WHAT WATERS REQUIRE FILTRATION?

From the nature of the case a satisfactory general answer to this question cannot be given, but a few suggestions may be useful.

In the first place, ground-waters obviously do not require filtration: they have already in most cases been thoroughly filtered in the ground through which they have passed, and in the exceptional cases, as, for instance, an artesian well drawing water through fissures in a ledge from a polluted origin, a new supply will generally be chosen rather than to attempt to improve so doubtful a raw material.

River-waters should be filtered. It cannot be asserted that there are no rivers in mountainous districts in which the water is at once clear and free from pollution, and suitable in its natural state for water-supply; but if so, they are not common, least of all in the regions where water-supplies are usually required. The use of river-waters in their natural state or after sedimentation only, drawn from such rivers as the Merrimac, Hudson, Potomac, Delaware, Schuylkill, Ohio, and Mississippi, is a filthy as well as an unhealthy practice, which ought to be abandoned.

The question is more difficult in the case of supplies drawn from lakes or storage reservoirs. Many such supplies are grossly polluted and should be either abandoned or filtered. Others are subject to algæ growths, or are muddy, and would be much improved by filtration. Still others are drawn either from unpolluted water-sheds, or the pollution is so greatly diluted and reduced by storage that no known disadvantage results from their use.

In measuring the effects of the pollution of water-supplies, the typhoid-fever death-rate is a most important aid. Not that typhoid fever is the sole evil resulting from polluted water, but because it is also a very useful index of other evils for which corresponding statistics cannot be obtained, as, for instance, the causation of diarrhœal diseases or the danger from invasion by cholera.

I think we shall not go far wrong at the start to confine our attention to those cities where there are over 25 deaths from typhoid fever per 100,000 of population. This will at once throw out of consideration a large number of relatively good supplies, including those of New York and Brooklyn. It is not my idea that none of these supplies cause disease. Many of them, as for instance that of New York, are known to receive sewage, and it is an interesting question worthy of most careful study whether there are cases of sickness resulting from this pollution. The point that I wish to make now is simply that in those cases the death-rate itself is evidence that, with existing conditions of dilution and storage, the resulting damage of which we have knowledge is not great enough to justify the expense involved by filtration.

In this connection it should not be forgotten that, especially with very small watersheds, there may be a danger as distinct from present damage which requires consideration. Thus a single house or groups of houses draining into a supply may not appreciably affect it for years, until an outbreak of fever on the water-shed results in infecting the water with the germs of disease and in an epidemic in the city below. This danger decreases with increasing size of the water-shed and volume of the water with which any such pollution would be mixed, and also with the population draining into the water, as there is a probability that the amount of infection continually added from a considerable town will not be subject to as violent fluctuation as that from only a few houses.

Thus in Plymouth, Pa., in 1885, there were 1104 cases of typhoid fever and 114 deaths among a population of 8000, as the result of the discharge of the dejecta from a single typhoid patient into the water of a relatively small impounding reservoir. The cost of this epidemic was calculated with unusual care. The care of the sick cost in cash $67,100.17, and the loss of wages for those who recovered amounted to $30,020.08. The 114 persons who died were earning before their sickness at the rate of $18,419.52 annually.

Such an outbreak would hardly be possible with the Croton water-shed of the New York water-supply, on account of the great dilution and delay in the reservoirs, but it must be guarded against in small supplies.

Of the cities having more than 25 deaths per 100,000 from typhoid fever, some will no doubt be found where milk epidemics or other special circumstances were the cause; but I believe in a majority of them, and in nearly all cases where the rate is year after year considerably above that figure, the cause will be found in the water-supply. Investigation should be made of this point; and if the water is not at fault, the responsibility should be located. If the water is guilty, it should be either purified or a new supply obtained.

CHAPTER XIV.
WATER-SUPPLY AND DISEASE—CONCLUSIONS.

One of the most characteristic and uniform results of the direct pollution of public water-supplies is the typhoid fever which results among the users of the water. In the English and German cities with almost uniformly good drinking-water, typhoid fever is already nearly exterminated, and is decreasing from year to year. American cities having unpolluted water-supplies have comparatively few deaths from this cause, although the figures never go so low as in Europe, perhaps on account of the fresh cases which are always coming in from less healthy neighborhoods in ever-moving American communities. In other American cities the death-rates from typhoid fever are many times what they ought to be and what they actually are in other cities, and the rates in various places, and in the same place at different times, bear in general a close relation to the extent of the pollution of the drinking-water. The power of suitable filtration to protect a city from typhoid fever is amply shown by the very low death-rates from this cause in London, Berlin, Breslau, and large numbers of other cities drawing their raw water from sources more contaminated than those of any but the very worst American supplies, and by the marked and great reductions in the typhoid-fever death rates which have followed at once the installation of filters at Zürich, Switzerland; Hamburg, Germany; Lawrence, Mass., and other places.

The following is a list of the cities of 50,000 inhabitants and upward in the United States, with deaths from typhoid fever and the sources of their water-supplies. The deaths and populations are from the U. S. Census for 1890; the sources of the water-supplies, from the American Water-Works Manual for the same year. Four cities of this size—Grand Rapids, Lincoln, St. Joseph, and Des Moines—are not included in the census returns of mortality. Two cities with less than 50,000 inhabitants with exceptionally high death-rates have been included, and at the foot of the list are given corresponding data for some large European cities for 1893.

TYPHOID FEVER DEATH-RATES AND WATER-SUPPLIES OF CITIES.
City.Population.Deaths from
Typhoid
Fever.		Water-supply.
Total.Per
100,000
living.
Birmingham26,17869264Five Mile Creek
1.Denver106,713232217North Platte River and wells
2.Allegheny105,287192182Allegheny River
3.Camden58,31377132Delaware River
4.Pittsburg238,617304127Allegheny and Monongahela rivers
Lawrence44,65454121Merrimac River
5.Newark181,830181100Passaic River
6.Charleston54,9555498Artesian wells yielding 1,600,000 gallons daily
7.Washington230,39220087Potomac River
8.Lowell77,6966482Merrimac River
9.Jersey City163,00313482Passaic River
10.Louisville161,12912276Ohio River
11.Philadelphia1,046,96477074Delaware and Schuylkill rivers
12.Chicago1,099,85079472Lake Michigan
13.Atlanta65,5334772South River
14.Albany94,9236771Hudson River
15.Wilmington61,4314370Brandywine Creek
16.St. Paul133,1569269Lakes
17.Troy60,9564269Hudson River and impounding reservoirs
18.Los Angeles50,3953467Los Angeles River and springs
19.Nashville76,1684964Cumberland River
20.Cleveland261,35316463Lake Erie
21.Richmond81,3885061James River
22.Hartford53,2303260Connecticut River and impounding reservoir
23.Fall River74,3984459Watupa Lake
24.Minneapolis164,7389457Mississippi River
25.San Francisco298,99716656Lobus Creek, Lake Merced, and mountain streams
26.Indianapolis105,4365754White River
27.Cincinnati296,90815151Ohio River
28.Memphis64,4953351Artesian Wells
29.Reading58,6612949Maiden Creek and Springs
30.Baltimore434,43920247Impounding reservoir
31.Omaha140,4526345Missouri River
32.Columbus88,1503843Surface-water and wells
33.Providence132,1465340Pawtuxet River
34.Kansas City132,7165340Missouri River
35.Rochester133,8965339Hemlock and Candice lakes
36.Evansville50,7562039Ohio River
37.Boston448,47717439Impounding reservoirs
38.Toledo81,4342936Maumee River
39.Cambridge70,0282434Impounding reservoir
40.St. Louis451,77014532Mississippi River
41.Scranton75,2152432Impounding reservoir
42.Buffalo255,6648031Niagara River
43.Milwaukee204,4686130Lake Michigan
44.New Haven81,2982227Impounding reservoir
45.Worcester84,6552226Impounding reservoir
46.Paterson78,3472026Passaic River (higher up)
47.Dayton61,2201525Wells
48.Brooklyn806,34319424Wells, ponds, and impounding reservoirs
49.New York1,515,30134823Impounding reservoir
50.Syracuse88,1431820Impounding reservoir and springs
51.New Orleans242,0394519Mississippi River
52.Detroit205,8764019Detroit River
53.Lynn55,727916Impounding reservoir
54.Trenton57,458916Delaware River
London4,306,41171917Filtered Thames and Lea rivers and 1⁄4 from wells
Glasgow667,88313820Loch Katrine
Paris2,424,70560925Spring water
Amsterdam437,8926916Filtered dune-water
Rotterdam222,233125Filtered Maas River
Hague169,82832Filtered dune-water
Berlin1,714,9381619Filtered Havel and Spree rivers
Hamburg634,87811518Filtered Elbe River
Breslau353,5513711Filtered Oder River
Dresden308,930145Ground-water
Vienna1,435,9311047Spring-water

Any full discussion of these data would require intimate acquaintances with the various local conditions which it is impossible to take up in detail here, but some of the leading facts cannot fail to be instructive.

