rising a few feet higher than the latter, and extending upriver from the mouth of the conduit as far as the limit of the Government land, and thence, at about a right angle, and still on the Government land to the shore of the river. I estimate the cost of this wall at $5,000.

Cleaning the bottom of the distributing reservoir.—The sedimentary deposits of about 20 years, within which time the distributing reservoir has not been cleaned out, have raised the bottom of its upper division (the settling division) about 9 inches, and of the lower division about 4 inches.

These deposits have diminished the capacity of the reservoir about 8,000,000 gallons, and, although it is probable that these deposits, which are mostly clay, are not deleterious to the water, they should be removed as soon as an appropriation

*This work need not be done before the height of the dam at Great Falls is raised, and the height of water in the distributing reservoir can be maintained at the constant levei of reference (146).

ENG 94-202

can be obtained for the purpose. It would require the removal of about 39,500 cubic yards, the estimated cost of which, at 35 cents per cubic yard, is $13,825. Storehouse at Great Falls.-There is no place for storage of the public property at Great Falls, or for cement and other materials required when any work of construction or repairs is going on on that division of the aqueduct. A storehouse is urgently needed, and I propose to erect one about 40 by 20 feet in size, at a cost of about $1,500. The Chesapeake and Ohio Canal is now in operation, and the stone for the walls can be cheaply obtained from the Government quarry at Seneca, a short distance above the falls.

Inserting air valves and blow-off valves in the 30-inch and 36-inch mains.—In respect of this estimate I beg leave to quote from my annual report of 1890, as follows:

"It is important that more efficient facilities be provided for emptying and filling the old mains in case of accident, and of making connection fro.a main to main. "In either case a section of the main must be cut out and a new piece inserted, but before this can be done the main valve, at whatever distance on either side, must be shut, and the section of the main between these two valves, generally more than a mile long, must be emptied of its water. The time required for emptying depends not only on the sizes of the blow-offs in the valleys crossed by the mains, but also on the sizes of the air valves provided at the summits, for the water can not, of course, in any case be gotten out of a main any faster than the air required to take its place can be gotten in.

"In making the connections at New Jersey avenue and L street between the 36-inch main and the 24-inch by-pass, on the night of the 14th of April last, more than five hours were consumed in freeing the main of water, owing to insufficient blow-offs and air valves in the 36-inch main, and the refilling of the main after the connection had been made was so much prolonged by the want of proper valves for the egress of the air that it was nearly noon of the next day before the charging of the main was completed.

"Similar delays occurred at each of the numerous connections between the mains that were made after the 48-inch main was completed, and I was in each case obliged, in getting the air into the mains for emptying and out of them for filling them again with water, to have recourse not only to fire hydrants, but to the service-pipe spigots in private houses in the vicinities of these connections."

These delays are very expensive, night work costing about double the rates of day work, and the danger in case of fire in the district cut off from its supply of water is so great that large air valves and blow-off valves should be placed on both the 30 and 36 inch mains as soon as an appropriation can be obtained for the purpose. A patented device, of which I have obtained the details since the date of the report referred to, very much reduces the time required for inserting these valves, as well as their cost, and, what is very important, it enables the work to be done while the mains are under their ordinary pressure. The cost of inserting the required blow-off and air valves in the 36 and 30 inch mains will be about $6,250.

Removal of the accumulation of deposits in the conduit.-As stated in my last annual report, my inspection of the interior of the conduit from Great Falls to the distributing reservoir, in September, 1891, showed an accumulation of about 15,500 cubic yards of clayey deposits in the conduit throughout its entire length between these points of about 12 miles. These deposits, which diminish the capacity of the conduit, should be removed as soon as money can be obtained for the purpose. For the reason that the supply of water to the city must be interrupted while the work of removal is going on, a large part of it must be done at night. It will, therefore, be a tedious and expensive operation, and it can not be accomplished by means of the small annual appropriations for maintenance and repair. I include in my estimates an item of $14,000 for the removal of the deposits in the conduit, and this, if granted, would enable the entire conduit to be thoroughly cleaned out in one year. Rebuilding the bridge over the Spillway at the Dalecarlia receiring reservoir.—The Con · duit road bridge over the spillway at the Dalecarlia receiving reservoir and just beyond the District line is a wooden bridge on trestles that was built many years ago. The travel over the bridge is very heavy, it is decaying, and, in order to prevent accidents frequent repairs are necessary.

