be longer used as an open sewer, and that in its present condition it is a great cause for creating and propagating diseases. In a report submitted several months ago by a board of engineers, detailed "to examine the model of an improved canal and ship-lock lock," and to consider "the value of the invention in facilitating commercial affairs of the country, and more especially its adaptation to aiding in the construction of a ship-canal through the city of Washington," the following remarks appear:

"The history, object, and condition of the Washington Canal have contributed a very considerable portion to the literature of the city for many years, and the various reports on the work in question, and projects for its improvement, would form a volume of matter of such magnitude as to render a revision of the whole subject too elaborate to be attempted here, especially as one does not appear to be necessary in this connection. The canal has been used since its construction for two purposes: the one for navigation, and the other as a main, open sewer; it has been the receptacle of the sewerage of the larger portion of the city, as well as of the surface drainage and the debris washed down through the bed of Tiber Creek. In consequence, it has been gradually filling up with a mass of most deleterious matter, and to such an extent as to render it not only entirely useless for the greater part of its length for the passage of boats, but to cause it to become a public nuisance. Attempts have been made during the last two or three years to partially abate the latter by removing a portion of the deposit by dredging, and by flooding the remainder by means of tide-gates; but after repeated efforts these means proved to be, as they were intended, only temporary expedients, and cannot be considered as having produced any very beneficial results.

"The various projects for the permanent improvement of the canal may be divided into three classes: the one proposes to continue the use of it, both for its legitimate purpose and as a sewer combined-in other words, to let it remain in its present status; the other, to employ it entirely for the transportation of boats, and to build a covered sewer parallel to it; while the third plan suggested is, to fill it up, excepting so much as may be necessary for a proper sewer, and discontinuing its use as a canal altogether.

"Mr. Bishop's (the patentee) project belongs to the first of these classes. In general terms he proposes to extend the canal up the river to Georgetown; to cut off the present sharp bends at different points; to place locks at its junction with the Potomac and the Eastern Branch; and to replace the present permanent bridges across it by turning or draw-bridges, in order to allow vessels of all descriptions to pass. In addition, as part of this plan, the Georgetown or Virginia channel of the Potomac is to be closed, and thus divert the tide of commerce from its present channel and direct it through the new one. He also contemplates to clear the canal and keep it free from objectionable matter by opening the gates and completely flooding it at certain stages of water in the river. Without entering into the details of this project it may be stated that the requirements of a navigable canal and a suitable sewer are incompatible, and that, in general, whatever tends to improve the one, necessarily injures the other. For example, a good sewer should have a declivity of at least one foot in one thousand, while the canal should be as nearly level as possible; the sewer should be no larger than is requisite to carry off all the semi-fluid mass or water that can find its way into it from its lateral branches or from surface drainage, while the larger the section of the canal, within reasonable limits,

the better; the sewer requires to be covered, while the canal remains open. The board cannot, therefore, recommend any project in which it is contemplated to use the same channel for the two purposes, however feasible the details of such an undertaking may be. It is a well known fact that along the wharves of all large cities there is a constant deposit from the contents of the sewers, which necessitates either almost continuous dredging, or the extension of the piers beyond its influence. There is no doubt that any canal, receiving the constantly accumulated matter from a great portion of the sewerage of a large city, must be filled sooner or later, unless there is a very strong and constant current through its entire length. In this case there is no possibility of producing such a current without extending the canal up to some point at or near the Chain or Little Falls Bridge, some three miles above Georgetown; even then the velocity of the water at the sides and bottom of a long narrow channel is so much retarded by friction, that, while there might be a sufficient strength to the current at the middle of the canal, a deposit would probably form on the sides and bottom. This would take place even in a constant current when the floating material is kept in motion and scarcely allowed to settle and become compact; how much more, then, would it obtain when locks were introduced, and the force of the water allowed to exert its influence only at intervals? That part of Mr. Bishop's project which contemplates the substitution of turning or draw bridges for the present permanent ones over the canal cannot reasonably be entertained. The canal now separates the main portion of the city from that section fronting on the Potomac, along which, at the present time, the larger number of wharves have been constructed for commercial purposes. To interfere or interrupt the constant travel and hauling of heavy freight on the streets leading from them would prove a very great injury to trade and the improvements now projected in their vicin ity. Even should benefit arise to one part of the city by enlarging the dimensions of the canal so as to enable sea-going vessels to enter, it would scarcely compensate for the expense of the undertaking, and the damage that would be sustained by another and a very rapidly improv ing portion. Should the money necessary to execute such a work be applied to dredging and opening the old Washington channel along the whole water front of the city, it would prove a more profitable and beneficial expenditure. A long and continuous line of wharves, extending from the arsenal point to the foot of the Little Falls, could then be built. The closing, as intimated in the method of improvement referred to, of an old and well established channel like the Georgetown or Virginia one, for the purpose of opening another and a more circuitous one through the heart of a large city, would scarcely meet with very favor able consideration in any point of view. The only practicable and intelligent plan of operations is to accomplish by mechanical means what nature originally designed should be the case, the reopening of the old channels as they existed before any encroachments were made upon them, or any obstructions allowed to be interposed to their detriment. In closing this part of the report, the board cannot look upon the facts just stated as being in any way discouraging to those interested in the improvement of the Washington Canal. If it cannot be made to serve two purposes, there is no reason why it should not be made useful in accomplishing one good result; one object well accomplished will cer tainly prove more profitable than two imperfectly executed. It is sus ceptible of a mathematical demonstration, that should either the second or third of the general plans referred to for the improvement of the Washington Canal be adopted—in other words, should the canal be