Each of the places having over 100 deaths per 100,000 from typhoid fever used unfiltered river-water. Lower in the list, but still very high, Charleston, said to have been supplied only from artesian wells, had an excessive rate; but the reported water-consumption is so low as to suggest that private wells or other means of supply were in common use. Chicago and Cleveland both drew their water from lakes where they were contaminated by their own sewage. St. Paul’s supply came from ponds, of which I do not know the character. With these exceptions all of the 22 cities with over 50,000 inhabitants, at the head of the list, had unfiltered river-water.

The cities supplied from impounding reservoirs as a rule had lower death rates and are at the lower end of the list, together with some cities taking their water supplies from rivers or lakes at points where they were subject to only smaller or more remote infection. Only three of the American cities in the list were reported as being supplied entirely with ground-water.

It is not my purpose to make too close comparisons between the various cities on the list; some of them may have been influenced by unusual local conditions in 1890. Others have in one way or another improved their water-supplies since that date, and there are several cities in which I know the present typhoid-fever death-rates to be materially lower than those of 1890 given in the table. On the other hand, it is equally true that a number of cities, including some of the larger ones, have since had severe epidemics of typhoid fever which have given very much higher rates than those for 1890.

These fluctuations would change the order of cities in the list from year to year; they would not change the general facts, which are as true to-day as they were in 1890. Nearly all of the great cities of the United States are supplied with unfiltered surface-waters, and a great majority of the waters are taken from rivers and lakes at points where they are polluted by sewage. The death-rates from typhoid fever in those cities, whether they are compared with better supplied cities of this country, or with European cities, are enormously high.

Such rates were formerly common in European cities, but they have disappeared with better sanitary conditions. The introduction of filters has often worked marvellous changes in Europe, and in Lawrence the improvement in the city’s health with filtered water was prompt and unquestionable. There is every reason to believe that the general introduction of better water in American cities will work corresponding revolutions; and looking at it from a merely money standpoint, the value of the lives and the saving of the expenses of sickness will pay handsomely when compared with the cost of good water.

The reasons for believing that cholera is caused by polluted water are entirely similar to those in the case of typhoid fever. It was no accident that the epidemic of cholera which caused the death of 3400 persons followed the temporary supply of unfiltered water by the East London Water Company in 1866, while the rest of London remained nearly free, or that the only serious outbreak of cholera in Western Europe in 1892 was at Hamburg, which was also the only city in Germany which used raw river-water. This latter caused the sickness of 20,000 and the death of over 8000 people within a month, and an amount of suffering and financial loss, with the panics which resulted, that cannot be estimated, but that exceeded many times the cost of the filters which have since been put in operation. Hamburg had several times before suffered severely from cholera, and the removal of this danger was a leading, although not the sole, motive for the construction of filters.

How little cities supplied with pure water have to dread from cholera is shown by the experience of Altona and other suburbs of Hamburg with good water-supplies, which had but few cases of cholera not directly brought from the latter place, and by the experience of England, which maintained uninterrupted commercial intercourse with the plague-stricken city, absolutely without quarantine, and, notwithstanding a few cases which were directly imported, the disease gained no foothold in England.

I do not know of a single modern European instance where a city with a good water-supply not directly infected by sewage has suffered severely from cholera. I shall leave to others more familiar with the facts the discussion of what happened before the introduction of modern sanitary methods, as well as of the present conditions in Asia; although I believe that in these cases also there is plenty of evidence as to the part water plays in the spread of the disease.

A considerable proportion of the water-supplies of the cities of the United States are so polluted that in case cholera should gain a foothold upon our shores we have no ground for hoping for the favorable experience of the English cities rather than the plague of Hamburg in 1892.

The fæces from a man contain on an average perhaps 1,000,000,000 bacteria per gram,[47] most of them being the normal bacilli of the intestines, Bacillus coli communis. Assuming that a man discharges 200 grams or about 7 ounces of fæces daily, this would give 200,000,000,000 bacteria discharged daily per person. The number of bacteria actually found in American sewage is usually higher, often double this number per person; but there are other sources of bacteria in sewage, and in addition growths or the reverse may take place in the sewers, according to circumstances.

This number of bacteria in sewage is so enormously large that the addition of the sewage from a village or city to even a large river is capable of affecting its entire bacterial composition. Thus taking the population of Lowell in 1892 at 85,000, and the average daily flow of the Merrimac at 6000 cubic feet per second, and assuming that 200,000,000,000 bacteria are discharged daily in the sewage from each person, they would increase the number in the river by 1160 per cubic centimeter, or about 300,000 in an ordinary glass of water. The average number found in the water eight miles below, at the intake of the Lawrence water-works, was more than six times as great as this, due in part to the sewage of other cities higher up.

There is every reason to believe that the bulk of these bacteria were harmless to the people of Lawrence, who drank them; but some of them were not. Fæces of people suffering from typhoid fever contain the germs of that disease. What proportion of the total number of bacteria in such fæces are injurious is not known; but assuming that one fourth only of the total number are typhoid germs, and supposing the fæces of one man to be evenly mixed with the whole daily average flow of the river, it would put one typhoid germ into every glass of water at the Lawrence intake, and at low water several times as many proportionately would be added. This gives some conception of the dilution required to make a polluted water safe.

One often hears of the growth of disease-germs in water, but as far as the northern United States and Europe are concerned there is no evidence whatever that this ever takes place. There are harmless forms of bacteria which are capable of growing upon less food than the disease-germs require and they often multiply in badly-polluted waters. Typhoid-fever germs live for a longer or shorter period, and finally die without growth. The few laboratory experiments which have seemed to show an increase of typhoid germs in water have been made under conditions so widely different from those of natural watercourses that they have no value.[48]

The proportionate number of cases of typhoid fever among the users of a polluted water varies with the number of typhoid germs in the water. Excessive pollution causes severe epidemics or continued high death-rates according as the infection is continued or intermittent. Slight infection causes relatively few cases of fever. Pittsburg and Allegheny, taking their water-supplies from below the outlets of some of their own sewers, have suffered severely (103.2 and 127.4 deaths from typhoid fever annually per 100,000, respectively, from 1888 to 1892). Wheeling, W. Va., with similar conditions in 1890, was even worse, a death rate of 345 per 100,000 from this cause being reported, while Albany had only comparatively mild epidemics from the less directly and grossly polluted Hudson. Lawrence and Lowell, taking their water from the Merrimac, both had for many years continued excessive rates, increasing gradually with increasing pollution; and the city having the most polluted source had the higher rate.

In Berlin and Altona, in winter, with open filters, epidemics of typhoid fever followed decreased efficiency of filtration, but the epidemics were often so mild that they would have entirely escaped observation under present American conditions. Chicago has for years suffered from typhoid fever, and the rate has fluctuated, as far as reliable information can be obtained, with the fluctuations in the pollution of the lake water. An unusual discharge of the Chicago River results in a higher death-rate. Abandoning the shore inlet near the mouth of the Chicago River in 1892, resulted in the following year in a reduction of 60 per cent in the typhoid fever death-rate.[49] This reduction shows, not that the present intakes are safe, but simply that they are less polluted than the old ones to an extent measured by the reduction in the death-rate.

It is not supposed that in an epidemic of typhoid fever caused by polluted water every single person contracts the disease directly by drinking the water. On the contrary, typhoid fever is often communicated in other ways. If we have in the first place a thousand cases in a city caused directly by the water, they will be followed by a large number of other cases resulting directly from the presence in the city of the first thousand cases. The conditions favoring this spread may vary in different wards, resulting in considerable local variations in the death-rates. Some persons also will suffer who did not drink any tap-water. These facts, always noted in epidemics, afford no ground for refusing to believe, in the presence of direct evidence, that the water was the cause of the fever. These additional cases are the indirect if not the direct result of the water. The broad fact that cities with polluted water-supplies as a rule have high typhoid-fever death-rates, and cities with good water-supplies do not (except in the occasional cases of milk epidemics, or where they are overrun by cases contracted in neighboring cities with bad water, as is the case with some of Chicago’s suburbs), is at once the best evidence of the damage from bad water and measure of its extent.

The conditions which remove or destroy the sewage bacteria in a water tend to make it safe. The most important of them are: (1) dilution; (2) time, allowing the bacteria to die (sunlight may aid in this process, although effective sunshine cannot reach the lower layer of turbid waters or through ice); (3) sedimentation, allowing them to go to the bottom, where they eventually die; and (4) natural or artificial filtration. In rivers, distance is mainly useful in affording time, and also, under some conditions, in allowing opportunities for sedimentation. Thus a distance of 500 miles requires a week for water travelling three miles an hour to pass, and will allow very important changes to take place. The old theory that water purifies itself in running a certain distance has no adequate foundation as far as bacteria are concerned. Some purification takes place with the time involved in the passage, but its extent has been greatly overestimated.

The time required for the bacteria to die simply from natural causes is considerable; certainly not less than three or four weeks can be depended upon with any confidence. In storage reservoirs this action is often considerable, and it is for this reason that American water-supplies from large storage reservoirs are, as a rule, much more healthy than those drawn from rivers or polluted lakes, even when the sources of the former are somewhat polluted. The water-supplies of New York and Boston may be cited as examples. In many other water-works operations the entire time from the pollution to the consumption of the water is but a few days or even less, and time does not materially improve water in this period.

