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the dam, on account of earthquakes, it can be provided for simply and easily by small dams farther back in the mountains whenever experience shows it to be desirable to increase the storage. It is not probable, however, that it will be found necessary for many years.

QUALITY OF THE WATER.

The quality of the water to be delivered at Manila is, I believe, of paramount importance. It seems hardly necessary in this generation to use any arguments to give weight to the urgent responsibility resting upon everyone connected with the solution of the question to give to it the most careful and sober consideration. It should never for a moment be lost sight of that the water may be made to convey to every consumer either influences for life and health or for disease and death. From the low standard of the commercial aspect alone the furnishing of a water supply which is above suspicion is the very best investment that a city can make. It invites trade and commerce and does its share toward the permanent prosperity of the city. In connection with good sewers to remove filth from the city it does more to reduce dangers and expenses incident to epidemics than almost any other agency over which man exerts control. Manila is now served with raw water from the Mariquina River, which is the best conveyer that man could design to carry the germs of disease to everyone who is unfortunate enough to be obliged to drink it. So well is this understood by the physicians and biologists in the city that the most watchful guard is kept constantly against the dangers that lurk in the water supply, and boiling, distillation, and bottled waters are resorted to. It has been shown by Doctor Musgrave that the dreaded amoeba, the most persistent and dangerous of all the disease germs of the tropics, may be found in every sample of water drawn from the taps in the city. While it may be difficult to prove that the germs of cholera or other tropical diseases are conveyed to Manila in the water, in times of epidemics, there is a well-grounded suspicion from the environmental conditions just above the point of intake at Santolan that such may be the fact.

I come now to the more technical consideration of the investigation into the present condition of the water and the probable freedom from contamination of the future supply if the plans proposed are carried out.

Dr. Paul C. Freer, superintendent of the Government laboratories, has furnished Major Case with the results of the chemical and biological examinations which have been made under his able direction. These are published as an appendix to this report.

As far as the chemical results are concerned the Mariquina water is of excellent quality. An examination of the amount of nitrogen in its several conditions shows that the amount of organic matter present is not above the normal of good water supplies. There is an absence of nitrites and the chlorine is low. The bacteria are not abnormally high for river water, and the water is comparatively soft, so that it will not require a large amount of soap in the laundry. The water is free from color, showing an absence of swamps upon the watershed.

The reports in regard to the sanitary conditions between Montalbon and Santolan explain themselves so fully as to require no comment, but the finding of amœbæ in the natural waters of the river above the gorge has added weight to my conviction that in any event the water drawn from the storage reservoir should be filtered before being distributed to the consumer. Wherever water is impounded in a reservoir it is subject to many growths which impair its quality for a domestic supply. Even where reservoirs are constructed in the most ideal way, by removal of all organic matter from the site of the reservoir and the deepening or filling of all the shallow margins, called technically "shallow flowage improvement," there are times when large growths of algae and other organisms infest the water in a reservoir of ordinary size and render it disagreeable.

The Mariquina River, in times of heavy rainfall, will bring considerable amounts of sediment and more or less matter of an organic or nitrogenous nature into the reservoir, which, in connection with the high temperature of the water, will render it at times unfit to use. For these reasons I am clearly of the opinion that the water should be filtered at some convenient spot on its way to the city. Favorable sites occur at the correct elevation. The water can then, after purification, pass to the distributing reservoir, which should be covered to protect the filtered water from the air and sun.

The necessity for filtration becomes still more imperative when we consider the presence of ambæ in the water in its natural condition. The problem as to whether this protozoa can be removed by filtration is, so far as I am aware, a new one. We know that in well-regulated and properly conducted systems of filtration a very high percentage of the bacteria are removed and the use of infected waters rendered com

paratively safe. The experience of the world for many years has taught this valuable lesson. We know, too, that amoeba live upon the bacteria and are much larger in size, but text-books are silent upon the subject of filtration in connection with amobæ. The inference would naturally be that if filtration will remove the typhoid and cholera bacilli it will also remove the amabæ, but this does not follow. To throw some practical light upon this important question Major Case has at my request undertaken a series of experiments for the purpose of ascertaining whether ambæ can be removed by filtration through open sand filters after the English pattern. There are some reasons for supposing that amoeba will pass through any sand filter, however fine the particles or however thick the layer. The experiments are still in progress. The chemical and biological work is carried on under the direction of the laboratories.

