A text-book of hygiene : domestic hygiene and sanitary information, including articles on the human body, digestion and nutrition, the causes of disease, the effects of intemperance, food and diet, cleanliness and clothing, exercise, recreation and training, the home and its surroundings, the prevention of infectious diseases, etc.

Front matter

NATIONAL LIBRARY OF MEDICINE

A TEXT-BOOK OF HYGIENE.

DOMESTIC HYGIENE

Chapter I. Introductory

Wision:of Mirza’: 2 =. LY.

Casualties which befall a- Beier in its March fasaey Life at different Stages . Bes ares Soke cee F Pe Natural Duration of Life : : : ; ; see Uses of Vital Statistics . ; * REE ioe . 24 Caleulation of Annual Deaticpis Say aban eee. eet as Mee Calculation of Zymotic Death-rate . eee ; Rae

Zymotic Diseases defined . ; 3 : 3 ; : $26 Rate of Infant Mortality . i $26 Difference between Rates of Mortality 3 in ‘dittonent Diatricta eats Amount of Preventable Disease. : ; : ee)

Possibility of lowering General Deaths : ‘ ‘ eee

CHAPTER II. THe Human Bopy

- I. Chemical Composition . : : ; : poche . 33

Vital Force . : : : : 3

Protoplasn =. ; - = . c 5 . 739 vii viii : CONTENTS.

II. Food Constituents ; ie 3 ; P

Functions of Nitrogenous @ensttinsiite :

Functions of Fatty Constituents. : : ; :

Functions of Farinaceous Constituents

Functions of Water and Saline Constituents

III. The Tissues

The Connective Tissue

The Skin .

The Muscular Tissue

The Bones

The Nervous Satan

TV. Digestion and Nutrition

Mastication 5

Function of Rae Giagds :

Swallowing : “ : :

The Stomach and the Guseia . uice F . A 5

Secretion of Liver -. ; :

Changes which Food endear in iiapet nied ;

How Food is absorbed into the Circulation and qonvenied ‘nts Blood

Assimilation 5 F i 3 : : 2

V. Composition of the Blood ; ; : 5 ; 5 :

VI. Circulation of the Blood ;

Structure and Mechanism of the Heart .

Structure and Distribution of the Arteries is 4 A 5

The Pulse

Capillaries. :

Structure and Distribution of ie Veins c

Rhythmical Action of the Heart

VII. Respiration, Oxidation, and Excretion

Structure and Action of the a)

Functions of, Respiration .

Composition of Air . 5 :

Difference between Inspired aad Bepined oe

Changes which the Blood undergoes in its Passage through ie

Lungs Excretion . : A : 4 ; Relation of the Vital Pease ‘ ; A A :

Interchanges of Dead and Living ater Mee . :

Chapter III. ‘causes Of Disease

Advantages of Sound Health .

Uncontrollable Causes of Disease

Atmospheric Changes

Controllable Causes .

I. Hereditary Influence

Illustrations in Domestication of Rover Agninnts Family Characteristics

Atavism : 5

Limits of icpcitiary Peanaaisiion:

Hygienic Application of Laws of Heredity

Ages at which Special Hereditary Tendencies are fable: to ie developed . : 3 Course of Hereditary Transmission Consequences of Unsuitable Marriages . Obligations on entering the Married State Il. Seljf-Induced and Social Causes of Disease 1. Intemperance ; Statistical Details Physiological Action of ‘Alcohol Diseases induced by Intemperance . : Estimate of Annual Mortality from Taeeareines : How to cope with the National Evil of Intemperance 2. Tobacco and Narcotics Injury of Smoking to Boys * Precautions - ; 8. Errors in Diet Excess of Food Eating at Irregular Hours Careless Feeding of Infants 4. Mental Worry and Overwork Symptoms and Results Effects of Physical Strain. 5. Idleness 6. Immorality . 7. Irregular modes of Te ix x CONTENTS.