Sedimentation removes bacteria only slowly, as might be expected from their exceedingly small size; and in addition their specific gravity probably is but slightly greater than that of water. The Lawrence reservoir, holding from 10 to 14 days’ supply, effected, by the combined effect of time and sedimentation, a reduction of 90 per cent of the bacteria in the raw water. In spite of this the city suffered severely and continuously from fever. It would probably have suffered even more, however, had it not been for this reduction. Nothing is known of the removal of bacteria by sedimentation from flowing rivers, but, considering the slowness with which the process takes place in standing water, it is evident that we cannot hope for very much in streams, and especially rapid streams, where the opportunities for sedimentation are still less favorable.

Filtration as practiced in Europe removes promptly and certainly a very large proportion of the bacteria—probably, under all proper conditions, over 99 per cent, and is thus much more effective in purification than even weeks of storage or long flows in rivers. The places using filtered water have, in general, extremely low death-rates from typhoid fever. The fever which has occurred at a few places drawing their raw water from greatly polluted sources has resulted from improper conditions which can be avoided, and affords no ground for doubt of the efficiency of properly conducted filtration.

Corresponding evidence has not yet been produced in connection with the mechanical filters which have been largely used in the United States; but the bacterial efficiencies secured with them, under proper conditions, and with enough coagulant, have been such as to warrant the belief that they also will serve to greatly diminish the danger from such infection, although they have not shown themselves equal in this respect to sand filters.

The main point is that disease-germs shall not be present in our drinking-water. If they can be kept out in the first place at reasonable expense, that is the thing to do. Innocence is better than repentance. If they cannot be kept out, we must take them out afterwards; it does not matter much how this is done, so long as the work is thorough. Sedimentation and storage may accomplish much, but their action is too slow and often uncertain. Filtration properly carried out removes bacteria promptly and thoroughly and at a reasonable expense.

APPENDICES.

APPENDIX I.
RULES OF THE GERMAN GOVERNMENT IN REGARD TO THE FILTRATION OF SURFACE-WATERS USED FOR PUBLIC WATER-SUPPLIES.

Rules somewhat similar to those of which a translation is given below were first issued by the Imperial Board of Health in 1892. These rules were regarded as unnecessarily rigid, and a petition was presented to the government signed by 37 water-works engineers and directors requesting a revision.[50] As a result a conference was organized consisting of 14 members.[51] Köhler presided, and Koch, Gaffsky, Werner, Günther, and Reincke represented the Imperial Board of Health. The bacteriologists were represented by Flügge, Wolffhügel, and Fränkel, while Beer, Fischer, Lindley, Meyer, and Piefke were the engineer members.

This conference prepared the 17 articles given below in the first days of January, 1894. A little later the first 16 articles were issued to all German local authorities, signed by Bosse, minister of the “Geistlichen,” and Haase, minister of the interior, and they are considered as binding upon all water-works using surface-water. The bacterial examinations were commenced April 1, 1894, by most of the cities which had not previously had them.

Although the articles do not deal with rate of filtration, or the precautions against snow and ice, they have a very great interest both because they are an official expression, and on account of the personal standing of the men who prepared them.

§ 1. In judging of the quality of a filtered surface-water the following points should be especially observed:

a. The operation of a filter is to be regarded as satisfactory when the filtrate contains the smallest possible number of bacteria, not exceeding the number which practical experience has shown to be attainable with good filtration at the works in question. In those cases where there are no previous records showing the possibilities of the works and the influence of the local conditions, especially the character of the raw water, and until such information is obtained, it is to be taken as the rule that a satisfactory filtration will never yield an effluent with more than about 100 bacteria per cubic centimeter.

b. The filtrate must be as clear as possible, and, in regard to color, taste, temperature, and chemical composition, must be no worse than the raw water.

§ 2. To allow a complete and constant control of the bacterial efficiency of filtration, the filtrate from each single filter must be examined daily. Any sudden increase in the number of bacteria should cause a suspicion of some unusual disturbance in the filter, and should make the superintendent more attentive to the possible causes of it.

§ 3. Filters must be so constructed that samples of the effluent from any one of them can be taken at any desired time for the bacteriological examination mentioned in § 1.

§ 4. In order to secure uniformity of method, the following is recommended as the standard method for bacterial examination:

The nutrient medium consists of 10 per cent meat extract gelatine with peptone, 10 cc. of which is used for each experiment. Two samples of the water under examination are to be taken, one of 1 cc. and one of 1⁄2 cc. The gelatine is melted at a temperature of 30° to 35° C., and mixed with the water as thoroughly as possible in the test-tube by tipping back and forth, and is then poured upon a sterile glass plate. The plates are put under a bell-jar which stands upon a piece of blotting-paper saturated with water, and in a room in which the temperature is about 20° C.

The resulting colonies are counted after 48 hours, and with the aid of a lens.

If the temperature of the room in which the plates are kept is lower than the above, the development of the colonies is slower, and the counting must be correspondingly postponed.

If the number of colonies in 1 cc. of the water is greater than about 100, the counting must be done with the help of the Wolffhügel’s apparatus.

§ 5. The person entrusted with the carrying-out of the bacterial examinations must present a certificate that he possesses the necessary qualifications, and wherever possible he shall be a regular employé of the water-works.

§ 6. When the effluent from a filter does not correspond to the hygienic requirements it must not be used, unless the cause of the unsatisfactory work has already been removed during the period covered by the bacterial examinations.

In case a filter for more than a very short time yields a poor effluent, it is to be put out of service until the cause of the trouble is found and corrected.

It is, however, recognized from past experience that sometimes unavoidable conditions (high water, etc.) make it impossible, from an engineering standpoint, to secure an effluent of the quality stated in § 1. In such cases it will be necessary to get along with a poorer quality of water; but at the same time, if the conditions demand it (outbreak of an epidemic, etc.), a suitable notice should be issued.

§ 7. Every single filter must be so built that, when an inferior effluent results, which does not conform to the requirements, it can be disconnected from the pure-water pipes and the filtrate allowed to be wasted, as mentioned in § 6. This wasting should in general take place, so far as the arrangement of the works will permit it:

(1) Immediately after scraping a filter; and

(2) After replacing the sand to the original depth.

The superintendent must himself judge, from previous experience with the continual bacterial examinations, whether it is necessary to waste the water after these operations, and, if so, how long a time will probably elapse before the water reaches the standard purity.

§ 8. The best sand-filtration requires a liberal area of filter-surface, allowing plenty of reserve, to secure, under all local conditions, a moderate rate of filtration adapted to the character of the raw water.

§ 9. Every single filter shall be independently regulated, and the rate of filtration, loss of head, and character of the effluent shall be known. Also each filter shall, by itself, be capable of being completely emptied, and, after scraping, of having filtered water introduced from below until the sand is filled to the surface.

§ 10. The velocity of filtration in each single filter shall be capable of being arranged to give the most favorable results, and shall be as regular as possible, quite free from sudden changes or interruptions. On this account reservoirs must be provided large enough to balance the hourly fluctuation in the consumption of water.

§ 11. The filters shall be so arranged that their working shall not be influenced by the fluctuating level of the water in the filtered-water reservoir or pump-well.

§ 12. The loss of head shall not be allowed to become so great as to cause a breaking through of the upper layer on the surface of the filter. The limit to which the loss of head can be allowed to go without damage is to be determined for each works by bacterial examinations.

§ 13. Filters shall be constructed throughout in such a way as to insure the equal action of every part of their area.

§ 14. The sides and bottoms of filters must be made water-tight, and special pains must be taken to avoid the danger of passages or loose places through which the unfiltered water on the filter might find its way to the filtered-water channels. To this end special pains should be taken to make and keep the ventilators for the filtered-water channels absolutely tight.

§ 15. The thickness of the sand-layer shall be so great that under no circumstances shall it be reduced by scraping to less than 30 cm. (= 12 inches), and it is desirable, so far as local conditions allow, to increase this minimum limit.

Special attention must be given to the upper layer of sand, which must be arranged and continually kept in the condition most favorable for filtration. For this reason it is desirable that, after a filter has been reduced in thickness by scraping and is about to be refilled, the sand below the surface, as far as it is discolored, should be removed before bringing on the new sand.

§ 16. Every city in the German empire using sand-filtered water is requested to make a quarterly report of its working results, especially of the bacterial character of the water before and after filtration, to the Imperial Board of Health (Kaiserlichen Gesundheitsamt), which will keep itself in communication with the commission chosen by the water-works engineers in regard to these questions; and it is believed that after such statistical information is obtained for a period of about two years some farther judgments can be reached.

§ 17. The question as to the establishment of a permanent inspection of public water-works, and, if so, under what conditions, can be best answered after the receipt of the information indicated in § 16.

APPENDIX II.
EXTRACTS FROM “BERICHT DES MEDICINAL-INSPECTORATS DES HAMBURGISCHEN STAATES FÜR DAS JAHR 1892.”