PHYSICAL ASPECTS OF THE PROPOSED WORKS.

Dam.-I approve of Major Case's plan for the building of the dam in the gorge above Montalbon. The dam, in plan, is to be curved and the section a gravity one. Although it would be highly desirable to raise the proposed dam to a greater height than 60 feet-and in any other country than one in which earthquakes are of frequent occurrence I should recommend this to be done, both for the purpose of securing more head and more storage-I consider that a judicious mean has been selected. More storage can at any time be secured by building low dams farther back in the mountains, and at small expense, and more head can be secured by enlarging the section or reducing the friction in the conduit line. In considering the security of the dam all that man can do will have been done if it is built so securely that none of the forces with which we are familiar will disturb its position. The dam should be so constructed that the largest freshets, and of any depth, will sweep over its entire crest and fall upon a mass of enormous bowlders at its base. I can imagine that an earthquake might crack such a structure, or even injure it severely, but it is difficult to conceive that the dam, built into the solid rock as proposed, and itself composed of masonry, could be so wrecked as to allow the impounded water to escape in one large mass. Should this occur the presence of the large lake, in connection with the Pasig River, would materially reduce the dangers of such a flood to the city of Manila. Steel-pipe line. The proper construction of the steel-pipe line is one of the most difficult problems connected with the new works. If it is well built it will have a comparatively long life, say fifty years, and if there is a single flaw in any of the many slow and tedious processes leading to its final acceptance that flaw will be sure to be the cause of annoyance and trouble. Steel-pipe lines are of comparatively modern invention and improvements are constantly made in their construction. It is claimed on the Pacific coast by some experts who have had much experience in the use of wrought iron instead of steel for mains that the wrought iron is very much the superior of steel for this purpose, and the largest pipe now under construction for San Francisco's supply is of this material. It is claimed that the life of a wroughtiron pipe is much greater than one of steel, and where certain conditions are fulfilled in the piling of the bars in the furnace, so as to produce an iron in laminated layers, I am inclined to believe from some investigations I have recently made on this subject that there is good ground for the claim. Wrought iron, properly manufactured, is, however, more expensive than steel.

There are several methods of constructing a steel pipe, but the most common are the two known as cylinder joints and butt joints. The latter are more expensive, but to my mind are more economical in the long run, everything considered. They are built with countersunk rivets like a ship's bottom, and offer the minimum resistance to the passage of the water. I have made a variety of computations to aid in the solution of the problem of the proper size and method of construction of the steel main for the city of Manila, but I thoroughly recommend before a contract is let for this important work that some one in the interests of the city be charged with the duty of visiting some of the steel-pipe industry in the United States, feeling sure that the city will be the gainer by the information secured.

It is possible that it may be found desirable to build a considerable portion of the proposed conduit line in tunnel, under pressure, should the dhobie rock be found of proper character and to lie in a favorable position. Such a tunnel would be naturally of larger sections than a steel pipe and would save head, besides being permanent in character. Surveys and borings are now in progress to determine this question.

DISTRIBUTING RESERVOIR.

The distributing reservoir should, in my judgment, have such an elevation or flow line as to give not less than 115 feet elevation for the hydraulic grade line at the

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deposito. It would be very convenient to have the filter beds and the clear-water reservoir together, and it may be found that there is a good site for a distributing reservoir upon the high land east of the deposito, where the prism of water may be located, so as to have the highest efficiency in serving the distribution system. It may be found desirable in the interests of economy to build one-half of the reservoir only at first, in which case it seems proper to give the one-half a capacity of 50,000,000 gallons.

RECAPITULATION.

The following is a recapitulation of the recommendations in this report:

1. The building of a storage reservoir at the gorge.

2. The building of a conduit line to the filters.

3. The building of open sand filters of a present capacity of about 10,000,000 gallons per day.

4. The building of a covered distributing reservoir of not less than 50,000,000 gallons present capacity.

5. The fixing of the hydraulic gradients so as to produce a pressure of not less than 115 feet at about the situation of the present "deposito."

The above is a practical indorsement, as far as my judgment goes, of the very excellent plan outlined by Major Case in his report, the principal exception being the imperative necessity for constructing the filters at the same time with the other works, and I think that developments which have occurred since Major Case made his report will lead him to agree with me that this part of the work should not be postponed. I can not close this report without expressing my obligations to Major Case for the kindness and promptness with which he has aided me in my investigations and for the courtesy and consideration shown me by many members connected with the city government.