Late Hours Amount of Sleep ee

Importance of cultivating Habits of Fiegtilarity aad Pundit:

ality 8. Errors in Olihice

III. Material, Local, and Cvirnnumisase Goi of Bens :

1. Impurities in Air

Evils of Overcrowding . : : 5 Consumption .

Typhus Fever.

Diseases induced by oe hse sd Foul Effluvia

Diseases induced by particular Trades . ‘Diseases induced by Dampness of the Air

2. Impure Water

Impurities in Water

Diseases induced by Polluted Water

3. Unsound Food 4

Agency of Milk in the Sores of Bisaes Diseases induced by Unsound Butcher’s Meat Diseases induced by Unwholesome Fish Diseases induced by Unsound Vegetable Food Effect of Adulteration Acts rene 4, Disease-Germs ; Mode of Propagation of Infections Theirs :

CHAPTER IV. ‘Foop AND DIET

I. Nutritive Values of Foods Table of Alimentary Equivalents .

Amount of Food regulated by Amount of Work

Proportion of Several Food Constituents required in a

Healthy Diet .

Necessity of a Mixed Diet Il. Choice of Food and Drink 1. Vegetable Foods Flour

PAGE

119 122 123

124 126 126 126 127

CONTENTS.

Characteristics of Wholesome Bread Oatmeal . F A - 7 Barley Meal . ; : c

Rye Meal

Maize : Rice and other agian Paola:

Pulses or Legumes, such as Peas, Beans, and Lentils

Potato

Turnips, Carrots, Gipies ae Mushrooms

Ripe Fruits

Sea-weed and Lichens

Sugar and Treacle .

Pickles and Condiments .

2. Animal Foods

Milk :

Condensed Milk

Characteristics of Good Milk .

‘Butter

Cheese

_Butcher’s Meat

Characteristics of Good Bucher $s Meat Most Economical Parts for Cooking Bacon

Poultry .

Game

Fish

Turtle

Eggs 3

Preserved Meat.

38. Water, Beverages, and penelant Sources and Qualities of Drinking Water Mineral and Aerated Waters .

Non-alcoholie Drinks

Tea : Chanattdsintiés of Good Tea % Coffee

Cocoa ;

Alcoholic Beverages

. 429

Amount of Alcohol which can be consumed daily without Detriment to Health

Distilled Spirits

Wines

Safest Wines . Drink

Beers, Porters, and Ales

IIL. Preparation of Food

Faults in Cooking .

Soup Kitchens and Cooking Depots

Formule for Soup Kitchens .

Hints for Economy in the Diet of the Ai ee L: sharers

How to make Broths and Soups ; :

General Details with respect to Boiling, Fooly Stewing, and Braising

IV. Hints on Diet -

Necessity of Variety

Relative Digestibility of different Reiicles of Diek

Hints on the Feeding of Infants

Diet Suitable for Children

Errors in School Diet ,

Diet during the Period of Youth ;

Distribution of Meals.

General Rules : : or ee

>~CHAPTER V.

CLEANLINESS AND CLOTHING.

I. Cleanliness .

Necessity of Body Cheagiiiees : | ;

Public Baths . : : E

Hints with respect to the Tats of ihe Bones Cold, Stiswen Plunge, and Tepid Baths : : :

Swimming $

Instructions of the Royal flinaiae Sbeiuey “ai regpiadt ts Bathing :

Turkish, ‘Vapor, ad oilien Baths ;

Hints on Cleaning the Teeth .

PAGE

CONTENTS:

IL.. Clothing :

Qualities of Different Articles of Clothing i in respect to Bodily Warmth .

Clothing Suitable for Wasi Weather

Clothing Suitable for Cold Weather

Hints concerning Bed Clothes

Hints concerning Boots and Shoes .

Injurious Effects of Tight Lacing .

Necessity of fashioning Dress in conformity with the Natineah Lines and Proportions of the Body .

CHAPTER VI. Exerrcisg, RECREATION, AND TRAINING

I. National Physique. ag

Is the British Race dbeciorsing ?. 2.