The following are translations from Dr. Reincke’s most valuable report upon the vital statistics of Hamburg for 1892. I much regret that I am unable to reproduce in full the very complete and instructive tables and diagrams which accompany the report.

Diarrhœa and Cholera Infantum (page 10). “It is usually assumed that the increase of diarrhœal diseases in summer is to be explained by the high temperature, especially by the action of the heat upon the principal food of infants—milk. Our observations, however, indicate that a deeper cause must be sought.” (Tables and diagrams of deaths from cholera infantum by months for Hamburg and for Altona with the mean temperatures, 1871-1892.)

“From these it appears that the highest monthly mortality of each year in Hamburg occurred 7 times in July, 13 times in August, and 3 times in September, and substantially the same in Altona. If one compares the corresponding temperatures, it is found that in the three years 1886, 1891, and 1892, with high September mortalities, especially the first two of them, had their maximum temperature much earlier, in fact earlier than usual. Throughout, the correspondence between deaths and temperatures is not well marked. Repeated high temperatures in May and June have never been followed by a notable amount of cholera infantum, although such periods have lasted for a considerable time. For example, toward the end of May, 1892, for a long time the temperature was higher than in the following August, when the cholera infantum appeared.

“The following observations are still more interesting. As is seen from the diagram, in addition to the annual rise in summer there is also a smaller increase in the winter, which is especially marked in Altona. In 1892 this winter outbreak was greater than the summer one, and nearly as great in 1880 and in 1888. The few years when this winter increase was not marked, 1876-7, 1877-8, 1881-2, 1883-4, were warm winters in which the mean temperature did not go below the freezing-point. It is also to be noted that the time of this winter outbreak is much more variable than that of the summer one. In 1887 the greatest mortality was in November; in 1889 in February; in other years in December or January, and in Altona, in 1886 and 1888, in March, which is sufficient evidence that it was not the result of Christmas festivities.

“Farther, the winter diarrhœa of Hamburg and of Altona are not parallel as is the case in summer. In Hamburg the greatest mortality generally comes before New Year’s; in Altona one to two months later.

“In Bockendahl’s Generalbericht über das öffentliche Gesundheitswesen der Provinz Schleswig-Holstein für das Jahr 1870, page 10, we read: ‘Yet more remarkable was an epidemic of cholera infantum in Altona in February which proved fatal to 43 children. These cases were distributed in every part of the city, and could not be explained by the health officer until he ascertained that the water company had supplied unfiltered water to the city. This occurred for a few days only in January, and was the only time in the whole year that unfiltered Elbe water was delivered. However little reason there may be to believe that there was a connection between these circumstances, future interruptions of the service of filtered water should be most critically watched, as only in this way can reliable conclusions be reached. Without attempting to draw any scientific conclusions from the fact, I cannot do less than record that, prior to the outbreak of cholera on August 20, 1871, unfiltered together with filtered water had been supplied to the city August 11 to 18. The action of the authorities was then justified when they forbade in future the supply of unfiltered water except in cases of most urgent necessity, as in case of general conflagration; and in such a case, or in case of interruption due to broken pipes, that the public should be suitably warned.’

“The author of this paragraph, Dr. Kraus, became later the health officer of Hamburg, and in an opinion written by him in 1874, and now before me, he most earnestly urged the adoption of sand-filtration in Hamburg, and cites the above observations in support of his position. In the annual report of vital statistics of Hamburg for 1875 he says that it is quite possible that the addition of unfiltered Elbe water to milk is the cause of the high mortality from cholera infantum, as compared with London, and this idea was often afterward expressed by him. Since then so much evidence has accumulated that his view may fairly be considered proved.

“For the information of readers not familiar with local conditions, a mention of the sources of the water-supplies up to the present time used by Hamburg and Altona will be useful. Both cities take their entire water-supplies from the Elbe—Altona from a point about 7 miles below the discharge of the sewage of both cities, Hamburg from about 7 miles above. The raw water at Altona is thus polluted by the sewage from the population of both cities, having now together over 700,000 inhabitants, and contains in general 20,000 to 40,000 or more bacteria per cubic centimeter. The raw water of Hamburg has, however, according to the time of year and tide, from 200 to 5000, but here also occasionally much higher numbers are obtained when the ebb tide carries sewage up to the intake. How often this takes place is not accurately known, but most frequently in summer when the river is low, more rarely in winter and in times of flood. Recent bacterial examinations show that it occurs much more frequently than was formerly assumed from float experiments. This water is pumped directly to the city raw, while that for Altona is carefully filtered.

“Years ago I expressed the opinion that the repeated typhoid epidemics in Altona stood in direct connection with disturbances of the action of the filters by frost, which result in the supply of insufficiently purified water. Wallichs in Altona has also come to this conclusion as a result of extended observation, and recently Robert Koch has explained the little winter epidemic of cholera in Altona in the same way, thus supporting our theory. When open filters are cleaned in cold, frosty weather the bacteria in the water are not sufficiently held back by the filters. Such disturbances of filtration not only preceded the explosive epidemics of typhoid fever of 1886, 1887, 1888, 1891, and 1892, and the cholera outbreaks of 1871 and 1893, but also the winter outbreaks of cholera infantum which have been so often repeated. It cannot be doubted that these phenomena bear the relation to each other of cause and effect. It is thus explained why in the warm winters no such outbreaks have taken place, and also why the cholera infantum in winter is not parallel in Hamburg and Altona.

“A farther support of this idea is furnished by Berlin, where in the same way frost has repeatedly interfered with filtration. In the following table are shown the deaths from diarrhœa and cholera infantum for a few winter periods having unusual increases in mortality in comparison with the bacteria in the water-supply.” (These tables show that in March, 1886, March, 1888, February-March, 1889, and February, 1891, high numbers of bacteria resulted from frost disturbance at the Stralau works, and in every case they were followed by greatly increased death-rates from diarrhœal diseases.—A. H.)

“No one who sees this exhibition can doubt that here also the supply of inadequately purified water has every time cost the lives of many children.” (100 to 400 or more each time.—A. H.) “Even more conclusive is the evidence, published by the Berlin Health Office, that this increase was confined to those parts of the city supplied from Stralau” (with open filters.—A. H.), “and that the parts supplied from the better Tegel works took no part in the outbreaks, which was exactly the case with the well-known typhoid epidemic of February and March, 1889.... It was also found that those children nursed by their mothers or by wet-nurses did not suffer, but only those fed on the milk of animals or other substitutes, and which in any case were mixed with more or less water.”

Under Cholera, page 28, he says: “The revised statistics here given differ slightly from preliminary figures previously issued and widely published.” (The full tables, which cannot be here reproduced, show 16,956 cases and 8605 deaths. 8146 of the deaths occurred in the month ending September 21. Of these, 1799 were under 5 years old; 776 were 5 to 15; 744, 15 to 25; 3520, 25 to 50; 1369, 50 to 70; and 397 over 70 or of unknown age. The bulk of the cases were thus among mature people, children, except very young children, suffering the least severely of any age class.)

“The epidemic began on August 16, in the port where earlier outbreaks have also had their origin. The original source of the infection has not been ascertained with certainty, but was probably from one of two sources. Either it came from certain Jews, just arrived from cholera-stricken Russia, who were encamped in large numbers near the American pier, or the infection came from Havre, where cholera had been present from the middle of July. Perhaps the germs came in ships in water-ballast which was discharged at Hamburg, which is so much more probable, as the sewage of Havre is discharged directly into the docks.

“It is remarkable that in Altona, compared to the total number of cases, very few children had cholera, while in the epidemic of 1871 the children suffered severely. This may be explained by supposing that the cholera of 1892 in Altona was not introduced by water, but by other means of infection....

“It is well known that the drinking-water (of Hamburg) is supposed to have been from the first the carrier of the cholera-germs. In support of this view the following points are especially to be noted:

“1. The explosive rapidity of attack. The often-compared epidemic in Munich in 1854, which could not have come from the water is characteristically different in that its rise was much slower and was followed by a gradual decline. In Hamburg, with six times as large a population, the height of the epidemic was reached August 27, only 12 days after the first cases of sickness, while in Munich 25 days were required. In Hamburg also the bulk of the cases were confined to 12 days, from August 25 to September 5, while in Munich the time was twice as long.

“2. The exact limit of the epidemic to the political boundary between Hamburg and Altona and Wandsbeck, which also agrees with the boundary between the respective water-supplies, while other differences were entirely absent. Hamburg had for 1000 inhabitants 26.31 cases and 13.39 deaths, but Altona only 3.81 cases and 2.13 deaths, and Wandsbeck 3.06 cases and 2.09 deaths.

“3. The old experience of cholera in fresh-water ports, and the analogy of many earlier epidemics. In this connection the above-mentioned epidemic of 1871 in Altona has a special interest, even though some of the conclusions of Bockendahl’s in his report of 1871 are open to objection. First there were 3 deaths August 3, which were not at once followed by others. Then unfiltered Elbe water was supplied August 11 to 18. On the 19th an outbreak of cholera extended to all parts of the city, which reached its height August 25 and 26, and afterwards gradually decreased. In all 105 persons died of cholera and 186 (179 of them children) of diarrhœa. In Hamburg, four times as large, only 141 persons died of cholera at this time, thus proportionately a smaller number. The conditions were then the reverse of those of 1892, an infection of the Altona water and a comparative immunity in Hamburg.

