The Broadening Science of Sanitation

I

BACTERIOLOGY, child of Louis Pasteur, basis of aseptic surgery and preventive medicine, has become wellknown to the educated world during the past thirty years. The words ‘ germ ’ and ‘microbe’ do not impress us with awe and dread as they once did, for we realize that the kingdom of the bacteria is gradually being subjugated by man. We see this in changing medical practice, we see it in popular advertisements and in many other ways; but, surest of all, we sec it in the steadily diminishing death-rates from communicable diseases as revealed by vital statistics the world over. Certain it is that one of the greatest events of the dawning twentieth century is the triumph of man over his microscopic foes.

While we contemplate this result with satisfaction we are apt to forget the many activities which are working together to bring it about. It is well to pause from time to time and consider what is being done, so that our ideas may be readjusted to the new methods which are continually being put into practice.

The world has so long entrusted the care of its health to doctors of medicine, skilled in the arts of healing, that we call these various protective agencies against disease by the general term ‘preventive medicine,’ forgetting for the moment that a large part of this work is not medical at all. Much of it, in fact, is something quite different, and is better described by the term sanitary engineering, or by the broader word, sanitation. Even the term sanitary engineer has been misused, or at least has been used in a too limited sense. So many aspiring plumbers have styled themselves sanitary engineers that the title bids fair to become synonymous with ‘the drain man.’

Broadly defined, sanitation covers all the arts which make for clean environment, and sanitary engineers concern themselves not alone with drains and sewers and sewage-treatment works, but with all of the many activities required to provide communities with pure water, fresh air, clean food, and, in general, clean surroundings. A task so vast naturally calls to its aid many sciences. These must be culled and the selected parts interwoven to form a new science, the science of public health. It is in response to this new demand of civilization that chairs of sanitary engineering are being founded in our universities, and that students who are being trained to become health officers are taught some parts of the arts of engineering as well as some parts of the arts of medicine.

A few years ago, sanitarians were assiduously cultivating newly discovered germs; now, they are also studying flies and mosquitoes and rats and squirrels and other insects and animals which may harbor and spread these germs. A few years ago, they were minutely analyzing samples of water; now they are also studying the currents in lakes and the laws of sedimentation and filtration. Until quite recently, placards were used to warn people away from houses of pestilence, while the active cause was still at large; now, carefully kept vital statistics are used as the basis of epidemiological detective work, which rivals in brilliancy that of Sherlock Holmes himself. Thus the sanitarian must study not micrology alone, but entomology and limnology and demography, and other sciences, the very names of which still have an unfamiliar sound. Truly the science of sanitation is broadening. Health officers are becoming biological engineers.

II

Learning and unlearning go together. The discovery of each new fact explodes some old theory. Some one, whose name I do not now recall, has said, ‘It is better not to know so much than to know so many things that ain’t so.’ Nowhere is this better illustrated than in the sanitation of the air.

Let us take for example, sewer-gas, the old bugaboo that frightened our fathers. After complicating our plumbing systems with traps and more traps and vents and back-air pipes, we find at last that the air of sewers does not cause disease, as we were taught, or, if it does so at all, that the chance of its causing disease is so small as to be almost negligible. Miquel found that the air of the Paris sewers contained fewer bacteria than the air over the Paris streets; long experience has shown that the workmen in sewers do not contract the diseases that one might expect them to contract: Winslow has calculated that a person breathing air all night from a house drain would inhale fewer bacteria of intestinal origin than he would swallow with a glass of Croton water from a tap in New York City.

This idea certainly seems revolutionary, and we must be careful not to go to the other extreme. It would not do to do away with all traps and similar fixtures intended to prevent the air of the sewers from entering our houses. Sanitation ought to make for our comfort as well as for our health, and bacterial infection is not all there is to the causation of disease. Besides, it is just possible that our latest discoveries are not without flaw. Nevertheless, considering all of the facts in their quantitative aspect, it does seem that a good case has been made against the unnecessary complexity of our house plumbing systems, and it would appear to be wise economy to simplify their design and improve the quality of t he materials and the workmanship. Already in England a Royal Commission, after making an extensive investigation, has recommended that the trap on the main drain from the house to the sewer be no longer required. In Germany these traps have never been much used.

