passing through and most of the latter in passing over the ground. Every part of the crust of the earth is a great filter which removes all of the suspended matter and also removes or transforms most of the organic matter of the water as it passes over the earth's surface, provided the distance traveled is great enough. Underground supplies therefore, unless taken at a depth near the surface or from localities which are subject to special pollution, are generally more free from organic impurities and bacteria of all sorts than are surface supplies, while the latter usually contain smaller quantities of mineral salts. Deep wells in some localities yield water so heavily charged with mineral matter or with gases as to render it unfit for domestic use. Even the water from comparatively shallow wells may be quite hard, due to the excess of mineral matter. Water collected from cultivated fields is apt to contain much organic matter and clay, silt, or sand in addition. Water from forests, meadows, or swamps usually contains much vegetable organic matter.

The most important and the most dangerous source of pollution is sewage. This affects surface supplies far more extensively than underground supplies. Public and private wells are often contaminated by near-by privies or cesspools. Mr. M. N. Baker, an able engineer, writing on the subject has well said:

In matters of water supply, above all things else, even the appearance of evil should be shunned; so the first principle of securing potable water is to avoid all supplies known or liable to be polluted and to choose those above suspicion. Where polluted water can not be avoided every effort should be made to stop the pollution, and if this is not sufficient, then the water must be purified.

In case a waterworks plant is being established, or a new source of supply added, the first object should be to select water of the highest standard of purity. The qualities to be sought are so important that they may be mentioned again: Freedom from disease germs, substances that derange the human system, color, odor, taste, and sediment. The first is of the most importance by far.

The ideal plan would be never to choose a water supply into which sewage, however small the quantity, is discharged, and never to allow such discharges into any existing source. It is difficult to carry out this ideal in any case and the magnitude of the task increases with the size of the supply. We are, therefore, sometimes forced to consider whether some small or remote source of sewage pollution may not be tolerated in order to render an otherwise satisfactory supply available, especially if all others worthy of consideration are much more costly. If the pollution be small, some means of preventing it may often be found; if it is both remote and small the danger is correspondingly lessened. But where shall the limit be placed? Both individuals and communities are loath to incur trouble or expense beyond a certain point in order to avoid remote chances of danger or death. Each case has to be, and should be, settled on its own merits. Regret it though we may, it sometimes becomes necessary to take some risks, lest the financial burden due to avoiding them be greater than can be borne. There is a limit by law, in some places, and by local public opinion everywhere, beyond which tax rates and bonded debts can not pass. It is less of a burden on one's conscience and far safer for all concerned to urge that no sewage pollution should

be tolerated than to name any small percentage of quantity in relation to the total amount of water or any distance at which the admission of sewage could be ignored.

Fortunately there is always some avenue of escape from death-dealing water. Either a natural supply may be found, pollution prevented by legal measures, purification adopted, or, as a last resort, a dual supply may be provided, pure water in very limited quantities being furnished for drinking and cooking.

The city of Manila has an ordinance regulation for the protection of its water supply. In times of cholera epidemics this law has been frequently invoked, and in some cases enforced by military authority. Laws for the protection of water supplies are of little value unless backed by the force of public sentiment. The questions involved are often more than local in character. They are sometimes interstate and international in their scope. The prevention of water pollution is a broader question than the preservation of the water supply. Waters not used as sources of supply must be protected from such pollutions as will give rise to offensive odors. It is evident that if all population were excluded from drainage areas there could be no sewage pollution. The attainment of this ideal condition is possible only when the municipality or private company owns or controls the entire drainage area. Birmingham, Liverpool, and Manchester and many other cities in England have bought up all the land in the drainage areas of their water supply. The question has not been given the attention it deserves in the United States and its possessions. Manila has just extended its intake beyond the limits of population and the entire new watershed is under the control of the Government, and arrangements have already been made to guard against its being inhabited. The present watershed is inhabited by more than 10,000 people, on which account the city water is always a source of danger to the health of Manila, which becomes a serious menace when cholera makes its appearance, frequently rendering it necessary to guard the watershed with United States troops to prevent its pollution. When the new system is completed the necessity for a patrol will no longer exist because the intake is beyond the limits of populated territory. The engineer in charge of this work reports that the new water supply will probably be ready for use within a year.

The conditions are more serious in the provinces, where the danger of drinking polluted water is not recognized. The Bureau of Health has endeavored to help matters by urging upon the people the advantage of boiling, distilling, and filtering the water. The masses will not use boiled or distilled water, but have no objection to water which has been filtered. As mechanical filters were entirely out of the question, this Bureau has devised a simple house filter consisting of an ordinary native banga (a jar made of clay), of the size desired, into which is placed two or three inches of gravel, and on top of this about a foot of clean river sand. The filter should be placed on a stand and under the

faucet and a tap inserted in an opening in the lower part of the banga to allow the water to flow out after it is filtered through the two strata of different densities. It is not claimed that this process removes all the danger from the water, but it greatly lessens the number of organisms. It is advisable to pass the water through another filter after it has passed through the preliminary filter. These filters are within the reach of all, costing only a few centavos. They are easily cleaned. Bangas to the Filipino people are what water coolers and water buckets are to the Americans. The accompanying sketch will show the simplicity of the above-described filter:

Fine clean sand

Gravel

It was formerly supposed that filtration was purely a mechanical process. It was believed that a mass of sand perfectly inert in itself would in no matter effect a chemical change in the contents of the water, but it is now known that water is purified while passing through a filter by the agency of nitrifying bacteria, in the same manner as when passing through nature's great filter, the earth. These nitrifying bacteria take the organic matter and transform it into nitrates. After a filter has been in use some time a thin layer of sticky matter forms over its surface and thin films of the same substance cover every minute particle of the filtering material, especially in the upper layers. It is these layers and films that retain the bacteria. Here the organisms in the water, pathogenic and nonpathogenic, are retained and here most of them perish only a few inches from the surface. Those that penetrate deeper are liable to be caught in the same manner and in addition they suffer through the lack of food, since the organic matter on which they depend for a living has been changed before it reaches them. Thus it will be seen that it is not necessary to change the filter's contents as often as

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might be supposed, yet it is also enjoined that filters should be kept clean. What was once considered a mere straining is now positively known to possess mechanical and antibacteriological properties as well. There are many disease germs which do not multiply outside of the human body and the problem is, after they have once passed out, to prevent their reëntrance into their natural habitat. This is the principal object of all methods of water purification.

It is quite a simple matter to plan the protection of the water supply of Manila, but when the problem is attacked in the provinces it is quite another story. In most municipalities, water-closets and privy vaults are practically unknown, the excreta being removed from the ground by pigs. If these pigs could be taught to do their duty, and nothing else but their duty, all would go well, but they wade into the rivers and into the streams, not so much to wash their dirty feet and noses as for the purpose of seeking other fields of filth to conquer. In the season of rains pollution is also carried into streams by the surface water which is discharged into them. To establish a system of waterworks in each municipality throughout the Philippine Islands is impracticable and could not be seriously considered, hence the Bureau of Health was confronted with the necessity of devising other means to protect the public. After due consideration it was decided that artesian wells would come nearer affording the desired protection than any other available agency known. Great undertakings always move slowly, and no one who is familiar with the subject, knowing the financial conditions of the country, would question for a single moment the fact that to supply the six hundred municipalities of the Philippine Islands with a sufficient number of artesian wells to accommodate the inhabitants is a stupendous undertaking, yet a start has already been made. Wells are in operation in the Provinces of Pampanga, Bulacan, Cavite, and Cebu. In the Province of Pampanga very satisfactory wells have been obtained at depths that vary from 100 to 135 feet, and which flow at the rate of 20 to 50 liters per minute. Other wells in the same province, with the surface at about the same sea level but bored to a depth of from 180 to 200 feet, have a flow of from 75 to 114 liters per minute, and this amount is not much lessened in the dry season, while the amount from the more shallow wells is greatly reduced during this time.

The mortality in some of the towns which use artesian water exclusively has already dropped 20 per thousand over corresponding periods last year.

The Commission in some recent legislation (Act No. 1662) has made it possible for many more municipalities to avail themselves of loans from the Insular Government for the purpose of installing artesian wells, so that in the near future still further reduction in the mortality can reasonably be expected.

LEGISLATION.

During the year several laws have been enacted for the regulation of questions which concern the health of the people and the interests of the Bureau of Health. One of the most important local measures from a sanitary standpoint is Act No. 1526, entitled "An Act for the prevention and suppression of Asiatic cholera," passed August 17, 1906. This act was passed to do away with the dangerous practice, confined almost entirely to Chinese market gardeners, of sprinkling growing garden produce with a mixture of urine, feces, and water which serves the double purpose of fertilizing and irrigating the soil, and satisfies, at the same time, the Celestial's idea of economy. This filthy method, so common in Chinese farming, is a dangerous procedure in the Philippines, and has been the means of disseminating cholera and dysentery. It is now expressly forbidden for any farmer, market gardener, or other person to use any human excreta, excrement, dejecta, or the contents of any water or earth closet, privy, vault, cesspool, latrine, pail, or other receptacle for human feces or urine as a fertilizer on any land on which is grown any article or product intended for food or human consumption, or to allow any human excrement, excreta, or dejecta to be sprinkled on or applied in any manner, or for any purpose, to any crop, product, or vegetation grown on said land.

Another law which is of considerable importance to small municipalities is Act No. 1530, amending the Municipal Code, by giving to municipalities the right to charge a fee of not more than 50 centavos for burial permits and permits for the removal of the bodies of deceased persons. The money derived from this source is covered into municipal treasuries and becomes available for local expenses, the item of sanitation receiving its share.

Act No. 1580, entitled "An act making appropriation for certain public works, permanent improvements, and other purposes of the Insular Government,” while not remedial legislation, was of so much importance in the administrative operations of the Bureau of Health that it merits special mention. This act carried several sanitary appropriations; 10,000 for the extension of the water system at the Culion leper colony; 20,000 for the construction of a sewer system in Bilibid Prison; 20,000 for sanitary beds for the inmates of the said prison, and 55,000 for the construction of buildings and their permanent equipment, in the San Lazaro Hospital grounds in Manila, for the care of 250 additional insane persons.

Another law directly affecting the work of this Bureau is Act No. 1613, entitled "An act amending Act No. 308 and providing for the establishment of municipal boards of health and fixing their powers and duties." This act provides that with the approval of the respective municipal councils and the approval of the Director of Health, district