“It is objected that the cholera-germs were not found in the water in 1892. To my knowledge they were first looked for, and then with imperfect methods, in the second half of September. In the after-epidemics at Altona, they were found in the river-water by R. Koch by the use of better methods.

“It is quite evident that the germs were also distributed by other methods than by the city water, especially by dock-laborers who became infected while at their work and thus set up little secondary epidemics where they went or lived.... These laborers and sailors, especially on the smaller river-boats, had an enormously greater proportionate amount of cholera than others.... These laborers do not live exclusively near the water, but to a measure in all parts of the city.” (And in Altona and Wandsbeck.—A. H.)

“Altona had 5 deaths from cholera December 25 to January 4, and 19 January 23 to February 11, and no more. As noted above, this is attributed to the water-supply, and to defective filtration in presence of frost....

“The cholera could never have reached the proportion which it did, had the improvements in the drinking-water been earlier completed.”

Further accounts of the water-supplies of Altona and of Hamburg and of the new filtration works at the latter city are given in Appendices VII and VIII.

APPENDIX III.
METHODS OF SAND ANALYSIS
(From the Annual Report of the Massachusetts State Board of Health for 1892.)

A knowledge of the sizes of the sand-grains forms the basis of many of the computations. This information is obtained by means of mechanical analyses. The sand sample is separated into portions having grains of definite sizes, and from the weight of the several portions the relative quantities of grains of any size can be computed.

Collection of Samples.—In shipping and handling, samples of sand are best kept in their natural moist condition, as there is then no tendency to separation into portions of unequal-sized grains. Under no circumstances should different materials be mixed in the same sample. If the material under examination is not homogeneous, samples of each grade should be taken in separate bottles, with proper notes in regard to location, quantity, etc. Eight-ounce wide-necked bottles are most convenient for sand samples, but with gravels a larger quantity is often required. Duplicate samples for comparison after obtaining the results of analyses are often useful.

Separation into Portions having Grains of Definite Sizes.—Three methods are employed for particles of different sizes—hand-picking for the stones, sieves for the sands, and water elutriation for the extremely fine particles. Ignition, or determination of albuminoid ammonia, might be added for determining the quantity of organic matter, which, as a matter of convenience, is assumed to consist of particles less than 0.01 millimeter in diameter.

The method of hand-picking is ordinarily applied only to particles which remain on a sieve two meshes to an inch. The stones of this size are spread out so that all are in sight, and a definite number of the largest are selected and weighed. The diameter is calculated from the average weight by the method to be described, while the percentage is reckoned from the total weight. Another set of the largest remaining stones is then picked out and weighed as before, and so on until the sample is exhausted. With a little practice the eye enables one to pick out the largest stones quite accurately.

With smaller particles this process becomes too laborious, on account of the large number of particles, and sieves are therefore used instead. The sand for sifting must be entirely free from moisture, and is ordinarily dried in an oven at a temperature somewhat above the boiling-point. The quantity taken for analysis should rarely exceed 100-200 grams. The sieves are made from carefully-selected brass-wire gauze, having, as nearly as possible, square and even-sized meshes. The frames are of metal, fitting into each other so that several sieves can be used at once without loss of material. It is a great convenience to have a mechanical shaker, which will take a series of sieves and give them a uniform and sufficient shaking in a short time; but without this good results can be obtained by hand-shaking. A series which has proved very satisfactory has sieves with approximately 2, 4, 6, 10, 20, 40, 70, 100, 140, and 200 meshes to an inch; but the exact numbers are of no consequence, as the actual sizes of the particles are relied upon, and not the number of meshes to an inch.

It can be easily shown by experiment that when a mixed sand is shaken upon a sieve the smaller particles pass first, and as the shaking is continued larger and larger particles pass, until the limit is reached when almost nothing will pass. The last and largest particles passing are collected and measured, and they represent the separation of that sieve. The size of separation of a sieve bears a tolerably definite relation to the size of the mesh, but the relation is not to be depended upon, owing to the irregularities in the meshes and also to the fact that the finer sieves are woven on a different pattern from the coarser ones, and the particles passing the finer sieves are somewhat larger in proportion to the mesh than is the case with the coarser sieves. For these reasons the sizes of the sand-grains are determined by actual measurements, regardless of the size of the mesh of the sieve.

It has not been found practicable to extend the sieve-separations to particles below 0.10 millimeter in diameter (corresponding to a sieve with about 200 meshes to an inch), and for such particles elutriation is used. The portion passing the finest sieve contains the greater part of the organic matter of the sample, with the exception of roots and other large undecomposed matters, and it is usually best to remove this organic matter by ignition at the lowest possible heat before proceeding to the water-separations. The loss in weight is regarded as organic matter, and calculated as below 0.01 millimeter in diameter. In case the mineral matter is decomposed by the necessary heat, the ignition must be omitted, and an approximate equivalent can be obtained by multiplying the albuminoid ammonia of the sample by 50.[52] In this case it is necessary to deduct an equivalent amount from the other fine portions, as otherwise the analyses when expressed in percentages would add up to more than one hundred.

Five grams of the ignited fine particles are put in a beaker 90 millimeters high and holding about 230 cubic centimeters. The beaker is then nearly filled with distilled water at a temperature of 20° C., and thoroughly mixed by blowing into it air through a glass tube. A larger quantity of sand than 5 grams will not settle uniformly in the quantity of water given, but less can be used if desired. The rapidity of settlement depends upon the temperature of the water, so that it is quite important that no material variation in temperature should occur. The mixed sand and water is allowed to stand for fifteen seconds, when most of the supernatant liquid, carrying with it the greater part of the particles less than 0.08 millimeter, is rapidly decanted into a suitable vessel, and the remaining sand is again mixed with an equal amount of fresh water, which is again poured off after fifteen seconds, carrying with it most of the remaining fine particles. This process is once more repeated, after which the remaining sand is allowed to drain, and is then dried and weighed, and calculated as above 0.08 millimeter in diameter. The finer decanted sand will have sufficiently settled in a few minutes, and the coarser parts at the bottom are washed back into the beaker and treated with water exactly as before, except that one minute interval is now allowed for settling. The sand remaining is calculated as above 0.04 millimeter, and the portion below 0.04 is estimated by difference, as its direct determination is very tedious, and no more accurate than the estimation by difference when sufficient care is used.

Determination of the Sizes of the Sand-grains.—The sizes of the sand-grains can be determined in either of two ways—from the weight of the particles or from micrometer measurements. For convenience the size of each particle is considered to be the diameter of a sphere of equal volume. When the weight and specific gravity of a particle are known, the diameter can be readily calculated. The volume of a sphere is 1⁄6πd3, and is also equal to the weight divided by the specific gravity. With the Lawrence materials the specific gravity is uniformly 2.65 within very narrow limits, and we have w⁄2.65 = 1⁄6πd3. Solving for d we obtain the formula d = .9∛w, where d is the diameter of a particle in millimeters and w its weight in milligrams. As the average weight of particles, when not too small, can be determinedd with precision, this method is very accurate, and altogether the most satisfactory for particles above 0.10 millimeter; that is, for all sieve separations. For the finer particles the method is inapplicable, on account of the vast number of particles to be counted in the smallest portion which can be accurately weighed, and in these cases the sizes are determined by micrometer measurements. As the sand-grains are not spherical or even regular in shape, considerable care is required to ascertain the true mean diameter. The most accurate method is to measure the long diameter and the middle diameter at right angles to it, as seen by a microscope. The short diameter is obtained by a micrometer screw, focussing first upon the glass upon which the particle rests and then upon the highest point to be found. The mean diameter is then the cube root of the product of the three observed diameters. The middle diameter is usually about equal to the mean diameter, and can generally be used for it, avoiding the troublesome measurement of the short diameters.

The sizes of the separations of the sieves are always determined from the very last sand which passes through in the course of an analysis, and the results so obtained are quite accurate. With the elutriations average samples are inspected, and estimates made of the range in size of particles in each portion. Some stray particles both above and below the normal sizes are usually present, and even with the greatest care the result is only an approximation to the truth; still, a series of results made in strictly the same way should be thoroughly satisfactory, notwithstanding possible moderate errors in the absolute sizes.

Calculation of Results.—When a material has been separated into portions, each of which is accurately weighed, and the range in the sizes of grains in each portion determined, the weight of the particles finer than each size of separation can be calculated, and with enough properly selected separations the results can be plotted in the form of a diagram, and measurements of the curve taken for intermediate points with a fair degree of accuracy. This curve of results may be drawn upon a uniform scale, using the actual figures of sizes and of per cents by weight, or the logarithms of the figures may be used in one or both directions. The method of plotting is not of vital importance, and the method for any set of materials which gives the most easily and accurately drawn curves is to be preferred. In the diagram published in the Report of the Mass. State Board of Health for 1891, page 430, the logarithmic scale was used in one direction, but in many instances the logarithmic scale can be used to advantage in both directions. With this method it has been found that the curve is often almost a straight line through the lower and most important section, and very accurate results are obtained even with a smaller number of separations.