Sanitarians have gone even further than to overthrow the sewer-gas theory of disease. They have found that very few cases of sickness are ever caused by infection passing through the air. The aerial transmission of disease germs from patient to victim is not denied, but it has been found to be a very small factor, indeed almost a negligible factor, except in the case of a few diseases where the virus is ultramicroscopic. Acting on this theory, health officers little by little have been abandoning the practice of fumigating and disinfecting rooms which have been occupied by persons sick with contagious diseases. In hospitals, segregation of different contagious diseases in separate rooms is no longer deemed absolutely necessary. Cases of scarlet fever, measles, and typhoid fever have been kept in the same ward, with an extremely small proportion of cases of cross-infection. Practice has confirmed the theory in various ways, and the aerial transmission of disease has been relegated to a subordinate position.

But aerial transmission has been replaced by something else, the theory of contact. The germs do not float in the air from one person to another, but are carried on solid objects, — on spoons and knives and forks, on soiled clothing, on pencils and toys, books and tickets, door-knobs and drinking cups, and on scores of objects which pass from hand to hand or from hand to mouth. In surgery it is not so much infection from the air that is feared as that from unclean instruments and utensils. The safeguard against contact is personal cleanliness and handdisinfection when caring for the sick. It is so simple that people neglect it.

Without wishing to elaborate too much on the theory of contact, which after all is like the long-ago-discarded theory of fomites, limited to a short period of time between the handling of objects by patient and victim, it may not be out of place to suggest that many so-called children’s diseases are diseases of childhood because in childhood there is more opportunity for contact. Many objects pass back and forth in school and in the course of natural play. A knowledge, by the mother, of the theory of contact, accompanied by judicious restraint in these little things, may prevent many a case of measles, or scarlet fever, yes, and many a ‘cold,’ from being contracted by the child.

III

If we consider another phase of the air-problem, namely, ventilation, we find that here all is being changed. Old ideas are being flung to the winds, and new theories are struggling for position. To some the situation appears chaotic, but, little by little, facts are being gathered and put together; and those best qualified to judge believe that it will not be long before ventilation will stand forth as a new art based upon sound scientific principles. The trouble in the past has been that reliance was placed upon half truths.

For many years, ventilation standards were based chiefly on one element of the problem, that is, on carbonic acid. It was known that human beings inhale oxygen and exhale carbonic acid, and that when people remained for some time in a tightly closed room, the oxygen content of the air decreased slightly while the amount of carbonic acid slightly increased. As it was a matter of experience that these changes were attended by feelings of depression and general physical discomfort on the part of the occupants, the argument. was naturally made that the cause, of this malaise was the increase in the carbonic acid and the decrease in oxygen.

Modern researches have shown that this reasoning was of the order of post hoc ergo propter hoc. Several things had been left out of account. One of these was heat, closely allied with which is moisture, or humidity. Another was air-movement. And another was aircleanliness. Each of these deserves attention, for taken together they form the basis of the modern conception of ventilation requirements. We might sum up the new ideas in a single phrase and say that for indoor comfort we need clean air in gentle motion, and with its temperature and humidity adjusted to the ordinary exercise of the occupants.

The reason for the elimination of carbonic acid and oxygen ratios is that physiologists have found that the human body possesses powers of automatic readjustments to slight changes in these gases. In most localities the barometric pressure is continually fluctuating, and the amount of oxygen in a given volume of air varies accordingly. Unless the change is great or sudden these fluctuations do not seem to affect one’s health or comfort. Extreme conditions, we all know, have an important influence on the body. Thus, at the top of Pike’s Peak, with low atmospheric pressure, one may have mountain sickness, while laborers working in the compressed air of a caisson are subject to the very serious disease known popularly as ‘ the bends.’ These troubles are due more to the rate of change of pressure than to the maintenance of continued high or low oxygen content. People soon become accustomed to high altitudes, and laborers do not suffer from the change from high pressure to normal pressure if this change is made gradually. An important element in the caisson disease is thought to be the deposition of bubbles of nitrogen gas within the tissues of the body when the pressure is lowered as one suddenly emerges from a caisson.

The most direct proof that slight increases in carbonic acid and reductions of oxygen do not produce physical discomfort is that derived from the experiments in which persons have been kept by physiologists in close chambers, known as calorimeters. Although remaining there until the concentrations of carbonic acid were far beyond those which occur in crowded rooms and cars, the occupants of these calorimeters experienced no discomfort provided the temperature and humidity were kept, within certain limits and the air was kept in motion. If the temperature and humidity increased, physical discomfort became manifest even though the amount of carbonic acid in the air was low.

