The larger proportion of contamination of Potomac River occurs at and above Cumberland, Md. The tributary streams below this point do not add much to the contamination.

Mr. Newell, of the Geological Survey, states in his report that if we could dam off the stream below Cumberland, the greater part of the pollution would be removed. Now, if the river would purify itself by aeration and sedimentation, it would be natural to suppose that the pollution would become less and less as we approach Washington. On the contrary, Dr. Sprague reports that the samples of water taken at various places in the Potomac Basin do not show a diminution of the colon group, but a relative increase as we approach Washington. This fact alone would appear to be sufficient to demonstrate the fallacy of self-purification of a stream. There is evidently more than a coincidence between the presence of the colon group of bacteria and the number of cases of typhoid fever. Chart A has been prepared to show this relation.

By reference to this chart it will be seen that the upper line represents the total death rate, by months, from typhoid and typhomalarial fevers for the eleven years ending March 1, 1898. The second line represents the number of deaths from typhoid fever during this period, and the lower line the number of deaths from typhoid fever in the year 1897-98, ending March 1. There is no doubt that the deaths reported as typhomalarial are nothing more or less than typhoid, as the increase of deaths from this disease is synchronous with those of typhoid. By comparing these mortality curves with those prepared by Dr. Sprague in chart No. 1, it will be seen that there is a coincidence between these and the curve of the intestinal bacteria. The same relation between this group of bacteria and the prevalence of typhoid fever has been shown in cities other than Washington, as, for instance, Hamburg. Typhoid fever was endemic, prevailing in epidemic form in the summer and fall months. The bacteriological analysis of the drinking water demonstrated that the increased number of intestinal bacteria always coincided with the increased prevalence of typhoid fever and diarrheal diseases. This condition prevailed year after year until the water was filtered. Since then there have been no such coincidences.

We have still more evidences of the pollution of the Potomac River. Dr. Kober reports that in 1890 an epidemic of typhoid fever occurred in Cumberland, Md., and three weeks later there was an increase in the number of cases in Washington. If we allow from three to five days for a given volume of water to travel from Cumberland, Md., to Washington, and from fourteen to eighteen days for the period of incubation from typhoid fever, it would coincide with the increase in the number of cases.

The principal causes of pollution from sewage are derived from the towns and villages located in the Potomac Basin. There are about 35 of these located on the Potomac and its tributaries, which have in the aggregate a population of about 75,000, and are distributed as follows:

Typhoid fever has been reported to prevail in Cumberland, Staunton, Harpers Ferry, Elk Garden, Westernport, Frederick, and Hagerstown.

The conclusion to be drawn from the above statements is that the Potomac is polluted with sewage to such an extent that it is a constant menace to the health of the inhabitants of the District of Columbia. This is not a new statement, but is made only to emphasize what is already well known.

REMEDY.

Several ways may be considered for purifying the water:

First. The control of the watershed.

Second. Seeking a new supply.

Third. Improvement of the present supply.

According to the report of the hydrographer of the Geological Survey, the drainage basin of the Potomac River has an area of over 11,000 square miles, which lies in four States-Pennsylvania, Maryland, West Virginia, and Virginia. It would be next to impossible to control this vast area or abate the nuisances thereon without practically depopulating it. It need not be considered further.

A new supply must either be taken from a watershed capable of yielding an adequate quantity of water, or obtain it from artesian wells. There is no watershed near Washington which would furnish the water supply which is not open to the same objections as apply to the Potomac Basin. Even if it were possible to procure a new supply, the expense of purchase and that incident to policing would be far in excess of the expense connected with any proposition heretofore advanced for the purification of the present water supply. Artesian wells would not, owing to the geological formation of the District, be practicable.

Filtration.-Filtration of water is accomplished in one of two ways, the rapid method of mechanical processes, or by the slow method of sand filtration.

The mechanical method, while it removes the suspended matter from a water, performs the function of removing bacteria in a variable manner, depending on the character of the appliance, the method of operating, and the water to be filtered. The removal of the bacteria is what should be defined as filtration, and a filter which removes the bacteria successfully will remove the suspended matter: but filters may remove the suspended matters and fail to reduce the number of bacteria. This is usually what the mechanical filters do. Mechanical filtration would not be successful in removing the bacteria from the Potomac water on account of the large quantity of suspended matter.

Household filtration has its advocates. The filtering apparatus best adapted for household purposes are those made of unglazed porcelain or infusorial earth, such as the Pasteur-Chamberland or the Berkfeld. These filters, if perfect (and very few of them are), will efficiently filter water for a short time only. They require a great deal of care and attention, and must be cleansed at frequent intervals, for if not, they become a greater menace than the raw water. They are also quite expensive and out of reach of the masses, those who require them most. You may enjoin and plead for people to boil their drinking water, but they will not do it unless threatened with a visitation of cholera, and then only at starts and intervals, it being proportional to the degree of their fright. My opinion is that if you desire people to use boiled water you must boil it for them.

Sand filtration is the most practical solution; in fact, it seems to be the only way in which a large quantity of water can be purified and rendered potable.