Examples of Calculation of Results.—Following are examples of representative analyses, showing the method of calculation used with the different methods of separation employed with various materials.

I. ANALYSIS OF A GRAVEL BY HAND-PICKING, 11,870 GRAMS TAKEN FOR ANALYSIS.

Number of Stones
in Portion.
(Largest
Selected
Stones.)		Total
Weight of
Portion.
Grams.		Average
Weight of
Stones.
Milligrams.		Estimated
Weight of
Smallest
Stones
Milligrams.		Corresponding
Size.
Millimeters.		Total
Weight of
Stones
Smaller than
this Size.		Per Cent of
Total
Weight
Smaller than
this Size.
................11,870100
103,320332,000250,000568,55072
101,930193,000165,000496,62056
101,380138,000124,000455,24044
202,200110,00093,000413,04026
201,52076,00064,000361,52013
201,00050,00036,000305204.4
2046023,00010,0002060.5
10404,0002,0001120.2
Dust20....................

The weight of the smallest stones in a portion given in the fourth column is estimated in general as about half-way between the average weight of all the stones in that portion and the average weight of the stones in the next finer portion.

The final results are shown by the figures in full-faced type in the last and third from the last columns. By plotting these figures we find that 10 per cent of the stones are less than 35 millimeters in diameter, and 60 per cent are less than 51 millimeters. The “uniformity coefficient,” as described below, is the ratios of these numbers, or 1.46, while the “effective size” is 35 millimeters.

II. ANALYSIS OF A SAND BY MEANS OF SIEVES.

A portion of the sample was dried in a porcelain dish in an air-bath. Weight dry, 110.9 grams. It was put into a series of sieves in a mechanical shaker, and given one hundred turns (equal to about seven hundred single shakes). The sieves were then taken apart, and the portion passing the finest sieve weighed. After noting the weight, the sand remaining on the finest sieve, but passing all the coarser sieves, was added to the first and again weighed, this process being repeated until all the sample was upon the scale, weighing 110.7 grams, showing a loss by handling of only 0.2 gram. The figures were as follows:

Sieve
Marked.		Size of
Separation
of this
Sieve.
Millimeters.		Quantity
of Sand
Passing.
Grams.		Per Cent
of
Total
Weight.
190.105.5 .5
140.1351.3 1.2
100.1824.1 3.7
60.32023.2 21.0
40.46 56.7 51.2
20.93 89.1 80.5
102.04 104.6 94.3
63.90 110.7100.0

Plotting the figures in heavy-faced type, we find from the curve that 10 and 60 per cent respectively are finer than .25 and .62 millimeter, and we have for effective size, as described above, .25, and for uniformity coefficient 2.5.

III. ANALYSIS OF A FINE MATERIAL WITH ELUTRIATION.

The entire sample, 74 grams, was taken for analysis. The sieves used were not the same as those in the previous analysis, and instead of mixing the various portions on the scale they were separately weighed. The siftings were as follows:

Remaining on sieve marked 10, above 2.2 millimeters 1.5 grams
Remaining on sieve marked 20, above .98 millimeters 7.0 grams
Remaining on sieve marked 40, above .46 millimeters 22.0 grams
Remaining on sieve marked 70, above .24 millimeters 20.2 grams
Remaining on sieve marked 140, above .13 millimeters 9.2 grams
Passing sieve140, below .13 millimeters 14.1 grams

The 14.1 grams passing the 140 sieve were thoroughly mixed, and one third, 4.7 grams, taken for analysis. After ignition just below a red heat in a radiator, the weight was diminished by 0.47 gram. The portion above .08 millimeter and between .04 and .08 millimeter, separated as described above, weighed respectively 1.27 and 1.71 grams, and the portion below .04 millimeter was estimated by difference [4.7 - (0.47 + 1.27 + 1.71)] to be 1.25 grams. Multiplying these quantities by 3, we obtain the corresponding quantities for the entire sample, and the calculation of quantities finer than the various sizes can be made as follows:

Size of Grain.Weight.
Grams.		Size of
Largest
Particles.
Millimeters.		Weight of all
the Finer
Particles.
Grams.		Per Cent by
Weight of
all Finer
Particles.
Above 2.20 millimeters 1.50....74.00100
.98-2.20 millimeters 7.002.2072.50 98
.46- .98 millimeters22.00 .9865.50 89
.24- .46 millimeters20.20 .4643.50 60
.13- .24 millimeters 9.20 .2423.30 32
.08- .13 millimeters 3.81 .1314.10 19
.04- .08 millimeters 5.13 .0810.29 14
.01- .04 millimeters 3.75 .04 5.16 7
Loss on ignition (assumed to be less than .01 millimeter) 1.41 .01 1.41 1.9

By plotting the heavy-faced figures we find that 10 and 60 per cent are respectively finer than .055 and .46 millimeter, and we have effective size .055 millimeter and uniformity coefficient 8.

The effective size and uniformity coefficient calculated in this way have proved to be most useful in various calculations, particularly in estimating the friction between the sands and gravels and water. The remainder of the article in the Report of the Mass. State Board of Health is devoted to a discussion of these relations which were mentioned in Chapter III of this volume.

APPENDIX IV.
FILTER STATISTICS.

STATISTICS OF OPERATION OF SAND FILTERS.
Place.Year Ending.Total
Quantity
of Water
filtered
for
One Year.
Million
Gallons.		Million
Gallons
Daily.		Area
of
Filters
in use,

Acres.		Average
Daily
Yield,

Million
Gallons
per Acre.		Area of
Filter
Surface
cleaned
in One
Year,

Acres.		Period,
Million
Gallons
per Acre
filtered
between
Scrapings.

Altona

March,18951,6204.443.081.4531.052
March,18961,7304.753.081.5548.536
March,18971,9605.403.081.7544.045
March,18981,9405.303.081.7236.553

Amsterdam, River

Dec.,18941,3903.805.430.712362
Dec.,18961,4904.085.430.754831
Dec.,18971,6004.405.430.813053

Amsterdam, Dunes

Dec.,18942,3306.404.941.2911620
Dec.,18962,3606.504.751.379026
Dec.,18972,2906.254.751.3110921

Ashland, Wis

Feb.,18973981.090.502.184.8383

Berlin, total

Mar.,189613,00035.6025.101.42
Mar.,189712,90035.4025.101.40
Mar.,189813,20036.2027.001.34

Bremen

Mar.,18951,1903.272.511.315024
Mar.,18961,2203.343.211.0432.538
Mar.,18971,2803.503.211.0925.250
Mar.,18981,4004.103.211.2834.041

Breslau

Mar.,18952,8407.805.121.524564
Mar.,18962,9608.105.121.5840.074
Mar.,18972,9908.205.121.603781
Mar.,18983,0608.405.121.644371

Brunn

Dec.,18961,1103.041.621.878.6128
Dec.,18971,1903.251.622.009.1131

Brunswick

Mar.,18958152.231.481.5114.855
Mar.,18968402.301.481.5613.363
Mar.,18978202.251.481.5213.760
Mar.,18988702.381.481.6111.973

Budapest

Dec.,18927,36020.203.006.7025429

Copenhagen

Dec.,18952,3306.402.882.224552
Dec.,18962,4906.802.882.355248
Dec.,18972,5807.102.882.475448

Dordrecht

Dec.,18943651.000.561.79

Frankfort on Oder

Dec.,18953100.850.372.282.9107
Dec.,18963250.890.372.407.444
Dec.,18973560.980.372.658.841

Hamburg

Dec.,189411,45031.4034.00.9235033
Dec.,189511,70032.1034.00.9427543
Dec.,189611,50031.7034.00.9326643
Dec.,189712,00032.7034.00.9628542
Dec.,189811,90032.6043.00.7624648

Hudson, N. Y.

Dec.,18926971.910.742.58
Dec.,18935431.490.742.01
Dec.,18955351.460.741.98

Ilion, N. Y.