To discuss here the complicated heat relations of the body would be too great a task, and moreover this is one of the matters not yet thoroughly investigated. There is reason to believe, however, that much of the discomfort experienced in crowded rooms is due to rise of temperature and humidity and to the effect which this has on the breathing mechanism. Cooling the skin, English physiologists say, affects metabolism and thus in an indirect way stimulates the lungs to secrete more oxygen, which enters the blood, while increase of skin-temperature tends to check this action. The temperature of the skin is influenced by many things: by the amount of heat produced in the body from food-consumption, by the clothing worn, by exercise, by the perspiration formed and evaporated, by the temperature and humidity of the surrounding air, and by air-movement. So much depends upon the occupation of the persons considered, whether exercising or sitting still, that our present data as yet do not permit definite standards of air-temperature and humidity to be established. Temperature and humidity, it will be noticed, are coupled together. This is because they are mutually related. So true is this that many believe that the reading of the wet-bulb thermometer gives a ‘ sentient temperature’ which better expresses its influence on the body.

It is not the air of a room generally but the air near the skin that affects bodily comfort, hence air-motion is a matter of great importance. Sitting in warm still air is uncomfortable because the atmospheric envelope surrounding the body checks evaporation and the skin-temperature rises. In a crowd the air does not move freely between the bodies, while heat and moisture are given off to it. The combined result is to retard the absorption of oxygen by the blood in the lungs and we have the well-known effects of ‘crowd poison.’ Similarly, in an assembly room, the air between the seats becomes nearly motionless and the same result may follow. That air thus stagnates was shown by tests once made in a church, where observers placed in the exhaust-air duct noticed that an odor of perfumery pervaded the outflowing air whenever the congregation arose. The beneficial effect of the use of fans in the cars of the New York Subway was a striking example of the effect of air-motion. We might add also the benefits of sleeping porches, and the out-of-doors treatment for pneumonia. Leonard Hill, a noted London authority on ventilation, lays stress upon the value of a fluctuating atmospheric environment, claiming that variations in temperature and wind-movement stimulate the skin, and that long-continued uniformity produces discomfort.

IV

Cleanliness is an essential quality of indoor air, and one of the faults of the past has been the failure to give this matter due consideration. Air inlets have been placed with gross disregard of the amount of dirt likely to be drawn in. They have usually been placed near the ground level and often on dusty streets, where in extreme cases screens over the inlets become clogged with hair and chips and other débris almost daily, the finer dirt passing into the rooms.

Modern cities are dust - producers. Streets and pavements and sidewalks are worn by the friction of the traffic, car-wheels are ground to metallic dust; fabrics turn to lint; fuel burns with products of smoke and ashes. Dust is being continually produced both within and without our houses. Recent studies in several cities have shown that the numbers of dust particles in the air above sidewalks range from one hundred thousand to a million per cubic foot. At higher levels the numbers are less.

At the Woolworth Building, in New York City, the highest building in the world (716 feet), the air at the street level on July 2, 1913, contained 221,000 dust particles per cubic foot; at the tenth story, 85,000; at the thirtieth story, 70,000, and at the fifty-seventh story 27,000. As a figure for comparison, the air over Long Island Sound at a point several miles from shore was found to contain 18,000 dust particles per cubic foot. Dusty air contains bacteria, but their numbers are fewer than those of the dust particles. At the John Hancock Building in Boston on June 5, 1913, the air near the side-walk contained 1330 bacteria and 20 mould-spores per cubic foot; at the tenth story the corresponding numbers were 330 bacteria and 3 mould-spores per cubic foot. The elimination of city dust is a constant and ever-changing problem for the sanitary engineer. The elimination of the horse from city streets is helping to reduce the organic dust, but the automobile is itself a dust-creator when used on road surfaces not adapted to its weight and speed. Asphalt streets do not disintegrate as do macadam streets, but, as they are smoother, the wind more readily moves such dust as is found there.

The smoke problem is a special phase of the problem of air-pollution, so important as almost to stand alone. Especially serious is this in the softcoal region, where the pall of soot cuts off the sunlight, creates fogs, retards vegetation, causes buildings and house furnishings and clothing to deteriorate, increases laundry bills, and in many ways produces discomfort, and presumably lowers human vitality and increases the death-rate. I say presumably, because the vital statistics bearing on this point are not yet sufficient to establish this quantitatively.

