DISEASES FROM NATURAL ACCIDENTS.

Childbirth. (Mother.)

London.-Maximum.-Second week of October to end of March; absolute, December, January.

Minimum.-May, June, July, August; absolute, June to
August.

Premature Birth.

London.-Maximum.-January, February, May, July, August, December. Minimum.-During remaining months.

Curve shows little variation from the average through the year.

Privation.

London.-Maximum. -December to middle of April.

Minimum.-Middle of April to end of November.

Curve allied to that of disease of respiratory organs.

Want of Breast Milk.

London.-Maximum.-July, August, and September; absolute, July, August.

Minimum.-October to end of June; absolute, May.

This curve is allied to that from diseases of abdominal organs.

Alcoholic Diseases and Delirium Tremens.

London.-Maximum.-Beginning of May to end of September; absolute, July.

Minimum.-Beginning of October to beginning of May, with

rise to the average in October, and slightly above the average in first week of new year; absolute, January, February, March, December.

The curve for delirium tremens stands alone, resembles no other curve, and is steady.

Suicide.

London.-Maximum.-Latter part of March to latter part of August ; absolute, end of June.

Minimum.-End of August to March; absolute, beginning of
February.

New York.-Maximum.-Beginning of April to end of September; abso

lute, May.

Minimum. Beginning of October to beginning of April; absolute, February.

Both curves have the maximum period in spring and early

summer.

From the details of important facts above recorded we gather information of the most useful and practical kind. There is probably nowhere in medical science such an epitome of disease as that recorded in Messrs. Buchan and Mitchell's papers. From the researches of these distinguished men we can indeed forecast, in these islands, the course of many diseases with a precision that may to a large degree be called exact.

35

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and is not to be removed from the Library Room by any person or under any pretext clétérer.

CHAPTER V.

ATMOSPHERICAL, METEOROLOGICAL, AND CLIMATIC CAUSES CONSIDERED IN DETAIL.

FROM the array of facts which have passed under our observation we have been able to arrive at certain general conclusions, which are of extreme practical value. It will be instructive now to inquire whether the facts relating to disease can be accounted for as connected with particular atmospherical conditions. In other words, are the phenomena of disease dependent upon particular atmospherical variations, or upon particular combinations of them?

ATMOSPHERIC TEMPERATURE AND DAMP.

The influence of temperature on disease has ever been a fertile subject of observation by skilled inquirers. Dr. William Farr, however, was the first to treat upon it with precision, and to bring the effects of variation of temperature on life into what may be called a calculable form. In one of his early tables he described that after twenty years of age the danger of dying from a fall of temperature is doubled every nine years.

Thus, out of the same members living, if one die at thirty years, two will die at thirty-nine, four at forty-eight, eight at fiftyseven, sixteen at sixty-six, thirty-two at seventy-five, and sixtyfour at eighty-four, from the same wave of cold.

The wave of cold cannot, however, of itself be taken as the cause of all that depends upon climatic influence, and Messrs. Buchan and Mitchell, recognizing this fact, have commented on temperature and moisture, together, in relation to disease. They divide the London year into six periods, each one of which has a climate peculiar to itself. The periods are as follow:

The first period, extending from the fourth week of October to the third week of December, is marked by dampness and cold.

The second period, extending from the fourth week of December to the third week of February, is marked by cold.

The third period, extending from the fourth week of February to the second week of April, is marked by dryness and cold.

The fourth period, extending from the third week of April to the fourth week of June, is marked by dryness and warmth. The fifth period, extending from the close of June to the fourth week of August, is marked by heat.

The sixth period, extending from the first week of September to the third week of October, is marked by dampness and warmth.

During the first of these periods, marked by dampness and cold, seventeen diseases show a rapid increase of mortality, and twenty-five a mortality greatly above the average. Ten diseases, namely, measles, diphtheria, typhoid fever, childbed fever, rheumatism, pericarditis, aneurism, pneumonia, skin disease, and cyanosis, present an absolute maximum. Fourteen diseases, half of which are connected with the nervous system, show an increase of mortality. Twelve show a mortality considerably below the average, three of these being scrofula, cephalitis, and jaundice, and nine bowel complaints, or diseases connected with the nervous system.

In the second period, characterized by cold, six diseases begin to show an increased mortality, whooping-cough showing a rapid increase. Forty present a mortality considerably in excess. Seventeen, namely, small-pox, quinsy, typhus, delirium tremens, paralysis, insanity, convulsions, heart disease, bronchitis, pleurisy, asthma, other lung diseases, hernia, kidney disease, ulcer, childbirth, and old age, present the annual maximum. Seven diseases begin to decrease, five showing a rapid decrease. Twelve fall much below the average; five, namely, purpura and scurvy, delirium tremens, tabes mesenterica, hepatitis and suicide, reaching the minimum. Diseases of the respiratory organs show the greatest mortality during this period.

In the third period, characterized by dryness and cold, three diseases show an increase of mortality, and three of them a rapid increase. Thirty-four yield a mortality greatly in the excess. Fifteen, namely croup, whooping-cough, privation, dropsy, mortification, consumption, hydrocephalus, apoplexy, chorea, epilepsy,

convulsions, brain disease, laryngitis, Bright's disease, and teething, yielding a maximum. Twelve begin to decline; four present a rapid decline; eleven fall below the average, one of them, scarlet fever, declining to the annual minimum. Diseases connected with the nervous system show the highest death-rate in this period, and no complaint of which the nervous system is believed to be the seat has its minimum at this season.

In the fourth period, characterized by dryness and warmth, nine diseases begin to increase in their mortality; nine show a rapid increase. Fifteen rise above the average, nine of which, namely, ague, remittent fever, gout, purpura and scurvy, scrofula, cephalitis, intussusception, joint disease, and suicide, attain or retain their annual maximum. Nineteen begin to decline from the maximum; nine show a rapid decline. Eighteen are below the average, eleven of them, namely, diphtheria, typhoid, dysentery, diarrhoea, cholera, want of breast-milk, thrush, enteritis, ulcer, atrophy and debility, reaching their annual minimum. This is the healthiest of all the periods; the diseases of the respiratory and nervous systems rapidly diminish, and bowel complaints are at the lowest until just upon the close of the period.

In the fifth period, characterized by heat, four diseases begin to increase in their mortality, ten showing a rapid increase. Sixteen are above the average, diarrhoea, summer cholera, want of breast milk, delirium tremens, thrush, tabes mesenterica, gastritis, enteritis, jaundice, and atrophy and debility, attaining their annual maximum. Ten diseases begin to decline, nine showing a rapid decline. Thirty-one are below the average, twenty of which, namely, croup, erysipelas, childbed fever, rheumatism, dropsy, mortification, apoplexy, epilepsy, pericarditis, heart disease, laryngitis, bronchitis, pleurisy, pneumonia, asthma, other lung disease, Bright's disease, kidney disease, skin disease, and cyanosis, attain or maintain their annual minimum. The marked diseases of this period are bowel complaints. Delirium tremens has also its maximum in this period.

In the sixth period, characterized by dampness and warmth, twenty-one diseases begin to increase in their mortality, nine showing a rapid increase. Nine run above the average, three of these, namely, scarlet fever, dysentery, and cholera, attaining or maintaining their annual maximum. Six begin to decline from the maximum; seven show a rapid decline. Twenty-seven are