Feb.,18991820.500.143.571.40130

Königsberg

Mar.,18951,0602.902.701.0738.527
Mar.,18961,0852.972.701.1035.031
Mar.,18971,0852.972.701.1041.027
Mar.,18981,1403.122.701.1644.026

Lawrence

Dec.,18941,0502.882.501.1510105
Dec.,18951,0973.002.501.202741
Dec.,18961,1013.022.501.203037
Dec.,18971,1143.062.501.224127

Liverpool

Dec.,18968,52023.4010.922.1415854

[53]London, all filtersbut not includingground water

Dec.,189265,783180109.751.64 90
Dec.,1893 195116.001.68
Dec.,189468,700188117.001.60
Dec.,189576,900210123.751.70
Dec.,189672,482198123.751.60
Dec.,189773,340201125.001.61

London, Chelsea

Dec.,18975,37014.708.001.85

E. London

Dec.,189718,00049.0031.001.58

Grand Junction

Dec.,18978,56023.4021.751.07

Lambeth

Dec.,189710,37028.4012.252.30

New River

Dec.,189715,75043.0016.502.60

Southwark & Vauxhall

Dec.,189714,80040.5020.501.98

West Middlesex

Dec.,18978,91024.3015.001.61

Lübeck

Mar.,18951,5204.151.402.9516.294
Mar.,18961,6004.381.403.1324.466
Mar.,18971,6504.501.403.2227.061
Mar.,18981,7504.801.403.4238.545

Magdeburg

Mar.,189518805.153.761.3747.540
Mar.,189619505.353.761.4265.030
Mar.,189718805.153.761.3759.032
Mar.,189820705.663.761.5063.033

Mt. Vernon, N. Y

Dec.,18954931.351.101.227.368
Dec.,18966081.661.101.519.266
Dec.,18978082.211.102.0016.649
Dec.,18989332.561.102.3418.451

Posen

Mar.,18953050.840.701.2010.330
Mar.,18963460.940.701.3510.433
Mar.,18973250.890.701.2710.132
Mar.,18983600.990.701.429.638

Poughkeepsie

Dec.,18926961.910.682.8114.050
Dec.,18936671.830.682.7012.056
Dec.,18946331.730.682.551445
Dec.,18956861.880.682.771449
Dec.,18966641.820.682.68973
Dec.,18976151.691.361.24
Dec.,18986111.671.361.2310.8857

Rostock

June,18975601.541.111.389.360
June,18986251.711.111.559.070

Rotterdam

Dec.,1893485013.306.302.11

Stettin

Mar.,189511303.102.261.3726.543
Mar.,189610302.832.261.2515.566
Mar.,18979802.702.261.1916.161
Mar.,189810202.802.261.2420.350

Stockholm

Dec.,189523756.502.782.3370.034
Dec.,189625006.852.782.4568.037
Dec.,189727507.503.602.0876.036

Stralsund

Mar.,18972150.591.110.5316.013
Mar.,18982100.581.110.5117.312

Stuttgart

Mar.,189510402.851.461.9613.776
Mar.,189612203.341.662.0417.769
Mar.,189712703.482.321.5018.768
Mar.,189813203.602.321.5420.265

Utrecht

Dec.,18965101.400.602.333116

Zürich

Dec.,189120105.500.846.508250
Dec.,189221505.900.847.0010215
Dec.,189323106.381.195.3513177
Dec.,189422506.151.195.1817133
Dec.,189524606.701.195.622791
Dec.,189623606.451.663.883079
Dec.,189725006.841.664.133571
Dec.,189827307.501.664.504758
PARTIAL LIST OF CITIES USING SAND FILTERS.
Place.When
Built.		Population.
1890.		Area
of
Filters.		Number
of
Filters.		Average
Daily
Consumption.
UNITED STATES.
Poughkeepsie. N. Y.187224,0001.3631.67
Hudson, N. Y.18749,9700.7421.50
St. Johnsbury, Vt.187(?)3,8570.1430.70
Nantucket, Mass.18933,2680.1110.09
Lawrence, Mass.189344,6542.5013.00
Ilion, N. Y.18934,0570.1420.50
Mount Vernon, N. Y.189410,8301.1031.66
Grand Forks, N. D.18944,9790.421....
Milford, Mass.18959,9560.2510.70
Ashland, Wis.18959,9560.5031.09
Hamilton, N. Y.18951,7440.1210.03
Lambertville, N. J.18964,1420.2820.25
Far Rockaway, N. Y.18962,2880.9220.93
Red Bank, N. J.18975000.0320.10
Somersworth, N. H.18976,2070.501....
Little Falls, N. Y.18988,7830.761....
Berwyn, Penna.18988260.523....
Harrisburg, Penna.18991,2000.1220.15
Albany, N. Y.189994,9235.60811.00[54]
Rock Island, Illinois189913,6341.2033.50
Total....259,77417.314526.87
BRITISH COLUMBIA.
Victoria....16,8410.8231.80
SOUTH AMERICA.
Buenos Ayres....500,0004.153....
Montevidio........Filtersreported....
HOLLAND.
Amsterdam....555,82110.181211.20
Rotterdam....290,0006.301813.00
The Hague....191,0002.8864.20
Schiedam....25,3001.3350.68
Utrecht....140,0000.60....1.40
Groningen....57,9000.592....
Dordrecht....34,1000.5621.00
Leeuwarden....30,7000.312....
Vlaardingen....................
Sliedrecht....................
Gorinchem....10,000............
Zutphen....18,000............
Leyden....44,200............
Enschede....................
Middelburg....17,000............
Total....1,414,02122.754731.48
GREAT BRITAIN.
London....5,030,267125.00120200.00
Liverpool....790,00010.92....26.67
Dublin....349,0005.001018.00
Leeds....420,0006.00817.99
Bradford....436,2604.62613.31
Leicester....220,0052.50....4.75
York....72,0832.0463.00
Edinburgh....292,3642.00418.00
Darlington....43,0001.327....
Wakefield....36,8151.25........
Carlisle....40,0000.90........
Dumfries....17,8210.25........
Accrington....42,000............
Birmingham....680,140........19.05
Blackburn....130,000........4.10
Bolton....250,000........6.60
Chester....40,000............
Halifax....217,000........5.18
Hereford....20,000............
Middlesborough....187,331........11.39
Newcastle....320,000........14.00
Oldham....145,800........5.30
Oxford....53,000........1.59
Preston....113,864........4.20
Reading....71,558........3.00
Southampton....76,430........3.45
Wigan....60,000........1.22
Worcester....45,000........1.93
Total....10,199,738161.80161382.73
GERMANY.
Hamburg....661,20042.002233.00
Berlin....1,746,42431.455536.00
Breslau....380,0005.1258.20
Magdeburg....217,0673.76115.66
Bremen....157,5003.21123.50
Altona....162,4273.08135.40
Königsberg....176,0002.7073.00
Stuttgart....162,5162.32....4.00
Stettin....145,0002.2693.00
Lübeck....70,0001.4064.50
Brunswick....100,8831.4842.30
Stralsund....30,1051.1160.60
Rostock....49,8911.1131.54
Lignitz....46,8520.9661.40
Posen....75,0000.7040.90
Schwerin....36,0000.6540.50
Chemnitz....164,7430.593....
Worms....30,0000.5030.64
Ratibor....20,7290.423....
Frankfort on Oder....59,1610.3750.89
Kiel....69,2140.31....1.50
Tilsit....30,0000.25....0.20
Brieg....20,1540.204....
Gluckstadt....6,2140.14....0.10
Wandsbeck....22,0000.13....0.30
Total....4,639,080106.22185117.13
OTHER EUROPEAN FILTERS.
Warsaw....500,0006.20126.00
St. Petersburg....954,0005.851139.00
Odessa....380,0004.7558.00
Choisy le Roi and....}200,000{3.852510.00
Neuilly sur Marne....2.3115....
Copenhagen....340,0002.8896.80
Stockholm....274,0002.78....7.00
Antwerp....240,0002.1082.00
Zürich....96,8391.66....7.00
Brunn........1.62....3.04
Constantinople, South side........0.743....
Total....2,984,83934.748888.84
ASIA.
Blandarwada, India........1.976....
Agra, India........1.37........
Bombay, India....821,0001.224....
Shanghai, China........0.884....
Hong Kong........0.676....
Yokohama, Japan....110,0000.583....
Calcutta, India....466,000............
Tokyo, Japan....................
Baroda, India....................
Allahabad, India....................
Total....1,397,0006.6923
SUMMARY.
United States....259,77417.314526.87
British Columbia....16,8410.8231.80
South America....500,0004.153....
Holland....1,414,02122.754731.48
Great Britain....10,199,738161.80161382.73
Germany....4,639,080106.22185117.13
Other European countries....2,984,83934.748888.84
Asia....1,397,0006.6923....
Total....21,411,293354.48555648.85
LIST OF CITIES AND TOWNS USING MECHANICAL FILTERS.
ARRANGED BY POPULATIONS.

Abbreviations.--P., Pressure filters; G., Gravity filters; J., Jewell system; N. Y., New York system;W., Warren system; C., Continental system; Am., American system.