Even more important than dust and soot are the poisonous gases resulting from incomplete combustion of coal. City air is sometimes acid with sulphur compounds. The air of our dwelling houses contains more of the poisonous gas, carbonic oxide (not carbonic acid), than is generally realized. The increased use of water-gas during the past twenty years is said to have increased the number of accidental asphyxiations in Massachusetts. The gas-stove is another producer of this poisonous gas, a trouble which can be obviated, however, by taking proper precautions. An interesting experience of carbonic-oxide poisoning is related by Schneider. In a certain house near Boston one after another of the servants and members of the family began to be troubled with hallucinations. They heard unaccountable noises, and ‘saw things,’ and experienced these troubles to such an extent as to demand an investigation. This study showed that they were all suffering from carbonic-oxide poisoning caused by gas leaking from the furnace. One cannot but wonder whether some of the hallucinations of historical record did not result from this cause. How strange if the Salem witchcraft tragedies had such an origin!

Foul odors also are an element in unclean air. Whether physical or psychological in their effect matters not, for ill-smelling rooms are so obviously insanitary that odor plays an important part in ventilation. Change of air is essential in a room occupied by many people.

The practical question now comes, how can we secure clean air and keep it in motion and have it properly warmed or cooled as the case may be. Without attempting to answer a question that has so many answers, I will call attention only to one of the new developments, namely the recirculation of washed air. Dust and bacteria and odors and poisonous gases may be very largely removed from air by washing it, that is, by allowing it to flow horizontally through chambers where water is falling in drops or as a spray. The effect is the same as that of rain. Every one knows how a summer shower ‘freshens’ the air, and cleans it. The water used for washing the air artificially is used over and over until it becomes so foul that it has to be changed. Analyses of the water show that after it has been used in this way it resembles sewage in its impurities.

Air-washers have been used for some years for cleaning outside air, but only recently has it been realized that the process coidd be applied to the air exhausted from a room, and the air made fit to be pumped back into the room and used again. This has been successfully done at Springfield, Massachusetts, in the gymnasium of the College of the Young Men’s Christian Association. The air in the exhaust-duct always had a noticeable odor when the men were exercising on the floor, but after being washed the air was returned with no offensive smell. Examination of the water used for washing the air showed that the odoriferous substances had gone into the water, together with dust particles, bacteria, and even epithelial scales from the skin. If the washer was shut down and the air recirculated the men complained of foul air. Starting the washer restored comfort. The advantage of recirculation lies of course in the saving of heat. When large volumes of air in winter are heated, forced through a building and then outdoors, much heat is wasted. By using a considerable part of the air over and over, heat is saved, and therefore coal and money. It is a proper form of conservation. How far the idea can be put into practice is for the future to determine. That there would be limits to the continued use of the same air is obvious.

V

Water-purification has made wonderful strides since the old sand filter was built at Lawrence, Massachusetts, in 1893. At that time less than half a million people in this country were using filtered water, and many of our largest cities were supplied with water from sources which were grossly polluted. To-day there are very few large cities where the water-supply is not subjected to some kind of artificial purification. Within ten years, filters have been put in operation in Washington, Philadelphia, Pittsburg, Cincinnati, Columbus, New Orleans, Toledo, Minneapolis, Harrisburg, to name some of the more important places, and the total population using filtered water in this country is now upwards of thirteen millions.

Filters are under construction in Baltimore and St. Louis and are likely to be built soon in New York, Cleveland, Chicago, and Milwaukee, and probably also in Boston, where the supply is reasonably safe, but somewhat colored and none too clean. When, a number of years ago, sanitary engineers issued the warning that to use unfiltered surface water was unsafe, it was hardly expected that the country would so quickly respond; but so great has been the reduction in the typhoid fever death-rate in those cities where filters have been introduced, that the amazing thing now is why the remaining cities so long delay.

It has been proved over and over that clean water pays. The reward of filtration is not only in having water safe to drink but in having water so attractive that people will enjoy drinking it and not feel obliged to purchase water from outside sources, — and the boon is greatest to the poorer classes, who cannot afford to buy spring water.

The interesting thing about waterpurification at the present time is the diversity of the processes employed. Filtration, that is the passing of water through layers of sand, is still the dominant feature and is likely to remain so, but many different methods are applied to waters of different original quality to bring them to a condition such that they can be satisfactorily filtered at economical rates. And so many different types of water are met with in the United States that with us the art has become more complicated than it is in Europe.

