This knowledge has already done much to prolong life. The average length of life in India, where no attempt is made to check disease, is twenty-five years. In England the length of life has doubled in a few generations. In Sweden, where the people live a sanitary life, the average is over fifty years, in this country, forty-five years.

Insurance companies and benefit societies keep close watch of their members and they report that a person ten years old may now count on living to be sixty years of age. That is the average age, whereas a hundred years ago the average expectation of life at that age was only fifty-three years.

And this is true in spite of the fact that people have been crowding into cities, that they are living on richer foods, taking less exercise in the open air, living in houses which shut out the fresh air, and doing dozens of other things that have tended to lower rather than to raise the average.

We can scarcely realize the possibilities of life if, with all the present scientific knowledge of disease and health, we could have a generation of people living according to nature's laws.

Life can be not only lengthened but strengthened. There are many instances of frail, feeble children who have developed into exceptionally strong men and women. One of the most noted is Von Humboldt, the great scientist, who as a child was very weak physically, and, he himself says, was mentally below the average, but who lived to the age of ninety, and developed one of the greatest minds of his century.

Doctor Horace Fletcher, noted for his theories in regard to eating, was rejected at the age of forty-six for life insurance but so strengthened his const.i.tution by careful living that by the time he was fifty he not only obtained his life insurance but celebrated his birthday by riding one hundred and ninety miles on his bicycle.

If we could imagine a person who all his life had lived in a locality where the air was pure; in a house where fresh air entered day and night, and which was heated to a uniform temperature; whose food had always consisted of the most pure and nutritious material prepared in the most wholesome way, eaten slowly and in proper quant.i.ty; if bathing, sleep, rest, exercise, brain work and pleasure had each its due proportion; if he could be always guarded from contagion and accidents, we can imagine that such a person would be free from disease and that death might be long deferred. Of course, death can not be prevented, only postponed, but disease can be prevented, and so we can increase the chances of postponing death. Doctors tell us that under ideal conditions there would be only one cause of death--old age.

There is no question that under such conditions life could be prolonged far beyond what is now usually considered its span. One hundred years or more might easily, we imagine, become the average of life, instead of the great exception.

We can hope for these things in the future though it will take several generations at least to bring them all about, but we need not wait so long for some of the best results. There are many things that can be done at once to prolong life and prevent illness. Since we know that many diseases are preventable and we know the suffering and sorrow, as well as expense, that come from sickness and premature death, we should all eagerly unite in doing all that we can to stop these ravages.

There are two agencies that will help to bring this about: individual or private means, and general or public means. Both are absolutely necessary if we are to be successful in stamping out disease. Professor Fisher says: "Personal hygiene means the strengthening of our defenses against disease. Public hygiene seeks to destroy the germs before they reach our bodily defenses."

In the first place, in order to learn what we may do to lengthen the span of life we must learn something of the nature of disease. Doctors tell us that diseases are of two cla.s.ses. The first are hereditary, or inherited; those which pa.s.s from parents to their children and often run through an entire family. It is more often the _tendency_ to disease that is inherited, rather than the disease itself, and so even these inherited diseases may often be prevented by careful living.

Diseases which may be inherited include rheumatism, gout, scrofula, diabetes, cancer and insanity. This cla.s.s of diseases is the most difficult to prevent and to cure. For some of them no cure has been found.

The other cla.s.s comprises the diseases of environment, or personal surroundings,--that is, our manner of living both as regards our private life and our relations to other people. These diseases are largely preventable and it is with them that most of the work of prevention is to be carried on.

A disease is considered preventable if, by using the best known means of treatment, it might be prevented or cured, so that either the disease or the death usually resulting from it would be avoided.

Of course, not all deaths from a given disease could be prevented even with the best known means. Infant diseases const.i.tute one cla.s.s which is considered most hopeful of betterment through a pure milk supply and better hygiene; and yet many authorities believe that not more than half the deaths could be prevented owing to the large part played by weather conditions, feeble const.i.tutions, and other unchangeable conditions.