Very faithfully, yours,

DESMOND FITZ GERALD, Consulting Engineer.

President Municipal Board of Manila.

Hon. ARSENIO C. HERRERA,

Maj. JAMES F. CASE, City Engineer.

DEPARTMENT OF THE INTERIOR,
BUREAU OF GOVERNMENT LABORATORIES,
Manila, P. I., March 14, 1904.

SIR: I have the honor to report as follows in regard to the work undertaken by the laboratories for the examination of the water in the Mariquina River in conjunction with its present work in examining the tap water. An extract from the report of Dr. W. E. Musgrave, of the biological laboratory, containing all points bearing on the water supply, is as follows:

"The expedition left Manila at 2.30 p. m. March 5 in two government wagons and arrived at Montalbon about 8.30 of the same day. Next morning a visit was made through the 'gorge' to the proposed site of the dam for the new water supply. From here the return trip was commenced, arriving in Manila about 11 p. m. Sunday, March 6.

"Samples of water for culture for both bacteria and protozoa were taken just below the junction of the two streams which form the Mariquina River at the site of the new dam; at Montalbon, San Mateo and Santolan.

"The samples for bacteriologic examination were placed on ice soon after being taken and were kept cold until Monday morning, when cultures were made.

"Cultures were made at the same time from fresh samples of water from a city

tap.

"The sample for colony count made at the head of the river was unfortunately contaminated; for the others the bacteria were as follows:

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"To the director of the biological laboratory and forwarded to the superintendent of government laboratories.

"These counts were carefully made from a large number of plates and represent quite accurately the bacteria in the samples taken. I can not satisfactorily explain the low count in the sample from San Mateo. Some growths may have occurred in the samples during twelve to eighteen hours between the time they were taken and the time plates were made, notwithstanding they were kept packed on ice during this time.

"No classification of the bacteria has been attempted. They are for the most part very free-growing organisms and a considerable number are pigment producers. One of these latter, which has been found in all the plates, is a large, yellow pigment producing bacillus, not pathogenic for laboratory animals, but which has been found a most uniformly satisfactory symbiotic organism for the cultivation of amoebas in artificial media.

"Cultures for amoebas made from the same places as the bacteria already mentioned, and in addition one culture from the head of the Mariquina River, all showed numerous amoebas after the usual length of time, and some of these protozoa are now being further worked out.

"I know of no satisfactory method of determining actual numbers of amoebas as in the case of bacteria, but they are apparently quite numerous throughout the water

course.

"From a sanitary standpoint there can be no question of doubt about the advisability of changing the source of the water supply, and the judgment shown in the selection of the proposed new site is equally apparent.

"As to the present location it has not, so far as I can see, a single point in its favor. The water course is through a very fertile valley, which contains probably 50,000 human beings and animals. It is traversed by several small streams, which come from the mountains in various places and are all tributaries of the Mariquina River above the intake. To secure even a semblance of sanitation out of this supply would not only necessitate the removal of human and animal habitation from the valley and a large outlay of money to remove rank vegetation, but would require similar care for several of the smaller streams well into the foothills at several points. And finally, above all, to keep these conditions, once they were obtained, would require a constant guard over a very large area.

"In my drive from Santolan to Montalbon I saw five dead animals in varying stages of putrefaction lying in the river or its branches. Hogs, cattle, and other animals use the river as watering places, and human beings use it for bathing and laundry purposes and it acts as an open sewer for much of the offal of several barrios.

"In Montalbon I asked a sentry on duty to show me the place used as a watercloset, and was conducted to the side of a little hill containing considerable human feces. This place drained directly into the river a short distance away.

"The method of disposing of the dead and many other less important but objectionable features need hardly be noted here.

"The proposed new site for the water supply is, on the other hand, free from many of the objections to the present one, and is, on the whole, probably as satisfactory a location as could be found within a reasonable distance of Manila. The valley is narrow and the mountains high and steep on both sides. There are but few animals and very little human traffic in the region. There is, however, considerable vegetation, and a small town, Boso-boso, is situated on one branch a few miles above the proposed reservoir.

"As much as possible of the vegetation and all animal life should be removed from the entire watershed to bring the city supply within the bounds of probable safety. "With ordinary precautions the danger from bacteria in a water supply obtained from the proposed location would probably be very remote. In furnishing a safe water supply to Manila, however, another factor as important as the bacteria should be considered. Amoebas play an important role in the invalidism of the city's popu lation, and it has recently been shown in the laboratory that some of the pathogenic amo bas are found in the present water supply.