Average Stature of Adult Englishmen .

Necessity of Recreation .

Il. Physiological Details . é :

Necessity of Muscular Activity or Exercise . :

Amount of Exercise required for the Maintenance of Healike.

Necessity of Variety of Exerciseand Recreation according to Individual Peculiarities or Avocations .

Ill. National Aspects of the Question

Reading Rooms, Public Parks, Museums, National Paces etc.

Ae antages of doing a Velnaleer Gas

IV. Exercise during Childhood

School Furniture .

‘School Drill

Play-grounds . :

V. Exercise for Boys - .

Dangers to be guarded against

Suitable Kinds of Exercise

Gymnasium

- VI. Exercise for Gir ls :

Evil Effects of Neglect of Suitable Pixcicise aud Baciitiva .

Kinds of Exercise recommended at School

195 196

VII. Exercise for Women SC : Neglect of Bodily Exercise a Fruitful Sohne of Disdane VIII. Lzercise for Men .

Timely Warnings

IX. Exercise in Old Ae - : !

X. Training . 4 ; a eens : Physiological Details ‘ General Hints on Training : : : :

Evil Effects of Over-Training ‘ : : . Athletic Contests

Hints on Diet during Painting ; System of Training pursued at the Brglich Universities

CHAPTER VII. Tur Home AnD Its SURROUNDINGS

Historical Sketch of English Homes. :

Te Sales: : ; : : ; ‘ : ‘ Sites to be aneidedl. 3 alee : ‘ Hints with respect to Choice of Site or Dwalling :

II. Structural Details. pea

Foundations . mee Areas

How to prevent Dampness of Walls

Arrangement of Rooms .

Structural Details with Respect to Ventilation ‘arid Wieming 3

Situation and Construction of Closets

TL. Drainage .

Laying, Ventilation, ‘nl pee of Histee:, Beate ‘Cesspools ; ; é : f : : ‘ LY Water Supply. 5 ow es el GaN eR Constant and Intermittent Systems in Hogans

Dangers to be guarded aac : : .

Water Supply in Country Districts

Hints with respect to Wells, etc.

Sources of Supply . : f :

Filiers’ . 5 garthe ‘ : ‘ j

CONTENTS.

V.° Ventilation, Warming and Lighting . Amount of Fresh Air required é

Amount of Cubic Space required . : : ' ‘ Various Methods of Ventilation 3 ‘

Ventilation and Warming by Fire-places. ‘ . Ventilating Grates . - :

Hints with respect to Lighting , ‘ . ‘

Tests for Ventilation . : : . : : : s VI. Outside Premises. : : eae . Agee Paths, Yards, Dust-bins .. . : : : : . : Outside Closets : : ‘ : . : ; : Keeping of Animals. : . : : VII. Hints about Choosing a Hise

VIII. Nuisances and Sanitary Defects remodel tiie: the Si tary Acts . ; : 2 .

Nuisances removable by Hisaaaholders ; A ‘ Defects removable by Owners . : ; 5 : :

’ Sanitary Authorities . ‘ ; ‘ :

CHAPTER VIII InFectious DISEASES AND THEIR PREVENTION

Prevalence of Epidemics during Past Ages and Recent

Rimes = ‘ : : ‘ ; Black Death . , , A ; pe ae Sweating Sickness . ‘ F . ‘ Scurvy . ‘ : ‘ : : Jail Fever. : : ; 3 ; ‘ Cholera . 4 R : ; A , ; I. Principal Bante Biseosis : : : : ‘ ‘ Classification and Remarks thereon snmane 1. Small-Pox . 5 A

