That learned Physician, Dr. Arbuthnot, in his Preface to Huygen’s “de Ratiociniis in ludo aleæ”, says, There are very few things which we know, which are not capable of being reduced to a mathematical reasoning; and when they cannot, it is a sign the knowledge of them is very small and confused; and, when a mathematical reason can be had, it is as great a folly to make use of any other, as to grope for a thing in the dark when you have a candle standing by you. Medical writers, almost universally, have neglected, or barely skimmed the surface of the following important subjects. The public registers of births, burials, and diseases, are overlooked by all the modern systematick authors: they leave us equally ignorant of the aggregate, or comparative number, or force of those fiends which haunt and ravage the globe. To speak metaphorically, in medical books, the extensive desolation of the most rapacious tyrants and conquerors are confounded with the uninteresting history, and petty depredations of a robber. The detached observations of physicians, or other literary individuals, confined perhaps to a small town or parish, a meagre detail of village remarks, furnish, in innumerable instances, foundations too slight for the erection and stability of general proportions. In order to form useful tables of the ratio of mortality at various ages, to determine upon the absolute and relative havock by different diseases, upon the general effects of climate, season, local situation, diet, drink, luxuries, new customs, and manners, &c. we should extend our views far beyond the narrow bounds of a parish, or even of a province; we should include an interval of many years, collective numbers, and large groups of mankind.
It appears to me, that a great number of the fundamental principles, or of the primary orders of medical architecture, have not yet been established, neither in Pathology, to which this Dissertation is chiefly related; and much less in Therapeuticks. The lumber and mountain of ponderous systems, heaped together from Galen to Stahl, can only be compared to Egyptian pyramids. Except what has been done by a few authors, hereafter to be mentioned, the sciences of Medical Arithmetick and Universal Prognosticks, are new in medicine. In emergencies, the constant appeal has been, with oracular reverence, to aphorisms and opinions of individuals. In a word, no medical author has yet attempted to take the gages of life and death, and of morbid devastation, and, in one general survey, to encircle the horizon of human existence and distempers. I have made some, at least laborious efforts, to rescue a momentous part of active medicine from that conjectural stigma with which the whole profession has been branded in the lump. And, however it may be slighted as an heretical innovation, I would strenuously recommend Medical Arithmetick, as a guide and compass through the labyrinth of Therapeuticks.
We are now to view the human race unexpectedly arrested, and struggling in the tragical and last stages of their terrestrial pilgrimage. The vision of human life is soon at an end: we are ushered into the world with lamentable exclamation; and are too often torn out of it in pain and agony. Bills of Mortality, however defective and inaccurate, yet sufficiently demonstrate this awful truth, that very few of the human species die of old age, or natural decay: by far the greater proportion are prematurely cut off by diseases. Of all the animal tribe, who usually bring forth one at a birth, none die in such numbers, in infancy, as the human race. In London, Vienna, Berlin, and every other overgrown metropolis of Europe, on an average, one half of the children born, die under three years of age. But in country towns and villages, the proportion of infant mortality greatly abates. In some country towns of England, of considerable magnitude and population, as Manchester, half the children die under five; at Norwich, half under six; at Northampton, half under ten years of age. London, therefore, will have lost, out of equal capitals, a number in the intermediate space, between three and ten, more than Northampton.
Attend next to the small proportion of Infant Mortality in open country districts. By Dr. Short’s registers of several small country villages in England, the major part born live to 25, 27, 33, and 40. In many healthy country parishes, half the inhabitants born live to mature age; to 40, 46, and a few even to 50 and 60; and rear large families of children. In some extensive country districts of Switzerland, similar observations have been made by Susmilch and Muret. Here, therefore, is an astonishing disparity between the duration of city and country life: but particularly, let it be engraved upon the memory, in the early stages of puerile exigence. Infants in cities resemble tender delicate plants excluded from fresh air; or fish confined in stagnant putrid water: they perish before acquiring a solidity and seasoning to endure the adulterated quality of the surrounding element; and their thread of life is then suspended by a tender cobweb.
Mortality, universally, during the first year after birth, is the most enormous in the funeral catalogue. A London infant at birth, has but an equal chance of living to three years old; whereas in the country, as before observed, half born survive to maturity. Upon reaching the third year, in cities, infants are somewhat seasoned, and the hurricane of puerile carnage is greatly abated. There is not afterwards such a prodigious disproportion between city and country mortality; and, in a few years after, from seven to ten, they approach nearer to an equality. From the London registers of burials, it appears that more die in the metropolis under two years of age, than from two to upwards of forty; and more under five years of age, than from five to between fifty and sixty: yet under five, there are but an inconsiderable number alive, compared to the latter class above that age: the deaths are greatly disproportioned to the living numbers or capitals. A few more die in the short interval between five and ten years of age, than in the succeeding double interval from ten to twenty. Between eight and sixteen years of age, one of every seventy of the Christ School boys is computed to die. Davenant rates the decrement in these years at only one per cent. After reaching the tenth year, the torrent of mortality in city, town, and country, is subsided; and during the next eight or ten years of adolescence, very few die. From seven to ten, may be termed the highest pinnacle: having surmounted all the dangers and precipices of the early preceding journey, there is no stage wherein the future prospects of existence and longevity are so extensive. From birth to ten, the tide of life continues in annual gradation to increase; and from ten to the ultimate verge of existence, vitality continues gradually to ebb. Between twenty and thirty, more die in London than in the fifteen preceding years; and the burial list continues turgid to sixty; at which latter stage, the mortality is computed between four and five per cent.