"I do not affirm that all amoebas are pathogenic, but at the present time no practical means are known by which the pathogenic may be separated. The only safe sanitary deduction is, therefore, to regard them as all dangerous.

"It has already been shown in this report that the water above the proposed new reservoir contains these parasites and they must therefore enter into our considerations. To limit the danger from amoebas in the water supply, one or both of two methods suggest themselves.

"First. Limit the number of amoebas and bacteria in the reservoir by removing all possible organic matter from the watershed.

"Second. Accomplish the same result or reenforce the first by a method of filtration.

"Recent unpublished work in this laboratory by Mr. Clegg and myself has shown that within certain limits amoebas are adaptable, and that this varying degree of pathogenicity is influenced by the environment of the organism. It is apparently increased by passage through the animal organism, and it is likely also to be influenced by the class of bacteria and other substances with which it may be associated. This work has progressed far enough to indicate that the further and longer removed from animal organic matter and possibly from some bacteria quite common in man the less likely will the amoebas be pathogenic to human beings on direct inoculation. This statement is offered as an additional reason for a complete removal of animal life from the proposed new watershed.

"The amoebas isolated from and above the proposed new reservoir will be studied more in detail and an additional report submitted if it is so desired.

"In closing I wish to emphasize that provisions for a safe water supply for Manila must include methods for removal of animal parasites which are present in the Mariquina River and its tributaries."

The table of the chemical examination, which is inclosed, shows the composition. of the water.

The results given above would indicate that in the future investigations the following course should be adopted. A model cross section of the filter which it is proposed to use should be made in a glass tube of sufficient diameter, which can be furnished by the laboratories, and tap water will then be run through the filter for a long time. The water taken from the lower end will then be examined immediately after installation, and at intervals afterwards, in order to determine whether the amoebas will finally force passage through or not. This will experimentally determine the efficiency of the filters and also whether they can be kept in use for any considerable length of time and how often cleaning must take place.

It is also suggested that the laboratories make a second expedition to the source of the water supply at the beginning of the rainy season for the purpose of determining what influence the rains will have upon the condition of the water supply. It is requested that the city engineer cooperate with the laboratories in preparing a model of the filter to be used, and also when the rains begin assist in sending a second expedition to the source of the supply. The laboratories will send a botanist above Montalbon as soon as possible to study the vegetation in the river.

I am, very respectfully,

PAUL C. FREER, Superintendent Government Laboratories.

DEPARTMENT OF ENGINEERING AND PUBLIC WORKS,
OFFICE OF CITY ENGINEER,

Manila, April 23, 1904.

The SECRETARY MUNICIPAL BOARD, Manila, P. I. SIR: Mr. Desmond FitzGerald, consulting engineer, has kindly furnished me with an advance copy of his report of the plans of the proposed water system for the city of Manila, and I desire to present the following observations, which may be considered supplementary to my original formal report:

In the first place, I desire to express my pleasure at the opportunity of being associated with Mr. FitzGerald in this work. The thoroughness of his investigations and the value of his advice in the discussions we have had, as well as his unfailing courtesy, have made our relations most pleasant and profitable to me. It is especially gratifying also to have his distinct and complete approval of my plans.

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Taking Mr. FitzGerald's report by paragraph, it will be noticed that we agree as to the quantity of water to be supplied under the head of "Future requirements." The Source of supply "selected by me meets Mr. FitzGerald's entire approval. The "Watershed" and "Proposed forest reserve" are agreed to. Mr. FitzGerald's notes on "Rainfall and storage" agree very closely to my own. Mr. FitzGerald assumes somewhat more rigid conditions than I did, which may be best described by stating that my computations were based on the assumption that the three driest seasons during the observed period might occur consecutively, while Mr. FitzGerald's more rigid assumption is that the driest year of the entire observed period might occur for three consecutive years. Mr. FitzGerald's storage results are therefore somewhat in excess of my own, though I wish to call attention to the fact that the "Storage reservoir" as designed by me is still of ample capacity should Mr. FitzGerald's assumption become an actual fact.

It will be noticed that the design of the dam at the gorge is approved both as to location and section. As Mr. FitzGerald states, all that man can do will have been

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