Prevalence of the Diccace daving Past Century Introduction of Inoculation

Discovery of Vaccination A ‘ * Statistics proving the Value of Vudcihation : Risks attending Vaccination . : : : : Mode of Propagation of Small-pox ; F ‘ ;

xv

Precautionary Measures . . Measles : . Whooping-cough . Scarlatina or Scarlet Fever . Diphtheria . Fever. : a) Typhus Fever . b) Relapsing Fever (ec) Typhoid or Enteric igen! 7. Diarrhea Channels of Infection Il. Practical Disinfection III. General Pr ee. Weesuia Penalties Concluding Be macks

Chapter 1. Introductory

Many of my readers, I have no doubt, are well acquainted with Addison’s beautiful allegory, “The Vision of Mirza.” Looking eastward from the highest pinnacle of the rock on which his guide had placed: him, Mirza beheld a huge valley, and a prodigious tide running through it. The valley, he was told, was “the vale of misery,” and the tide of water which “rose out of a thick mist at one end, and lost itself in a thick mist at the other,” was but part of the great tide of eternity called Time. Peering across this shoreless ocean, Mirza then discovered a bridge standing in the midst of it, but shrouded at either end by a dark cloud, and the bridge, he was told, was human life. Being asked to survey it more closely, he found that “it consisted of three-score and ten entire arches, with several broken arches, which, added to those which were entire, made up the number about an hundred?’ And over the bridge he beheld multitudes passing, and several of the passengers drop- _ping through into the great tide that flowed underneath, -for “there were innumerable trap-doors which lay con- “2 17

18 is INTRODUCTORY.

cealed in the bridge, which the passengers no sooner trod upon but they fell through them into the tide, and immediately disappeared.” He noticed further that these hidden pitfalls were set very thickly at the entrance of the bridge, so that throngs fell through them as soon as they broke through the cloud.. They became fewer towards the middle, but multiplied and lay closer together towards the end of the arches that were entire, while over the broken arches there were some persons, though very few indeed, that “continued a kind of hobbling march, but fell through one after the other, being quite tired and spent with so long a walk.”

Such was the opening vista in “The Vision of Mirza,” and weird and shadowy though its outlines be, it represents very vividly what has been called the march of a generation through life, and the casualties under which so many succumb even in the first few stages. It is true that the trap-doors or hidden pitfalls suggest a somewhat fatalistic view of the deadly “ills which flesh is heir to,” but in Addison’s days, and indeed until quite recently, disease was regarded as inevitable far more than avoidable—curable it might be in some instances, but rarely admitting of prevention or control. The very few who reached the broken arches were looked upon pretty much in the same light as soldiers who had luckily escaped the shot and shell of a thickly strewn battle-field. Now, however, we are beginning to realize that most of these pitfalls may be avoided, and the trap-doors made secure and passable, so that many, instead of the ever-lessening - few, may travel on towards the broken arches.

But to leave metaphor aside, and come to the dry details of figures, let us glance briefly at the casualties which befall an English generation in the various stages of its march through life. These have been very carefully and fully worked out by Dr. Farr, in one of his .

MARCH OF A GENERATION THROUGH LIFE. 19 recent masterly reports accompanying the Returns of the Registrar-General, and the sum and substance of them are as follows:—Out of every 1000 children born, 149 succumb on the average before the first year of life is reached, and before the age of five years as many as 263. Many die from a diseased heritage, many from starvation and neglect, and many more from diseases, such as scarlet fever, measles, and whooping-cough, which we shall after- ‘ wards see are more or less preventable. But the number of victims varies largely in different localities. Thus, in the so-called healthy districts of the country, out of 1000 ‘born, the number of children who die in the first five years of life is 175 instead of 263; while in Liverpool, . which represents the most unfavorable sanitary conditions, the number is 460, or 285 in excess of the deaths in healthy districts. Such enormous waste of infant life may truly be called appalling.