It was on account of the high death rate from typhoid fever that this system of water filtration was adopted and perfected by the European cities. Since its use the death rate from typhoid and other diseases has fallen to a very low rate. In view of the good results accomplished by their use of it, it is remarkable that no more than four of our American cities have adopted this system, and particularly Washington.

It is hardly within the province of this report to deal with the construction and method of operating sand filter beds, as this is for engineers to consider.

The description of these filter beds has been promulgated now for several years, and is common property. Anyone can inform himself of the details of construction and operation if he care to manifest a sufficient interest. A proposition has been advocated to send a commission to Europe to study this system of water purification, and to report on its adaptability for the water supply of Washington. While such a commission may by personal inspection gather facts concerning the best method of constructing and operating European filters, little that is new will be added to our present knowledge.

Three cities of the United States have already followed the example of Lawrence, Mass., and have filter beds in successful operation. All these cities are within twelve hours' travel of Washington.

I can not agree that the situation is not serious, or that it can admit of further delay by reason of the fact that the death rate from water-borne diseases has shown no material increase within the past three or four years. The best that can be said is, it is bad; we have a remedy, and the sooner it is applied the more lives will be saved-lives which are being sacrificed by delays or negligence which should be characterized by no less a term than criminal.

During the past eleven years ending March 1, 1898, there have been 2,150 deaths reported from typhoid and typhomalarial fevers, not including those from diarrheal diseases, of which at least one-half are direct'y due to polluted water. If during this time a purer water supply could have been furnished, it is believed that the death rate from typhoid fever alone would have been diminished 80 per cent, a saving of 1,720 lives, and the prevention of over 16,000 cases, not to mention the expense incidental to sickness.

It is considered a crime to buy and sell human beings, yet there are worse crimes being enacted here in Washington. There are persons who have deliberately prevented the establishment of hospitals for the care and treatment of the poor little unfortunates, and have made it impossible so far by creating a sentiment against providing a filter plant unless the sewer system be extended and improved.

No one will attempt to deny the necessity of an adequate sewer system, but more good will come from purifying the water supply than from the renewal of the present sewers or their extensions, especially to outlying farm lands.

Munich, celebrated for its former high death rate from water-borne diseases, had no house sewer system until two years ago. Neither had Paris (now constructing). Notwithstanding this, the death rate was far below the cities which use raw river water. In Baltimore, Md., which still clings to her cesspools and surface drains, the water is reasonably pure, and the death rate is far below Washington.

The construction of a filter plant for Washington appears to be easier than for most cities. The Government already owns the land, and has already constructed the reservoirs and basins, one of which could be readily changed and converted into filter beds.

The Delecarlia or the distributing reservoir could be converted into a filter, perhaps the latter, and the water could be allowed to sediment in the Delecarlia before it is filtered. This might be an advantage at times when the water is very muddy.

It is further suggested that a small filter bed-say 100 feet square-be erected in a corner of the reservoir for experimental purposes, in order to determine synchronously with the construction of the filter beds the best material for filtration, as well as the rate of flow, etc. In this way the question could be settled without delay. When the filter beds are ready to receive the filtering material sufficient data would be gathered to determine the best plan of construction and operation. A part of the receiving reservoir could be used, as now, for storing a supply.

It would seem to be an easy matter to enlarge the filter beds from time to time by utilizing the land just to the north and south of the receiving reservoirs, and in this way be able to furnish all the water required.

Respectfully submitted.

J. J. KINYOUN,

Passed Assistant Surgeon, Marine-Hospital Service, Director. SURGEON-GENERAL MARINE-HOSPITAL SERVICE.

The inquiry was continued until August 1, 1898, to complete the year, and the additional data collected only went to confirm the conclusions already drawn.

This investigation was intended to be preliminary to the general subject of the pollution of public water supplies, where the interest of one or more States are involved, which it is hoped the Service will be able to undertake at as early a date as possible.

LABORATORY INSTRUCTION TO OFFICERS OF THE SERVICE.

The usual course of instruction in clinical microscopy and sanitary chemistry was begun on January 4 and continued until May 1. Two officers of the Service availed themselves of this course. The time of the year when it is practicable to give this course precludes the study of the malarial organism except by prepared specimens. This is quite unsatisfactory. Some arrangement should be perfected by which this instruction could be given, as it is highly important that this subject should be well understood by the officers of the Service.

The revised regulations permit the officers of the Service to receive laboratory instruction from time to time as their services can be spared. Some further provision should be made by which the laboratory should be open to officers and others for special research work. The laboratory is now so well equipped in instruments and apparatus that exceptional facilities can be offered for this work.

CAR SANITATION.

The subject of car sanitation is still under investigation. It has been now nearly two years since it was begun. It has proven a far more difficult task than was first supposed, so many obstacles have from time to time arisen which have caused repeated delays in obtaining satisfactory data regarding the sanitary conditions existing in the railway coach. So far the results of the investigation are more satisfactory than was at first thought possible. They all point to there being not so much danger to the public health from the railway coach as was at first supposed. It is expected to finish this work within two or three months.

The experiments undertaken at the same time to demonstrate the best methods of disinfecting railway coaches have been brought to a successful termination, and as a result of this, cars are now being