the lining; but, as before shown in this report, we are required to bstitute rubble masonry, at an increased cost of $2.25 per yard—an inease of 90 per cent. It was also assumed that the money required to rry on the work would be supplied in time to prevent any suspension operations, but such was not the case.

After work was resumed it soon became evident that the extent of nnel calling for lining had been underestimated, and, in fact, nearly the rock penetrated since that time is such as to make lining unquesnably necessary; besides, a considerable quantity of rock that was nsidered firm and compact when the estimate of 1885 was made has ice then developed imperfections and elements of weakness such as seriously threaten the stability of the tunnel if left unprotected by ing. Thus we now find it important to submit an estimate involving e lining of a much greater length of tunnel than was before contemated, and at a higher price to the extent of the difference in cost beveen rubble masonry and dry-stone packing.

1

The original estimate made provision for lining 10,893 feet of the tunel, while in that now submitted this length is increased to 15,325 feet; it the original estimate proposed lining the entire cross-section of the innel, with invert, side wall, and arch wherever any lining at all was laced, whereas the method now proposed is to vary the lining accordg to the character of the rock, with a view to reducing the cost of uing to minimum. Thus of the 15,325 feet which it is now proposed to ne, it is estimated that 8,025 feet should have the full lining, 2,900 feet here the lining will consist of arch and side walls, and 4,400 feet of rch only.

The total estimated cost of the tunnel now submitted is $1,181,582.55. 'he amount already appropriated is $999,534.55; whence, on a close stimate, it appears that an additional appropriation of $182,048 is reuired to complete the work. But I would urge that the amount of the ppropriation be made $200,000, in order that we may be prepared for nseen emergencies, and thereby avoid any further delay in completing he work. The details of the new estimate will be found in the report f Lieutenant Townsend, which is transmitted herewith.

The completion of the tunnel as now proposed involves the least mount of lining compatible with the security of the work; it is a serius question, however, whether we should not go further and arch all he rest of the tunnel in order to provide against any possible danger f its becoming blocked by a fall of rock from the roof, such as might come n time through the development of faults or elements of weakness that re not now perceptible. To do this will cost about $120,000, in addition o the estimate submitted above. I am of the opinion that, in consideraion of the great importance of doing everything possible to insure he stability of the work, it would be a wise economy to increase the ppropriation to $320,000 for this additional element of security.

When the water supply is finally passed into the tunnel, and the cities have become dependent upon it, any accident that might call for à recurrence to the present inadequate system of supply would cause serious trouble, if not absolute distress in certain sections. For this reason I am inclined to the opinion that it may be well to let the tunnel fill with water when the money now available is exhausted, and pump It out after the new appropriation becomes available, thereby making actual test of the stability of the work before the community becomes dependent upon it for its water supply. At the same time I can not arge too strongly an appropriation, at the earliest possible date, of the full amount now estimated as necessary for completing and realizing

the advantages of this great work, which affects so closely the e and health of nearly 200,000 people in this District.

NEW RESERVOIR.

r

The progress made by the contractors on the reservoir during past fiscal year has been slow and entirely unsatisfactory, the wes force having been entirely too small as a rule, and the plant insu and in poor condition.

At the beginning of the year 727,000 cubic yards of earth had be cavated; the mean elevation of the dam was 153.7 or 6.3 feet below g the intercepting masonry conduits had been built for an agg length of 3,679 feet; the slope paving of the dam had been comp also the paving of the east slope of the reservoir, and 255 feet in iof the west slope. During the year 101,186 cubic yards were excav and the dam thereby practically completed; the intercepting coz have been completed; the slope paving on the west and north wa tended over a length of 1,994 feet, and 942 feet of road gutters graded and paved. For the purpose of paving, 6,810 cubic yar stone had to be hauled from the tunnel dumps at Champlain ave Rock Creek, and Foundry Branch, that taken from the tunnel a Howard University shaft having been soft and unfit for use.

The original appropriation ($431,273.75) for this work was exha in the early part of the fiscal year, but the general deficiency a proved August 4, 1886, appropriated the additional sum of $160,0 complete the reservoir, making the same conditions in relation t expenditure as applied to completing the tunnel, all of which are set forth in that part of this report relating to that work. The E of Engineers therein referred to was required to determine whether "changes are required in the method of lining and perfecting the ervoir," and reported thereon as follows:

"The inspection of the new reservoir satisfied the Board thai work is proceeding in an entirely satisfactory manner, as propost the special Board of 1885, and this Board has no changes to re mend."