Returning now to the 737 survivors, who on the average reach the sixth year, we find that most of them have been attacked by one disease or another, and diseases of a kind which fortunately seldom recur in the same individual. So the total deaths in the following five years are comparatively few, and only amount to 35, about a fourth of which are due to searlet fever, which still attacks some who had previously escaped. From ten to fifteen years of age, the deaths are fewer than at any other period, and only number 18. But after the age of puberty has been passed, the mortality begins to increase, especially amongst women, and consumption claims a considerable share of the death-roll; indeed, between the ages of twenty and twenty-five, nearly one-half the number who die succumb to this fatal disorder, and fever is associated with it as the great preventable disease. Melancholy suicide begins to contribute its victims, the worries and anxieties of life induce fatal brain affections, deaths by accident among males become more numerous. insanity ~ in both sexes looms on the horizon. and childbirth among women has its fatalities.

At twenty-five years of age, we find the number of travellers on life’s journey reduced from 1000 to 634, and 62 drop off before the age of thirty-five is reached. This stage embraces the prime of life, the period of manly vigor; yet consumption still proves the most fatal disease, ‘and more so among women. Two-thirds of these are now married, and the deaths from childbirth exceed the deaths from accident among the men. Fever, though not so fatal as it was in the previous period, causes 4 out of the 62 deaths, while consumption claims 27. Other diseases of the lungs, and diseases of the heart and brain, increase in intensity.

And here, by way of contrast, let us glance at the fate of a generation exposed to unfavorable sanitary conditions, such, for instance, as prevail in large and crowded populations like Liverpool. There, out of the 1000 born, only 434, or Jess than one-half, reach the age of ‘twenty-five, and only 360 are alive at thirty-five; whereas in healthier districts as many as 727 live to the age of twenty-five, and 667 survive ten years longer.

Between the ages of thirty-five and forty-five, the 572 survivors at the former age are reduced by 62; and now we come to the middle arch of life, when the ranks are thinned of one-half their number. A few months after the age of forty-five is reached the 1000 lives are reduced to 500, and when fifty-five is reached the numbers are still further reduced to 421. The passing generation has now produced the succeeding generation. Many of the structures begin rapidly to give way. Consumption still holds its fatal prominence, while lung diseases, heart diseases, brain diseases, and liver diseases are becoming more common and deadly. Fever continues to claim its

MARCH OF A GENERATION THROUGH LIFE. 21 victims, deaths by accident are not uncommon, suicide is slightly on the increase, and cancer (especially amongst women) begins to swell the death-roll. -

From the age of fifty-five and onwards, the numbers thin with increasing rapidity. Out of the 421 who enter this stage of life, only 309 reach the age of sixty-five; and 161 the age of seventy-five. Diseases of the lungs destroy the largest number of lives. Many die from heart disease, brain disease, and diseases of the liver and bowels. Intemperance and disregard of the laws of health claim their later and larger harvest. Cancer becomés increasingly fatal amoupst women, and not a few of both sexes die of no well-defined disease, their deaths being attributed to debility or old age. The few remaining pilgrims have at last reached the broken arches described in “The Vision of Mirza.” Only 38 out of the 1000 reach the age of eighty-five, and one by one they continue to drop through, “being quite tired and spent with so long a walk.” The wheels of life are run down, and the greater number sink to rest calmly. and placidly “after the fashion and semblance of a kindly and pleasant sleep.” At the age of ninety-five, but 2 survive out of the 1000, while only one out of every 300) born reaches the age of one hundred.