One reason, but not the only one, as I shall hereafter prove, of the great surge in the London bills, from twenty up to forty, is, that within this interval of life, the majority of the new settlers or recruits, arrive; and consequently augment the burials, from twenty to forty, beyond their natural proportion. After passing the meridian, and in the evening of life, the seasoned inhabitants of cities are said by Dr. Price, to have the advantage of the country, in health and longevity: that is to say, although the number who have survived in the country to sixty, seventy, and eighty, are greater proportionally than in cities, yet the latter class arrived at those years in London, have, comparatively, surer expectations of life. I do not, however, find this assertion verified in fact; the balance, if any, vibrating alternately on each side. The proportion of inhabitants who reach eighty years of age are computed, in London and Vienna, at one of every forty: but in country parishes, at one of every twenty-two; and in some, even one of every eleven. In both city and country, the few survivors at ninety, out of each thousand cœtaneous births, will have lost almost all their fellow-travellers in the journey, long before reaching that goal; and about three or four only out of each thousand, on an average, will be then left alive.
There are a few instances of extraordinary Longevity, to 150 and 165; such are Jenkins and Par, in this island. In Bacon Lord Verulam’s History of Long Livers, male and female; their climate, diet, mode of life, appetites, exercises, studies, passions, dispositions, habits, and complexions, were exceedingly dissimilar. It is however probable, from observation and analogy, that the indigent and laborious class of mankind do not attain to longevity in the same proportion with the middling and more opulent ranks. The wandering Savages of America are notoriously short-lived. Throughout Europe, Asia, Africa, and America, the rich, the poor, the inhabitants of city and country, with very different complexion, climate, soil, diet, and conveniences, all seldom exceed the usual term of life allotted to man: seventy and eighty is mentioned in holy writ, as the brink of our earthly duration. Since the days of Moses; that is, between three and four thousand years, human existence has been circumscribed within the same narrow bounds. In the London registers of mortality, during a period of thirty years, from 1728 to 1758, the total mortality is 750,332; and of all this number, 242 only reached beyond 100 years of age; one of whom arrived at 138. In some races and families of men, longevity seems to be hereditary; and his age, though little more than a dream, exceeds that of all other living creatures, a few only excepted. Amongst the quadruped creation, the elephant surpasses man in longevity: amongst the birds, the Swan, and a few others, have survived upwards of a century. The age of fishes is determined with more ingenuity than certainty: some seem to rival man in years. Among the numerous vegetable tribes, the Oak, Chestnut, and some other great trees, survive centuries.
On contrasting the mortality of Males and Females, it appears, that, notwithstanding the surplus of male births, the perils of childbearing, the many vexatious diseases peculiar to the fair sex, and that physicians and apothecaries have many more patients of the latter; yet the total aggregate number of living females exceeds that of males, in most European kingdoms. Upon a numerical inquest in Edinburgh, and some other great cities, it was found, that females were to males as 4 to 3: in London, as 13 to 10; and in some other cities and towns, as 9 to 8. But in country districts, Graunt and Susmilch agree, that the two sexes approach nearer to an equality. In the province of Jersey, in North America, the males were found the majority. From 1702 to 1752; that is, during a period of fifty years, I find the proportion of male and female mortality in London as follows: Male deaths, 618,076; Female deaths, 626,692. Whence, therefore, does it happen, that female deaths preponderate over the male, when more of the latter are born, and, as calculators assert, the mortality of males, at all ages, is greater than that of females? As a solution of this difficulty and partial exception, I should suggest a greater exportation and transportation of males to the sea and land service, to nautical commerce, and to unhealthy climates.
Even in the Marriage State, the chance of survivorship seems considerably in favour of the wife. In Breslaw, during eight years, five married men died to three married women. Susmilch, on a scrutiny through several kingdoms and principalities of Germany, found, that three married men died to two married women. Dr. Price estimates the chance in favour of the wife being the survivor in marriage, as 3 to 2: and this calculation is confirmed by the experience of the general Clerical Society in Scotland, who have long established funds to support their widows. From their records, it appears that twenty married clergymen have died to twelve wives; or, as 5 to 3. By an accurate survey of several principalities and cities in Germany, and collected by Susmilch, the widows were to the widowers as 3, and even 4 to 1. At marriage, it should be observed, there is generally a disparity of age; the bridegroom is from six to twelve years older than the bride; and therefore should, in the course of nature, die sooner: and perhaps also more widowers, comparatively with the other sex, enter into a second marriage; which tends to reduce their numbers. Besides, husbands are more exposed to the vicissitudes of the weather and seasons, to excessive labour and noxious trades, and to many other causes of diseases. Dr. Price finds, that the sexes respectively commence to be widowers and widows about 52 and 44; that is, men and women entering into matrimony, on a general average, at the age of 33 and 25, will become widowers and widows at 52 and 44: consequently, that each marriage will be dissolved by the death of one of them, in nineteen years; which is the ultimate term and probability of the husband and wife being both alive. For although some marriages may be protracted forty and fifty years, yet others may be dissolved in one year, or in a shorter time.
We have not yet sufficient information to determine the comparative chances of Female Longevity in the married and single state. At Berlin, indeed, calculators have remarked, that there were more married women alive at great ages, than of those who remained single. But such result might naturally be expected from a greater proportion in the decline of life of widows and wives, compared to antiquated virgins. From the ages of fifteen to twenty-five, married women likewise are said to have the advantage of the single, in whom the dictates of nature are frustrated and violated.