properly cleaned out, narrowed, straightened as much as possible, and a good sewer built parallel with it, the arch over the lower portion of Tiber Creek being also extended as high up as the boundary of the city limits, or should the canal be discontinued as such, and a portion of its width converted into a proper sewer, and in connection with this should the main channel of the Potomac be diverted towards and along the Washington shore, the value of the land reclaimed and the rise in the price of property effected by the change, would more than pay the cost of the whole undertaking, to say nothing of the vast improvement that would accrue to the city by benefiting its sanitary condition.

"Several additional bridges of iron should be constructed over the canal at different points. There should be one in the prolongation of Sixth street; another should be substituted for the temporary wooden one in front of the Agricultural Department; and the third to connect the grounds south of the President's House with those around the Washington Monument. They should be made highly ornamental, of the same width as the streets, and upon the same level."

PUBLIC BUILDINGS.

The several public buildings still remain under the immediate charge of the different architects, or of some of the officials attached to the various departments. The Capitol has been completed, unless it shall be determined at some future time to enlarge the central part of the building; the Treasury building has also been finished.

A board of officers has also prepared plans and estimates for a new War Department building, but no action has yet been taken towards erecting it. The commission authorized to select a site and propose plans for a new State Department have had the subject under consideration, and will report at the next session of Congress.

The White House, with the several buildings and the grounds attached to it, has been undergoing some very important and necessary renovations; many more demand attention as soon as the liberality of Congress will furnish the means. The appropriations for the present fiscal year, which are to be applied to the care and refurnishing of the building, are entirely inadequate for the purpose. It is a very old structure; upon a very minute and careful inspection of all its parts, it was found to be sadly out of repair, and even destitute to a great extent of many of the conveniences which are now considered absolutely necessary for the comfort and health of individuals. Immediately after the inauguration of General Grant as President, the improvements were commenced and pushed forward as rapidly as possible. Several of the rooms have been repapered and painted, and others have been replastered and painted in colors. The library has been paneled and its ceiling frescoed. The walls and wood-work of the upper hall have been repainted, and a substantial and ornamental stairway leading to it substituted for the old one. The spacious hall, into which the entrance from the north portico opens, has also been painted and its ceiling fres coed. The furnaces have been overhauled, and new ranges introduced into the kitchens. A handsome and convenient billiard-room has been attached to the house. The conservatory has been placed in excellent order, and well filled with suitable plants; an additional section has been made to it during the summer to be used as a grapery, a large number of the choicest vines having been already introduced into it. Several beneficial changes have also been made in the garden. The stable has been enlarged and otherwise improved. The drainage and sewerage

through the grounds will need attention during the coming year. The entire exterior of the building should be repointed and painted. Many other much needed renovations could be suggested. The refurnishing of the mansion is being gradually effected. It is to be hoped that most liberal appropriations will be made by Congress to preserve and supply the building with all needful appendages, and render it in all its appointments a fit residence for the Chief Magistrate of the nation. Attention is again respectfully called to my report upon the selection of a site for a new presidential mansion.

WASHINGTON AQUEDUCT.