And what, it may be asked, are the inferences to be drawn from these figures, and the various casualties which they represent? In the first place, it will have been noticed that the mortality at different ages is largely influenced by the sanitary surroundings and conditions of the people. In densely crowded towns, for example, the average duration of human life sinks to nearly half the standard of healthy districts; and this is the result - of the enormously increased mortality among children under five years of age, and the excessive mortality in youth and manhood up to the ultimate term of life, but few reaching and few surviving the “three-score years and ten.” It will be seen also that certain diseases prove very fatal in certain epochs, and that others, though common to different epochs, are far less destructive at some periods of life than at subsequent periods. Thus, measles, whooping-cough, and scarlet fever are essentially fatal during childhood; while diseases of the lungs, though common to this period, become increasingly fatal as old age creeps on. But without proceeding ftrther with this analysis, and leaving the facts and figures which have been given to tell their own*tale, the question arises, .what may reasonably be supposed to be the natural term of a man’s lifetime? Not a few of the alchemists of the Middle Ages, and some philosophers of more recent times, such as Descartes and Franklin, believed that: human life could be prolonged indefinitely, and we read of men wasting their years and shortening their lives in trying to discover an elixir vite, which would ensure immortality on earth, and a, manhood of perpetual vigor and strength. But delusions like these have long since been dispelled by the plain teachings of science, and we now know that though life may be prolonged by careful regimen and obedience to the laws of health, a time comes in the history of every individual, however long-lived he may be, when vital energy becomes powerless to resist the stealthy progress of decay, and the body sinks at last into the cold bosom of mother Earth. z

As regards the length of this period which intervenes between birth and natural death, statistics help us to make only an approximate estimate. Dr. Farr, who is perhaps better able than any other authority to give an opinion on this point, has estimated the natural lifetime of man to be a-hundred years; and certainly, when it is remembered that some few well-authenticated instances are recorded in which the lifetime of a century has been exceeded, and many are known in which it has been approached, this estimate cannot be regarded as excessive. Be this as it may, old age may be said to commence at about sixty, with some a litle earlier, with others a little later, and even though there be a continued freedom from disease, the bodily powers gradually and imperceptibly begin to wane, the step becomes less elastic, the heart beats more slowly, the digestion becomes weaker, the breathing shallower, until at last, after a varying period, the natural life terminates in natural death. Frequently the intellectual faculties retain their vigor long after the bodily powers begin insensibly to decline, but by-and-by they too show signs of decay. Recent events are readily forgotten, and passing incidents are strangely linked with newly awakened memories of long ago. The inclination to sleep becomes stronger and stronger, and the periods of wakefulness. shorter and shorter, until at length the sleeper has drifted painlessly and peacefully into the sleep that knows no awakening. This is the true Euthanasia —the natural death, which completes the cycle of natura

life. .

We now pass on to the consideration of some further statistical details which will be of service in enabling the reader to appreciate the value and significance of the stated returns of the Registrar-General which find a place ‘in the leading daily journals, and of the reports of medical officers of health throughout the country which appear from time to time in local newspapers. ;

It will be inferred from the previous remarks that very few die from old age; almost all, including even old people, suecumb to some particular kind of disease. As we shall see subsequently, the disease may be inherited, or it may be self-inflicted by vicious habits or carelessness, or it may be produced by local causes, or it may be the result of exposure to infection; but whatever the cause, the more closely the sequence of events is scrutinized, the clearer it becomes that a very large proportion of deaths is attributable to influences brought into operation by man himself, and therefore more or less under his control. ; Now, it is the special province of what-are called vital statistics to enable us to arrive at reliable conclusions, based on numerous well-ascertained facts, concerning everything which affects the health and well-being of the community. Ever since the days of Queen Elizabeth, births, deaths, and marriages have been partially registered in the different parishes throughout England; but it was not till 1837 that the Legislature passed an Act which provided that for the future all these entries should find a place in a national register, and that as regards deaths, the various causes or diseases should be certified by the medical attendant. -That the important office of the Registrar-General of England, which was established by that Act, has been productive of a vast amount of benefit to. the health of the nation, and indeed hag largely stimulated other countries to follow in the wake of sanitary progress, there can be no doubt. By means of the statistics which are forwarded regularly to the central office from all parts of the country, the mortality in different localities from various diseases and at different ages can be readily compared, and the relationship to sex and occupation can also be determined. But in addition to the reports of the Registrar-General, which are of national interest, the Public Health Act of 1872 inaugurated another and more intimate kind of sanitary supervision, by the appointment of medical officers of health alike in towns and country districts, whose reports, bearing on the vital statistics of their several districts, are of local intere est and concern.* In order that the inferences or deductions which are based on these statistics may be fairly accurate and reliable, it is of course necessary that the number of the population should be known or approximately estimated. This is ascertained positively every ten years by census, and for the successive intervening years it is calculated by adding the known yearly rate of increase which has taken place in any town or district, while as regards the estimate of the general population of the kingdom, other corrections have to be made in respect to.emigration and immigration.