Settling basins have long been used both in this country and abroad for removing the heavier suspended matter. There is probably no cheaper method. Occasionally, rapid prefiltration through coarse material is used to replace sedimentation. This method is sometimes desirable, but more often, perhaps, is of doubtful expediency. When the original water — commonly known as the raw water — contains large amounts of very finely divided particles of clay, physical methods of preliminary treatment are not sufficient, and coagulation must be brought about by the use of chemicals. Sulphate of alumina, or alum, is most used for this purpose, but sometimes copperas and lime. Where the water is so hard as to need softening it is treated with lime and soda-ash, and recently a new substance called permutit has sprung into use abroad. Swampy waters, stained with peaty matter, also need chemical treatment. Waters containing large amounts of organic matter and lacking in oxygen require aeration, and waters which contain too much carbonic acid require decarbonation. Reservoir waters which contain algæ are treated with copper sulphate, while chloride of lime, liquid chlorine, and, in rare instances, ozone are used as processes supplementary to filtration to destroy any bacteria which may have passed through the filter. The quantity of these chemicals required to sterilize the water is astonishingly small.

These processes are mentioned merely to show how complicated the art has become, and to emphasize the need for men of special training to cope with the manifold problems. The prejudice against the use of chemicals is fast passing away. Why should it not, when a large proportion of the water-supplies of the country is chemically treated without the consumers ever realizing that it is being done?

VI

Not least in importance among recent developments is the discovery of the natural processes of purification which occur in water during storage. Typhoid bacilli do not multiply in water, as once thought, but become gradually ‘devitalized,’ — or, to use plain English, they die, — in a few days or a few weeks, according to the temperature and character of the water. They are able to live longer in cold water than in warm water, hence there are more typhoid epidemics traceable in water in the winter than in the summer, and more in the north than in the south.

Still other causes enhance the safety of stored water, especially in the summer. It has been found that the algæ, the microscopic plants which may be seen floating in the waters of lakes, use up the carbonic acid dissolved in the water and even take carbonic acid away from the dissolved bicarbonate of lime. This leaves the water in a condition in wdiich such bacteria as B. coli typhi are speedily killed. A new interest is thus attached to this class of organisms which heretofore have been regarded chiefly from the standpoint of the bad odors which they produce.

Incidental to this study has arisen a new science which is fast attaining prominence, a science devoted to the study of lakes, their currents, their temperature relations, their dissolved gases, the effect of wind and sunshine and rain, and the mutual effect which all these have on themselves and on the organisms which dwell in the lake, — the science of limnology. A course in limnology is now given at Harvard University.

This study of lakes should prove a pleasant and profitable summer pastime. A lake resembles a living being in many ways. It has a pulse; its surface rises and falls rhythmically. It has a circulation; its waters not only ebb and flow, but there are undercurrents by which the life-giving oxygen is carried to organisms which dwell in its depths. It does muscular work; the shores are eroded and wharves are moved by the ice-pressure. It digests food; and some lakes, sad to say, sometimes have indigestion. And so we might continue the comparison and tell of their smiles and frowns, and the music of their waves upon the shore. Certainly there can be no more fascinating science for the lover of nature than limnology.

VII

Ideas in regard to the disposal of sewage are likewise broadening. New methods of treatment are being devised, and, what is of greater moment, a truer conception of the elements of the problem is beginning to prevail. In this matter popular ideas are many years behind the opinions of the experts. For example, the popular idea is that the problem of protecting water-supplies against infection can be solved by the purification of sewage. This is not true. Let us suppose the case of a river which receives a city’s sewage at some point upstream, and which is used lower down for the watersupply of another city. This is an abhorrent situation. The popular idea is that it is possible to protect the watersupply downstream by purifying the sewage upstream. Sanitary engineers know that with present available methods this cannot be done, and that the safest and most economical way is to filter the water-supply itself, using such auxiliary processes as may be necessary. This does not mean that the upstream city may pollute the river water ad libitum. Far from it. The more polluted a stream is, the higher is the cost of water-filtration and the greater the factor of safety demanded of the water-purification plant, — so that sewage treatment in the case cited may or may not be an element in the problem, according to the size of the stream, the volume of sewage, the proximity of the two places, and other factors which sanitary engineers know how to weigh.

