ATMOSPHERIC TEMPERATURE AND DAMP.
From the array of facts which have passed under our observa tion 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 atmospherical variations, or upon particular combinations of them? The influence of temperature on disease has ever been a fer tile 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 fifty seven, sixteen at sixty-six, thirty-two at seventy-five, and sixty four 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 Decem ber to the third week of February, is marked by cold.
The third period, extending from the fourth week of Feb ruary 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 fifthperiod, 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, rheu matism, pericarditis, aneurism, pneumonia, skin disease, and cyanosis, present an absolute maximum. Fourteen diseases, half of which are connected with the nervous system, show an in crease of mortality. Twelve show a mortality considerably below the average, three of these being scrofula, cephalitis, and jaun dice, 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. Sev enteen, namely, small-pox, quinsy, typhus, delirium tremens, paralysis, insanity, convulsions, heart disease, bronchitis, pleurisy, asthma, other lung diseases, hernia, kidney disease, ulcer, child birth, 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, pnrpura and scurvy, de lirium tremens, tabes mesenteries, 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, mor tification, consumption, hydrocephalus, apoplexy, chorea, epilepsy, convulsions, brain disease, laryngitis, Bright's disease, and teeth ing, yielding a maximum. Twelve begin to decline; four present a rapid decline; eleven fall below the average, one of them, scar let 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 re tain 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 period, characterized by heat, four diseases begin to increase in their mortality, ten showing a rapid increase. Six teen 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 an nual 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 dis ease, 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 niaximmn. Six begin to decline from the maximum; seven show a rapid decline. Twenty-seven are greatly under the average, fifteen of these, namely, small-pox, quinsy, whooping-cough, typhus, remittent fever, gout, consump tion, hydrocephalus, paralysis, insanity, convulsions, brain disease, hernia, teething, and old age, attaining or remaining at their annual minimum. Scarlet fever is the only disease which reaches its maximum death-rate during this period, viz., in October. The period altogether is very healthy.
A further analysis of these researches indicates that heat and not cold is the great destroyer of the infant life of London, while cold and not heat is the great destroyer of the aged.
We find an explanation of the effects of cold by estimating the force of vitality at different ages. We may assume that the body reaches its maximum of development at the age of thirty. At this period, if it be quite healthy, it generates by its own chemical processes so much force as shall enable it, within given bounds, to work its own machinery, to call forth at will a limited measure of extra force, and to supply a fluctuating loss that may be conveyed from it by contact with the surrounding air, and by other substances that it may touch, and that are colder than itself. The body yields, therefore, applied force, reserved force, and waste force; and these, under ordinary circumstances, are sufficient to maintain the perfect organism in effective life. So much active force gives the body the power to perform so much labor; so much reserved force supplies it with the power to perform a measure of extra labor to meet emergencies; so much waste force enables it to resist the external vicissitudes without trenching on the supply which is ever wanted to keep the heart pulsating, the chest heaving, the glands secreting, the digestive apparatus digest ing, and the brain receiving or thinking.
Let this distribution of force be disturbed, and straightway the life-power is reduced. If we use the active force too long, we become exhausted, and call upon the reserve; and if we still continue the process we fail at last, unless sleep forces itself upon us, and brings, with the rest it insures, renewal of power. If we are robbed of the waste force quicker than we can supply it again, exhaustion is produced; insufficient nervous control over the vas cular canals succeeds, and therewith that congestive condition of the lungs and other vascular organs, under which death is so easy when exhaustion is severe.
That the exhaustion should be more rapid in the man who has reached his prime is but natural. In his past he has been a growing, developing body, and in the course of development lie has used up an excess of force commensurate with the demands of his growth. When he stops in development, and stands on a fair level with the external forces opposed to him, then his own force, for a short time balanced, soon becomes second in command. Ile feels cold more tenderly; if his rest be broken, his demand for artificial heat is urgent; if lie lose or miss food, he fails rapidly; and, returning to our facts on the influence of external temperature on mortality, these many sources of failure are the reasons why a fall in the thermometer sweeps away our popula tion so decisively according to its age.
The influence of temperature is very decisive in regard to certain acute diseases. Thus, as Bondin shows, yellow fever de mands a temperature of 6s° Fahr. in order that it should take the epidemic form; while epidemic plague ceases in Egypt when the temperature approaches s2° Fahr. Plithisis pulmonalis, so fatal in Great Britain, diminishes as the climate becomes warmer, as in the West Indies, Ceylon, and Mauritius. It also diminishes as the climate becomes colder, as in Canada and Nova Scotia.