Preventable diseases may be divided into six cla.s.ses:

(1) Diseases caused by lack of proper hygiene.

(2) Diseases caused by bad habits.

(3) Contagious diseases.

(4) Diseases caused by insects.

(5) Accidents, wounds, or operations and their resulting diseases.

(6) Diseases remedied by slight means.

We will treat each of these in turn.

(1) By proper hygiene is meant the proper treatment of the body as to breathing, eating, drinking, sleeping, bathing and rest. This treatment includes plenty of fresh air, both day and night, keeping outdoors as much as possible, and in well-aired houses the rest of the time.

Vigorous but not violent exercise, brisk walking, regular physical exercise, such as is practised in gymnasiums, will go far toward keeping the body in good condition.

The question of fresh air in the home is one of the most important points to be considered. The bedrooms, the living-rooms, and the kitchen should have the air changed constantly, not once or twice a day. In order to prevent drafts, and that the house may not be kept at too low a temperature in winter, a board, eight to twelve inches in height, may be placed across the bottom of a window that is raised.

Many diseases, not only of the throat and lungs, but of the other organs, may be prevented by the constant introduction of fresh air into our rooms day and night.

Tuberculosis causes more deaths than any other single disease in America, and the sickness and disability continue longer than with most diseases. It is extremely contagious, being a germ disease, and not an inherited one, as was formerly supposed. It increased very rapidly for a few years but is now slightly decreasing, owing to better knowledge of its cause and cure.

Its prevention and its cure both lie largely in fresh air. Physicians say that no one who lives an open-air life with plenty of fresh air night and day will contract it. The cure which is restoring hundreds to health is to find a place where the air is pure, and live and sleep practically outdoors; to eat as much milk, raw eggs, and meat as can be digested and to observe the other rules of hygiene. Incipient cases, those in the earliest stages, may sometimes be cured while continuing at work by following the other rules as nearly as possible.

On account of the extremely contagious nature of tuberculosis, special care should be taken to prevent its spread. The sputum coughed up from the lungs is the princ.i.p.al carrier of the disease, and the person who, having tuberculosis, even in its earliest stages, spits in a public place, is an enemy of mankind, for he endangers the lives of hundreds of others. The only excuse for this is that he usually does it through ignorance, but the knowledge of the danger should be so impressed on all the people that no one could plead ignorance, and for a consumptive to spit on the street should be counted as much a crime morally as for a smallpox patient deliberately to expose others to the disease.

Great care should of course be taken in the home of a consumptive patient to prevent the infection from spreading through the family.

Separate sleeping-rooms, thorough disinfection, and the use of paper napkins which are burned at once, to take the place of handkerchiefs, should be some of the means employed.

Pneumonia, pleurisy, bronchitis, grip, colds, and catarrh are some of the other ailments which may be largely banished by living the outdoor life. The method of treatment is medical, is different in each case, and should be decided by the family physician. The constant habit of breathing impurities, day after day and year after year, brings about a gradual change in the tissue of the lungs.

In the same way, simple food to take the place of the rich, heavy foods eaten in large quant.i.ties, will prevent many of the diseases of the stomach, liver, and kidneys, and improve the general health and strength. A diet of less meat and more eggs has been tried by football teams in training and found to give an equal amount of strength with greater endurance. A diet of milk, cereals, vegetables, nuts, and fruits, raw or simply cooked, with a small amount of animal foods, will perhaps give the best results in this climate. Food fried in fats, rich pastries and gravies are the hardest to digest, and better health will usually follow discontinuing them.

The purity of the food eaten should receive careful consideration.

Artificially preserved foods are usually more or less dangerous, for although dealers urge that the poison contained in them is too small to do harm we must remember that it is not the single dose that does harm, but the many foods each containing a very small amount of poison, taken day after day.

Pure food laws, national and state, have done great good in driving adulterated and impure foods out of the markets by requiring all foods to be properly labeled.

Thorough mastication or chewing of the food is only a little less important than the character of the food itself. Rapid swallowing without chewing in childhood lays the foundation for many of the digestive diseases of later life. If food be thoroughly masticated much that would otherwise be hard to digest can be eaten without bad results.