Generally speaking, the vital statistics which may be taken ‘as an approximately fair index of the sanitary condition of any locality are—the total death-rate, the death-rate from so-called zymotic disease, the infant mortality rate, and the percentage of deaths of children _under five years of age. Of course, there are many other problems which may be worked out, such as the death-rate from any particular kind of disease—as, for example, cancer, consumption, or heart disease, or thé average age at death of those employed in different trades and occupations; but these are the most important.

What is called the total or gross annual death-rate of any locality is calculated on the number of the popu- ' lation living, without distinction of age or sex, and is expressed as so many per 1000. The zymotic death-rate is based on the number of deaths which are attributed to the seven principal zymotic diseases, namely, small-pox, measles, scarlatina, diphtheria, whooping-cough, fever, and diarrhea, and is also expressed as so many per 1000 of the population. And here it may be explained that

*This invaluable care of the public health, which constitutes one of the most important functions of a wise and enlightened government, has been sadJy neglected in.the United States. As yet a few of our commonwealths only have active and efficient Boards of Health, but it is to be hoped that legislators throughout the country, will soon discern and remedy this lamentable omission.—(R.)

‘the term “zymotic” is applied to those diseases which are believed to be propagated by infective germs which develop as ferments in the body of the person infected, and give rise to all the symptoms of the special disease. The term is derived from a Greek word zwme, signifying a ferment, and the theory is that these germs or particles, although they are too minute to be detected by the most powerful microscope, bear a strong analogy to the cells of the yeast plant, which are capable of being transmitted from one tumbler of saccharine substance to another, and of growing and multiplying in that substance. It is true that all this is mere hypothesis ; but we do find practically that many diseases are propagated _ very much in this way. The contagion of small-pox, for example, has often been wafted from one side of a street to another, and both it and scarlet fever are frequently _ spread by articles of clothing which have been infected by tainted air in one house, and conveyed, it may be, long distances, to some other, in the ordinary intercourse : of life.* The infant mortality rate is usually measured by the proportion of deaths of infants under one year to births registered, and is also expressed as so many per 1000, or it may be expressed as a percentage of the total number of deaths,

The mean annual death-rate for the whole of England and Wales during the ten years 1861-70 was. 22.4 per 1000; but it need hardly be said that it varied very considerably in different localities. Thus, in fifty-four regis- -tration districts the mortality was at the rate of only 17 per 1000, and in a few it was as low as 15. In another series of districts it was 19, and gradually increasing pretty much according to density of population, to 22 and 25, it reached in Manchester a rate of 32.5, and in Liver-

' *See editor’s lecture on “The Germ Théory of Disease and its present Bearing upon Public and Personal Hygiene.” Penn Monthly for Nov., 1878.—(R.)

pool it reached the enormous rate of 38.6 per 1000. The significance of these figures becomes all the more manifest when it is remembered that, had the average death-rate of the whole of England and Wales been the same as that which prevailed in the healthy districts, namely, 17 per 1000, there would have been an annual saving of 115,000 lives. But even in the so-called healthy districts there are numerous local causes of disease which still call for removal, so that the estimate of 120,000 lives sacrificed annually to insanitary conditions and neglect of ordinary precautions cannot be considered to be by any means excessive. When, moreover, we reflect that many diseases which terminate fatally are induced, not by local causes or exposure to infection, but by disobeying the ordinary laws of health or the rules of domestic hygiene, it will become at once apparent that this estimate large, though it be—amounting, indeed, to about one-fourth of the ‘average annual death-rate—falls very far short of the mark in giving any adequate idea of the vast amount of preventable human suffering which is scattered broadcast throughout the country.