This bridge, which is of short span, should be replaced by a handsome.stone bridge of an architecture commensurate with Cabin John bridge and the other masonry bridge next higher up the line of the aqueduct (Griffith's Park bridge), and I include an estimate of $18,000 for it in my annual estimates.

Deepening the distributing reservoir.-The present bottom of the distributing reservoir being at reference 135 above the aqueduct datum, and the flow line of the reservoir being at reference 146 above this datum, the available depth of water is 11 feet. It has often been recommended in former annual reports that the depth be increased 13 feet, or to reference 122, the depth of the axes of the four 48-inch connections between the screen house and the gate chamber.

This would increase the storage capacity of the reservoir from about 170,000,000

gallons to about 290,000,000 gallons, and add to the coolness of the water and also to its purity, for, unlike the Dalecarlia receiving reservoir, which is nearly surrounded by woods, the distributing reservoir is fully exposed to waves, and the winds are sometimes so great as to disturb the bottom and make the water roily.

Should this be done, berms of 10 feet in width should be left at the foot of the present slope walls protecting the sides of the reservoir, the tops of these berms should be paved, and the deepened portions of the sides should be protected by slope walls of dry-rubble masonry 12 inches thick, laid on a broken-stone lining 6 inches thick. The cost of the work will be about $290,000.

I consider the work of deepening this reservoir to be of very great importance for the reasons given, and it should be done as soon as appropriations can be obtained for it, but as the improvement of the quality of the aqueduct water, the increase of storage capacity above the heads of our mains, the protection of the aqueduct, and other works herein mentioned are of more importance at this time, I have not included it in the estimates for the next fiscal year.

DESIRED PROVISION OF LAW IN RESPECT OF APPROPRIATIONS FOR THE AQUEDUCT.

I renew the following statement of reasons for this provision contained in my last annual report. In my judgment the desired provision or change in the law is of the utmost importance.

The annual appropriation for maintenance and repair of the aqueduct is now a fiscal year appropriation, and its availability terminates on the 30th of June of each year. Whenever the appropriation is delayed there is liable to be a time in the early part of every other fiscal year during which, should a break occur in a main either in the city or in the country this side of the distributing reservoir or in the conduit, or should any disaster occur at the reservoirs or at Great Falls, there is no money available for repairs.

If this appropriation should be made available until expended, some of the less urgent repairs toward the end of the year could be postponed until the next appropriation should become available, so that there would always be money in hand for repairing breaks in the mains or other works of emergency.

A leak in one of the city's old and decayed street mains or in one of the hundreds of small service pipes that cross the route of the 48-inch main, for instance, by undermining it, may cause it to break, and the quantity of water that would be discharged on the street, especially in the low levels of the route, would be so enormous that the property and even the lives of citizens in the vicinity of the break might be endangered.t

Even when, in the cases of delay in the passage of the regular appropriation bills, temporary provisions are made for the expenditures of the Government, considerable lengths of time after the beginning of the fiscal year elapse before official information (which only would warrant expenditures under these provisions of law) reaches disbursing officers.

On the 8th of July, 1892, in blowing off the 30-inch main at Foundry Branch, the heavy bronze sleeve through which the valve stem works was badly fractured, so that the valve could not be moved before a new sleeve could be cast and turned. The regular appropriation bill had not then been passed by Congress. I had only information from newspapers that temporary provision had been made for the expendditures of the Government and I had no money to my credit for the repair of the valve. Fortunately the valve happened to be shut at the instant when the accident occurred, else it would have wasted into the Potomac the water in the distributing reservoir at the rate of about 2,000,000 gallons per hour at a time when, on account of the low stage of water in the river, we had none whatever to spare.

*The late Gen. Meigs, in one of his frequent notes respecting the aqueduct, in which up to his death on the 2d of January, 1892, he continued to retain the deepest interest, called my attention to the care that would be required, whenever the distributing reservoir is deepened, not to cause leaks by uncovering and cutting into the uptilted and more or less dislocated gneiss formation that he found to underlie some portions of the reservoir.

The internal pressure on our mains at some portions of their routes is about 43 pounds to the square inch. This great pressure will be better appreciated if it be stated that it is nearly 40 tons to the running foot of 48-inch main.

All work on the aqueduct was suspended in July of 1892 until the 15th of the month, on which date the first official information reached me that temporary provision had been made by Congress on the 30th of June for the expenditures of the Government.