One of the best known examples of this is meat, which, while full of nourishment, sets up in the large intestine a condition known as "auto-intoxication," a species of digestive poison. If meat be eaten slowly and chewed thoroughly, this condition is almost entirely absent.

Pure drinking water is almost as necessary as pure food. We take water into the body for three princ.i.p.al purposes: first, it is needed to dissolve and dilute various substances and carry them from one part of the body to another; second, it forms a large part of the blood and other important fluids of the body, and is a part of many substances formed in the body; third, it serves to carry from the body the worn-out and useless tissues, the waste products of the body.

These are extremely poisonous and must be promptly disposed of to prevent sickness. This can not be done except by an ample supply of water. Few persons, especially grown persons, drink enough water. Ten gla.s.ses of pure water are needed properly to supply the body.

"Insufficient water drinking is perhaps the commonest cause of the interruption of the normal life processes," says Doctor Theron C.

Stearns.

But the common drinking cup in public places probably causes far more disease than the drinking itself prevents.

Particles of dead skin and disease-germs are left in the cup by each drinker. Some of the most serious diseases may be carried in this way. A cup made of heavy waterproof paper, cheap enough to be thrown away after being used once, is a recent invention that is highly recommended for use by school children and those who are obliged to drink away from home. The water in a public drinking-fountain should come out in a small steady stream so that those who have no cups may drink from the stream itself as it rises. Many school-houses are so equipped.

Sleep is a necessary part of good hygiene. It promotes health and prevents disease. It is largely in sleep that the system renews itself, that growth takes place, that waste products are thrown off, and the body repairs its wastes. No less than eight hours for grown persons and ten for children should be employed in sleep. Late hours and sleepless nights are the frequent cause of nervousness, eye strain, nervous prostration, and the beginning of brain troubles and insanity.

Bathing is also necessary to good health. The pores of the skin play a large part in carrying off the wastes of the body, through the perspiration, and if these become clogged, this poisonous material remains in the system. We have all noticed how a bath refreshes and gives tone to the entire body by opening the pores.

The skin is composed of minute scales, arranged in layers like fish scales. The tiny crevices between these form a lodging place for dirt and germs. If these remain, our own bodies are constantly exposed to their infection, if they drop off, as some are constantly doing, we may spread the contagion to others. This is strikingly ill.u.s.trated by scarlet fever, smallpox, and similar diseases where these minute scales are the sole source of contagion.

Exercise is another necessity of health. Regular physical culture in a gymnasium will develop any muscle or part of the body almost at will, but if this be not possible much can be accomplished in developing the body by simple work. Gladstone found health in chopping wood, Roosevelt in a daily tennis game, and President Taft in golf. Many find it in gardening or farming. These all help to develop vigorous bodies.

Anything which brings into moderate play any set of muscles, which increases the circulation, or stimulates the secretion is beneficial.

House-work, which, in its various forms, brings into use all the muscles of the body, is a wholesome exercise for women. Those who do no house-work seldom subst.i.tute for it any other active exercise, and many diseases which are caused by deposits of waste tissues that are not thrown off by the body, are the result.

Rest--recreation--pleasure--these are as necessary to health as anything else, but the American people are slow to learn the need of them. We hear much of nervous prostration as an American disease. It is due to a variety of causes,--high living, late hours, ill-ventilated rooms, and climate; but chief of all the causes is the long hours of work under strong pressure. Work done in a hurry and without rest may accomplish many things, but it invariably causes a corresponding loss of nerve force. Fatigue, by checking bodily resistance, gives rise to all kinds of poisons in the system. Every part of the body feels the ill effect of continued exhaustion.

Of the diseases caused by bad habits, it can only be said that all the evils they cause, directly and indirectly, are entirely preventable; that they are usually wrong morally, and that the suffering which results is sure.

Under this head come the effects of drinking, of the use of tobacco and drugs, and of bad personal and social habits. It is only necessary to refrain from these bad habits to prevent all the diseases that arise from them, with all their train of suffering, poverty and crime.