The act of appropriation provided that the work should be conti "under the contract heretofore made or by a reletting, as in the dis tion of the Secretary of War shall be most promotive of the interes the Government." Careful consideration having been given to matter, it was finally determined to continue the work under the o nal contract (see correspondence in relation thereto accompanying report), and to this end that contract was extended to December 1886, and again to Jane 30, 1887, which was the date fixed for com ing the work. This the contractors failed to do, however, and the tract has been finally extended to October 31, 1887, at which time: believed the contractors will have completed what is required of th comprising as its principal features about 25,000 cubic yards of e vation, 9,500 square yards paving, 20,000 square yards sodding, bes trimming and cleaning the slopes and bottom of the reservoir to tr true planes and grades.

After this is done the construction of the gate-house, with its tributing conduits on the bed of the reservoir and its connection w the effluent 75-inch main, will put the reservoir in condition to rece the water supply. This can all be accomplished with the present propriation during the current fiscal year, and before the completion the tunnel by which the water supply is to be brought to the reserve At this writing it does not appear that any additional appropriat

t

be required for completing the essential features of the work, but it kely that additional money will be needed to properly finish up the unds about the reservoir. No appropriation for this purpose is asked at this time, but it may be made the subject of a special communion at a later date.

he total estimate for work done by the contractors up to June 30, 7, is as follows:

Of the above total $51,696.54 is for work done during the past fiscal ar. In addition there has been expended for stone, trap rock, and ck furnished to contractors $41,024.59, and for surveys, engineering, tingencies, etc., since the beginning, the sum of $54,547.51, making e total expenditures, including retained percentages and outstanding bilities to June 30, 1887, $474,306.09. The appropriations have been follows:

of July 15, 1882.

s of August 4, 1886.

Total

lucting therefrom the total of expenditures and liabilities, the balance vailable for continuing and completing the work at the close of the scal year was.

$431,273.75 160,000.00

591, 273.75

116, 967. 66

LAND FOR AQUEDUCT EXTENSION AND RESERVOIR. The only payment made on account of land during the year was that June 6, to Robert Proctor, for $62, and recording deed of the same, 50-total $63.50, on account of land to extend aqueduct. All preus payments are given in the annual reports of the Chief of Engin-s for 1885 (pages 2476 and 2477) and 1886 (pages 2059 and 2060). The balance available for land at the close of the fiscal year was as Hows:

- "land to extend aqueduct " "land for reservoir"

$25,007.99 814.28

MAIN CONNECTIONS.

The only work done on the main connections during the year was the king of the 75-inch outlet main from the new reservoir, which was ne between January 19 and February 28, 1887.

The total amount expended on account of main connections te 30, 1887, was as follows:

For water-pipe, valves, and special castings.
For pay-rolls for labor, superintendence, etc
For materials, tools, supplies, etc.....
For hauling pipe from depots, etc

Total.......

8122

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of which the sum of $838.90 was applied during the past fiscal The original appropriation was $165,400, and the balance now at ble is $2,008.58, which will probably suffice to complete this partwork by making proper connection with the gate-house when bui The following is an abstract of contracts for increasing the water ply of Washington, D. C., in force during the fiscal year ending 30, 1887:

For dam.-Chittenden Brothers, of Washington, D. C., contrac date of contract, November 7, 1883; date of supplemental cont March 4, 1884. These contracts were completed August 21, 1886.

For tunnel-Beckwith & Quackenbush, of Mohawk, N. Y., con ors; date of contract, October 29, 1883; date of supplemental con October 18, 1886. These contracts expired June 30, 1887, but have extended to November 30, 1887.

For reservoir.-Maloney & Gleason, of Washington, D. C., contr ors; date of contract, October 30, 1883; expired June 30, 1887; tended to October 31, 1887, subject to monthly forfeit of $300 per п during period of extension.

The following is a money statement for the fiscal year ending J 30, 1887:

SIR: We desire an extension of the time named in our contract for the complet of the Washington Aqueduct tunnel to June 30, 1887, and we offer as reasons whys an extension should be made the following:

(1) Increased depth of shafts.

(2) Difficult and bad ground not anticipated.

(3) Delay to work caused by necessity of lining tunnel close to headings. (4) Stoppage of work by order of Capt. T. W. Symons, dated January 28, 1 since which time work has practically been suspended, except pumping to keep t nel free from water.