In estimating the danger which may result from untreated sewage the main principle must not be forgotten, namely, that sewage has t he power of causing disease, not because it contains foul-smelling organic matter, nor even because it contains bacteria; but because among the many bacteria present there may be some which have come from persons sick with typhoid fever or dysentery or some such disease, or from persons, known as carriers, who, though not sick, are emitting the germs of these diseases. And the magnitude of the danger is measured by the chance of these pathogenic bacteria getting into other people’s mouths. It is unnecessary to go into details, but everyone to-day knows that there are ways by which minute portions of sewage may thus produce disease, namely, by polluted water, milk, shellfish, by flies, and by contact.

Sewage-disposal has another aspect. Just because sewage-treatment is not the logical way to protect water-supplies we should not consider it useless and unnecessary. Sickness and health are not all there is to life. Our various senses deserve consideration, and offenses to sight and smell should be eliminated as far as possible. Hence streams and lakes and harbors should be kept sufficiently clean to avoid offense, and the degree of cleanliness should be adjusted to the use made of them. Likewise it must not be forgotten that sewage-treatment works in themselves may be a nuisance.

Nor should we fail to utilize the natural powers of self-purification of lakes and streams. To neglect this would be contrary to the modern demand for conservation of natural resources. The ultimate fate of the organic matter in sewage is destruction by oxidation. The oxygen dissolved in the water of lakes and streams may be made to serve this purpose. It does so naturally when crude sewage is discharged into them, but without control the powers of the water may be overtaxed and indigestion may result, as was said before when speaking of lakes.

The cycle of changes in the microscopic life in polluted water is curious and interesting. Studies of the Genesee River, between the mouth of the Rochester sewers and Lake Ontario, made last year, showed that just below the point where the sewage was discharged the water contained large numbers of bacteria; a few miles downstream these decreased and the protozoa increased; next the protozoa decreased and the crustacea increased. The Crustacea serve as food for fish, and fishermen were actually seen at the river mouth catching fish to be taken back to Rochester and used for food. Hence the cycle was complete. This is an excellent illustration of what is ever recurring in nature.

VIII

Other branches of sanitation are likewise developing; older ideas are being replaced by new. In many cases we still speak of them as problems, indicating that the solution is not yet satisfactory. The street-cleaning problem, the garbage and refuse problem, the housing problem, the factory problem, are in the same class with the ventilation problem and the sewage-disposal problem ; and the list might be extended further. Modern science has taught us to do many things. But many things cost many dollars, and cities as well as individuals must cut their garments according to their cloth. Hence the great problem of all sanitary problems is to discriminate between the necessary and the merely advantageous, between the activities which save many lives and those which for the same expenditure save few, between those which make for health and those which make for comfort. Which is more important, a water-filtration plant or works for sewage-treatment? Better housing or more parks? More money for room-disinfection, or a larger corps of district nurses? More plumbing inspectors or better control of the milk-supply? The problem takes different forms in different places.

The solution of these vital problems demands the application of still another science, which is coming to the front, — demography, that is, vital and social statistics. Life-saving is being put on a quantitative basis, and to this end vital bookkeeping is just as much needed as the keeping of monetary accounts. Nowhere is there better opportunity for reform than here. In many of our states practically no records of births and deaths are kept, and in very few states are the records accurate. The Census Bureau is waging a campaign to better these conditions and secure adequate registration laws the country over.

This movement deserves the hearty support of every one. Unless we know the results of the sanitary measures which are put in force, how can we tell how much money it is wise to spend on them? In some cases we do know these results. For example, after the water-filtration plant was put in full operation at Pittsburgh the typhoid fever death-rate in the filtered district fell from 135 per 100,000 to 10; at Philadelphia it fell to 17.5; at Cincinnati, to 9 per 100,000. But how much weight shall be given to the regulation of milk-supplies, how much to motherhood instruction, how much to factory and school inspection, how much to the cleaning of streets and streams? We know only in part, and our sense of perspective in these matters is yet uncultivated. Sanitation to be economical must be put upon a quantitative basis.