The earnest attention of the Chief of Engineers is again called to the condition of this great and important work. Its thorough completion is imperatively demanded, and the necessary appropriations should not longer be withheld. There is no public improvement throughout the District of Columbia which conduces so much toward the health and wants of the permanent residents of the capital, as well as the comfort of the many thousand transient visitors and government officials who seek it for pleasure or business, as the Washington aqueduct. It is the only safeguard against the destruction of not only private possessions, but also of the immense amount of public property accumulated within the limits of a few square miles. There is a wealth of important archives stored away within its boundaries that can never be replaced should they once be destroyed. In a sanitary point of view, as well as in an ornamental and mechanical consideration of the subject, the means for supplying a material so much enjoyed and so much needed should be furnished without hesitation and without stint. The annual report of the engineer of the Washington aqueduct is herewith appended. It furnishes in great detail a statement of the many repairs which have received attention during the year, and of the renovation of a few portions of the work which have hitherto been left in an unfinished or damaged state. He also dwells upon the pressing necessity of finishing other very important sections. Many very valuable suggestions are offered, and much useful information furnished. Reference is respectfully made to his report for a condensed account of the present condition of the aqueduct, and also of a summary of the total cost up to the present time, with an estimate of the necessary amount to be applied toward its completion. As so many complaints are made by many citizens as to the scarcity of water, and as such an utter wastefulness is indulged in by others, the adoption of some system, by which a more equal distri bution can be arranged to the greater advantage of all seems to be imperative. Meters should be introduced into every house, as that plan appears to work well wherever applied.

It is again earnestly recommended to replace the old fire plugs on Pennsylvania avenue by new ones, and that they be connected directly with the government main along it.

The payment of the rents, and the purchase of the several small tracts of land which have been taken from private individuals for the use of the government, and which must be retained for the purposes of the aqueduct, is most earnestly urged. Several of them belong to widows, who are by no means in affluent circumstances. In some instances they have been compelled by the corporate authorities to pay the necessary taxes for the improvement of their property by the opening and repav ing of streets, when, at the same time, they have been entirely dispos sessed of its use for several years back. But a few thousand dollars

are needed to satisfy all such claims. As stated in my last report, "the great importance of introducing into the capital an unlimited supply of pure and wholesome water cannot be overestimated. The water thus furnished has become a great motive power at the different government workshops and buildings throughout the city; and when the capital of still the nation becomes what every enlightened citizen desires to see it, a larger demand will be made for both useful and ornamental purposes."

Including the estimates submitted for completing the Washington Aqueduct, the total cost of the work will not exceed four millions of dollars.

The estimates of amounts required to be appropriated for the publie buildings, grounds, and works, under my charge, for the fiscal year ending the 30th of June, 1871, are herewith appended.

I am, general, very respectfully, your obedient servant,
N. MICHLER,

Major of Engineers, Bvt. Brig. Gen. U. S. A.

Brevet Major General A. A. HUMPHREYS,

Chief of Engineers, Washington, D. C.

OFFICE OF THE WASHINGTON AQUEDUCT,

Washington, D. C., October 1, 1869. GENERAL: I have the honor to submit the following report of operations upon the Washington Aqueduct during the year ending September 30, 1869:

At the date of the last annual report, work had been suspended upon the construction of all the unfinished portions of the aqueduct, and the expenditures confined to such repairs as were absolutely necessary for the safety and preservation of the works.

In November an examination was made of the embankments of the distributing reservoir; it was apparent that they were very much worn by the action of the waves on their unprotected slopes, and it was deemed necessary for the safety of the reservoir to empty out the water. The twelve-inch main, leading from the pipe vault to Foundry Branch, was used for a drain, and the reservoir gradually emptied. It had been in use in its unfinished condition, for storage and settling purposes, over four years, and during that time the water supplied to Georgetown and Washington was generally clear and pure. Since then, being brought directly from the Potomac, it has often been muddy and impure.

The construction of this reservoir was suspended in June, 1864; owing to the failure of Congress to make any appropriation for its completion, no work has been done on it since. In form it is nearly a rectangle, 2,250 feet long and about 850 feet wide, with an area at the flow line of 44 acres. The level of its bottom is two feet above the bottom of the conduit at the influent gate-house, and fifteen feet above the center of the iron mains that lead from it at the effluent gate-house. With the water nine feet deep in the conduit, it is only seven feet deep in the reservoir, making its capacity at that depth equal to 94,500,000 gallons.

The work remaining to be done consists in excavating the bottom to an additional depth of thirteen feet; raising the dividing bank to the full height of the exterior banks; building a central gate-house in the dividing bank; building facings of rubble masonry on the interior slopes; completing the influent and effluent gate-houses, and the effluent screen well and pipe vault.