Place.Population,
1890.		Filters
First
Installed.		Nominal
Capacity
of Filters,
1899.
Million
Gallons.		Average
Consumption,
Million
Gallons:
Water Works
Manual.		Area of
Filters,
Sq. Ft.,
1899.		Filter
System.
Denver, Col.108,204 2260Special.
Atlanta, Ga.65,533188784.542056N. Y. P.
St. Joseph, Mo.52,324189810.2 3842J. G.
Oakland, Cal.48,68218915101960N. Y. P.
Kansas City, Kan.38,3161898622260J. G.
Wilkesbarre, Pa.[55]37,718 10 3166J. G.
Norfolk, Va.34,871189963.52112J. G.
Augusta, Ga.33,300189963.82112N. Y. G.
Quincy. Ill.30,494189241.21582J. G.
Dubuque, Iowa[56]30,31118992 880J. G.
Terre Haute, Ind.30,217189043{1076
226		N. Y. P.
J. G.
Elmira, N. Y.29,7081897632034J. G.
Chattanooga, Tenn.29,10018879 2080J. & N. Y. P.
Davenport, Iowa26,87218917.532380Am. P.
Little Rock, Ark.25,87418915.5 1544Am., J., & N. Y. P.
Winnipeg, Mann.25,64218871.5390N. Y.P.
Oshkosh, Wis.22,83618912.42.1550W. G.
Macon, Ga.22,746189341.651437J., W., & N. Y.
Burlington, Ia.22,56518943.5 1243J. G.
Knoxville, Tenn.22,535189451.931404W. G.
Lexington, Ky.21,567189521.2678J. G.
Kingston, N. Y.21,261189741.51120N. Y. P.
York, Penna.20,793189942.371408J. G.
Biddeford, Maine20,500189632780W. G.
Newport, R. I.19,467 42.1 Special.
Bangor, Maine19,1031897531404W. G.
Cedar Rapids, Ia.18,02018962.52905J. G.
Elgin, Ill.17,82318884.31780Am. P.
Decatur, Ill.16,8411893321008W. G.
Belleville, Ill.15,361 10.6339J. G.
Columbia, S. C.15,35318923 678J. G.
Keokuk, Ia.14,10118933 980N. Y. P.
Ottumwa, Ia.14,001189521.2678J. G.
Rock Island, Ill.[55]13,634 23.5452J. G.
Raleigh, N. C.12,678188711296N. Y. P.
Shreveport, La.11,97918891 312N. Y. P.
New Castle, Penna11,6001898421408N. Y. G.
Charlotte, N. C.11,557189610.5530N. Y. G.
Nebraska City, Neb.11,49418910.40.7116N. Y. P.
Streator, Ill.11,414 21.3100Western & Am. P.
Hornelsville, N. Y.[56]10,96618993 700N. Y. P.
Augusta, Maine10,52718870.61.6100W.
St. Thomas, Ont.10,37018912.50.6700N. Y. P.
Cairo, Ill.10,32418890.82.5197N. Y. P.
Alton, Ill.10,2941898311056N. Y. G.
Asheville, N. C.10,235188910.35312N. Y. P.
Greenwich, Conn.10,131188720.4592N. Y. P.
Huntington, W. Va.10,10818992 704N. Y. G.
Beaver Falls, Pa.9,735 24.5 N. Y.
Champaign, Ill.[55]9,719 0.75 N. Y.
Chatham, Ont.9,052189510.4280N. Y. P.
Adrian, Mich.8,75618991.750.45565J. G.
Athens, Ga.8,639189310.45420W. G.
East Providence, R. I.8,42218990.5 176J. G.
Winston, N. C.8,01818950.50.3156W. G.
Danville, Penna.7,998189611226J. G.
Clarksville, Tenn.[56]7,92418991.50.5704J. G.
Stevens Point, Wis.7,89618890.50.25156N. Y. P.
Carlisle, Pa.7,62018961.5 339J. G.
Calais, Me.7,29018931.50.85275W. G.
Long Branch, N. J.7,231188831.3904N. Y. P.
Creston, Ia.7,20018910.50.3150J.
St. Hyacinthe, Que.7,016189810.84294J. P.
Rome, Ga.[56]6,95718991.51.3528J. G.
Westerly, R. I.6,81318961.50.375396N. Y. G.
Merrill, Wis.6,80918971 339J. G.
Dennison, Ohio[56]6,76718991.251528J. G.
Parsons, Kan.6,736189420.6452J. G.
Waterloo, Iowa6,67418911.50.7565J. G.
Somerville, N. J.6,41718851.90.75552N. Y. P.
Athol, Mass.6,31918881.50.5350N. Y. P.
Owego, N. Y.6,200188710.75234N. Y. P.
Brunswick, Maine6,01218870.60.33100W.
Bucyrus, Ohio5,97418870.50.55156N. Y. P.
Warren, Ohio5,97318961.51.5462W. G.
Hopkinsville, Ky.5,83318950.50.15140N. Y. P.
Brainerd, Minn.5,70318970.5 156N. Y. P.
New Brighton, Pa.5,61618890.5 156N. Y. P.
Niagara Falls, N. Y.5,50218964.52.621019J. G.
Durham, N. C.548518930.90.7252W. G.
Winfield, Kan.518418941 336W. G.
Louisiana, Mo.509018880.8 242N. Y. P. & G.
Trenton, Mo.503918890.4 128N. Y. P.
Lorain, Ohio4863189631.51356J. G.
Sidney, Ohio[55]4850 0.5 N. Y.
Mexico, Mo.478918890.30.466N. Y. P.
Mt. Clemens, Mich.4748188810.6251N. Y. P.
Riverside, Cal.468318920.09 20N. Y. P.
Columbus, Miss.[56]455918990.50.175176J. G.
Winchester, Ky.451918940.750.107152J. P.
Salisbury, N. C.441818890.50.35156N. Y. P.
Eufaula, Ala.439418970.5 140N. Y. P.
Greenville, Tex.433018880.80.175156N. Y. P.
Exeter, N. H.428418870.1140.17934N. Y. P.
Bordentown, N. J.423218900.50.5156N. Y. P.
Lake Forest, Ill.420318921 168J. P.
Henderson, N. C.419118990.25 118W. G.
Reading, Mass.4088189610.198336W. G.
Goldsboro, N. C.401718960.50.1156W. G.
Rich Hill, Mo.400818930.50.24140N. Y. P.
Mt. Pleasant, Ia.399718880.5 156N. Y. P.
Murphysboro, Ill.388018900.2 60N. Y. P.
Brandon, Manitoba3778189310.36240N. Y. P.
Danville, Ky.376618940.50.1140N. Y. P.
Royersford, Pa.3612189310.08226J. G.
Warsaw, Ind.351418960.50.5156N. Y. P.
Ashbury Park, N. J.3500 20.5670C.
Keyport, N. J.341118950.50.06156W. G.
Deseronto, Ont.333818960.50.84147J. P.
Milledgeville, Ga.332218930.5 156N. Y. P.
Carlinville, Ill.3293 0.1 38Am. or Jackson.
Gettysburg, Pa.322118940.30.07578W. G.
Independence, Kan.312718910.750.25129Am. P.
LaGrange, Ga.309018930.25 34N. Y. P.
Paola, Kan.294318870.250.4566N. Y. P.
Benwood, W. Va.[56]293418991 306J. G.
Gadsden, Ala.290118871.325 430N. Y. P. & G.
Lamar, Mo.286018910.25 78N. Y. P.
Longueuil, Que.275718950.40.3100N. Y. P.
Washington, Mo.272518880.20.07550N. Y. P.
Renfrew, Ont.261118970.432 100N. Y. P.
Oswego, Kan.257418930.50.3140N. Y. P.
Holden, Mo.252018930.20.05100N. Y. P.
Burlington, Kan.2239 0.5 79J.
Council Grove, Kan.221118980.50.0878N. Y.
Wakefield, R. I.[56]2170 0.150.25 N. Y.
Catonsville, Md.211518900.25 78N. Y. P.
Attica, N. Y.199418960.4 100N. Y. P.
Hightstown, N. J.187518990.250.02578N. Y. G.
No. Berwick, Me.180318960.3 78W. G.
Dunnville, Ont.177618990.5 140N. Y. P.
Rogers Park, Ill.170818890.40.35100N. Y. P.
Eatonton, Ga.168218970.5 132N. Y. G.
Caldwell, Kan.164218900.5 156N. Y. P.
LaGrange, Tex.162618910.25 34N. Y. P.
Richfield Springs, N. Y.162318890.35 100N. Y. P.
Valatie, N. Y.143718940.15 50N. Y.
Tunkhannock, Pa.1253 0.1 N. Y.
Mechanics Falls, Me.103018980.72 176W. G.
New Bethlehem, Pa.102618990.1 50J. G.
Fairmount, W. Va.102318981 280N. Y. P.
Atlantic Highlands, N. J.945 0.30.109130C.
Rumford Falls, Me.89818970.5 113W. G.
Lakewood, N. J.73018890.5 156N. Y. P.
Veazie, Me.650188910.1176W. G.
Portersville, Cal.60618900.1510.06034N. Y. P.
Holmesburg, Pa. 189610.046280N. Y. P.
Pickering Creek, Pa. 18960.75 234W. G.
Overbrook, Penna. 18950.25 78W. G.
Vandergrift, Pa. 18970.5 156W. G.
Frazerville, P. Q.[56] 18990.2 78N. Y. G.
Arnate, Pa. 18990.12 50N. Y. G.
Chihuahua, Mex.[56] 18991 612J. G.
West Reading, Pa. 0.07 W. G.
Totals1,565,881 25210877,806

Special filters, neither sand nor mechanical: Wilmington, Del.; Pop., 61,431; area, 10,000 sq. ft.; nominal capacity, 10 million gallons. See Eng. News, Vol. 40, p. 146.