If demography is to become a science, and it ought to be so regarded, it will not be sufficient merely to collect and tabulate the facts, and file the reports on dusty shelves. The statistics must be studied and applied. A loose handling of figures must give way to clear thinking and to honest conclusions based on the inviolable laws of logic. Illustrations of the wild and reckless use of so-called statistics are so common that the whole science is sometimes regarded as a house of cards. It is very easy to go astray. The deathrates all over the civilized world have been decreasing during the last generation. Is this the result of improved sanitation? Yes, it is due very largely to that. But, hold! The birth-rates have also been falling; infant mortality rates are high; the fewer the children born, the fewer there will be to die; so that a falling birth-rate may of itself cause the death-rate to drop. Suppose we go further and ask why the birthrate is falling? In part because the age at marriage is increasing among certain classes of society. And why is this? We see that a study of sanitation leads to a study of sociology.

This is an important conclusion. Sanitation cannot be measured in dollars alone, neither can it be measured in terms of births and deaths. It is what lies between one’s birth and one’s death that really counts. Of what avail to add two years to the average length of life if personal comfort and happiness are not also enhanced? To what extent can physical comfort and home life be secured in the tenement-house districts of our cities where people live crowded one thousand to the acre: forty-three square feet of land for each person, — a square seven feet on a side, not much larger than a respectable lot in a cemetery ?

Vital statistics must not be confined to births and deaths. We need to know the effect of environment on the minor illnesses, on the time lost through sickness, on general health, physique, and personal comfort. Do cities yield as strong and healthy men as the country? Does good ventilation add to one’s strength and stature? Does factory sanitation lessen the discomfort and the burden of toil as well as increase the efficiency of the laborers? Such questions as these need to be answered.

Some of the sanitary arts contribute both to longevity and to human enjoyment; others relate to the one or the other. All deserve consideration. The prompt collection and proper disposal of garbage and ashes has but little effect on public health, but foul odors and clouds of dust from collection carts are disagreeable enough. Even sewage treatment is more largely a matter of comfort than of health, although the prompt removal of sewage from an inhabited community is a very important health measure. Not only, however, does water-purification save lives and promote health, but a glass of cool, clean water is a joy in itself.

IX

There is one important, force in the country which has not yet exerted itself as it might, or as it should, in behalf of better sanitation, — the life insurance companies. The mortality records of these companies are of immense value not only to the companies themselves but to the public authorities. Compiled with the acme of statistical skill, and with vast financial resources at command, these records have been applied to a single end, the promotion of life insurance. The data relate chiefly to males of insurable age, but in recent years the records cover a broader field. What is lacking is a proper correlation of the statistics of the life insurance companies with those of sanitary engineering.

Some of the life insurance companies are alive to this opportunity and are already at work, but far more important developments may be expected. Surely the insurance companies realize that it is better to receive premiums from the living than to pay claims to the dead; and just as fire protection in factories has lowered insurance rates, so the safeguarding of life by coöperative sanitation should redound to the benefit of the insured as well as of the insurance companies.

x

Lastly, the broadening science of sanitation calls for broader men, men of sound fundamental education, men of imagination, men of force. The prevention of disease and the promotion of health have passed beyond the boundaries of the medical profession. A new type of health officer is needed; a new career is opening for young men. Typical of the new spirit is the recently established School for Health Officers in Boston, Massachusetts, — a coöperation between Harvard University and the Massachusetts Institute of Technology. It is significant that the administrative board of this new school is composed of a doctor of medicine, a doctor of science, and a civil engineer. As was said before, a health officer is a biological engineer.

The need of reliable men is not confined to the leaders of thought. The shame of American sanitation to-day is neglect of duty, non-enforcement of laws. Legislators do not legislate with wisdom, inspectors do not inspect, attendants do not attend, and laborers do not labor as they should. America is second to none in her engineering conceptions and designs, but America is far behind European nations in the work of operation of all public utilities. This is as true of sewage-treatment works as it is of railroads, as true of the street-cleaning departments as of the police force. No one ever summed up the situation in a more striking phrase than did the late Colonel Waring, the Commissioner of Street Cleaning in New York City, who took as his watchword, ‘A man instead of a voter at the end of the broom. ’

Nor is neglect confined to the official class and to city employees. Individuals are guilty of minor infractions of the law, streets are littered, the sweepings of stores are put in the gutters, houses and grounds are ill cared for, and in many ways pride in one’s home seems to be lacking. The maintenance of the cleanliness of the environment by attention to these petty details by individuals and property owners might well be termed ‘Collective Sanitation.’ How can civic pride be obtained without individual pride, and how difficult is public sanitation without the individual instinct for cleanliness!