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All the circumstances that are most essentially Recessary to life, may be comprised under the six following heads:

1. dir and Climate. It has long been known that fresh air is more immediately necessary to life than food; for a man may live two or three days without the latter, but not many minutes without the former. All climates almost give some instances of longevity; yet the majority of instances occur in cold and moderate climates. Heat relaxes and enfeebles, and the diet of hot countries is less nourishing than that of cold; while excesses are more generally indulged in.

2. Parentage. Being born of healthy parents, and exempted from hereditary disease, are circumstances evidently favourable to the duration of life: and numerous instances warrant the opinion, that longevity prevails in some families more than in others, or that descent from long-lived ancestors is one of the circumstances which give the great Latest probability of attaining to extreme old

3. Form and size of the individual. It is generally admitted, that persons of a compact shape, and of a moderate stature, are the most kely to live long. Tall persons frequently acquire a habit of stooping, which contracts the chest, and is a great impediment to free respiration; whereas the short-sized find little difficulty in keeping themselves erect, and are naturally much more active, by which the animal functions are retained in a state of greater perfection; the only disadvantage attending a short stature is, that it is frequently accompanied with corpulence, which is rather unfavourable to long life.

4. Disposition of Mind. Nothing is more conducive to longevity than to preserve equanimity and good spirits, and not to sink under the disappointments of life, to which all, but particularly the old, are necessarily subjected. This is a point which cannot be too much inculcated, as experience continually shows that many perish from despondency, who, if they had preserved their spirits and vigour of mind, might have survived many years longer. Neither the irritable, who are agitated by trifles, nor the melancholy, who magnify the evils of life, can expect to live long. Even those who suffer their strength and spirits to be exhausted by severe study, or other mental exertions, seldom reach great age. In the list before referred to, of 1712 persons who lived about a century, Fontenelle (who did not quite reach 100 years) is the only author of any Lote; and his great age is ascribed to the tranquil ease of his temper, and that liveliness of spirits for which he was much distinguished. Among those who have devoted themselves to the study or practice of music, a profession which encourages cheerfulness of mind, instances of great age have been very frequent.

5. Occupation. No person that leads an idle life will ever attain to great age; but health and long life must depend much on the manner in which the individual is employed. Those occupations are certainly the most conducive to the

duration of life, which are carried on in the open air, and require activity or labour; thus farmers, gardeners, and labourers in the country, are in general the longest lived. Foot soldiers also, who have survived the dangers of war, are remarkable for long life: they are generally stout and vigorous men, and the regu larity to which surviving soldiers must have accustomed themselves, whilst their careless and disorderly companions have dropped off, the erect posture to which they have been trained, and being of course men well formed by nature, and habituated to walk well (by which they enjoy the most natural exercise in perfection), all combine in their favour. Sailors also would furnish many instances of longevity if comfortably provided for in their old age: of this a striking proof is given in the accounts drawn up by Dr. Robertson, of the pensioners in Greenwich Hospital. In the year 1801, the complement of in-pensioners was 2410, of whom there were 96 of the age of 80 years and upwards; of this number 13 were above 90 years of age, and one man 102 years old. The number of out-pensioners was about 2500, of whom it appeared there were only 23 from 80 years of age and upwards. Of the former, therefore, about 4 in 100 survived 80 years of age, but of the latter not 1 in 100 attained that age, a sufficient evidence of the benefits of regularity and ease in the advanced period of life, and of the attention paid to the health of the in-pensioners at that excellent institution.

6. Mode of Living. If persons were to live with the simplicity of ancient times, it is proba ble that they would attain long life, without experiencing any material illness, merely by a proper attention to air, exercise, clothing, and diet. But in the present state of society, the great bulk of the community follow, not a natural, but an artificial mode of life, and thence are perpetually exposed to various temptations, which they find it difficult always to resist, and to dangers which they cannot always avoid. Most persons, however, have it in their power in some degree to regulate their manner of living by their own choice; and by a little attention to their food, clothing, employment, rest, and temper of mind, might not only contribute materially to the prolongation of their lives, but preserve themselves from many diseases, and greatly increase their relish for all the enjoyments of life.

The importance of wholesome food, for the preservation of health and promoting long life, and the avoiding of excess, whether in eating or drinking, is sufficiently obvious. Some instances, indeed, are recorded of persons who have continued to commit excesses, and have lived long; but these are to be considered in no other light than as exceptions to a general rule; and it may reasonably be contended, that if such persons lived to a great age, notwithstanding their intemperance, they would have lived much longer had they followed a different course. Experience will point out those articles of food which are best adapted to the constitution of each individual, and there cannot be a better rule than to adhere to them as far as circumstances will permit. It may be observed, however, that people in general, especially those who do not labour, eat much more than nature requires; that a little abstinence or self-denial may often be of use, either to prevent or to cure disease; and at

any rate, that none but hard working people, the young who are growing fast, or persons who are travelling about, should eat more than one full meal each day.

As to clothing, much must depend on situation and climate; but it is generally found a useful practice to wear woollens next the skin. It is remarked in many parts of Scotland, that since the use of flannel shirts has been given up by the lower orders, the rheumatism and other diseases formerly unknown, have become very frequent, and are daily increasing. In the West India islands, if care be taken to make the troops Wear flannel shirts, they are generally exempt from various disorders, which otherwise would probably have attacked them. Even the negroes themselves are said to prefer flannel to cotton or linen, and find it a much more comfortable and useful dress.

order to allow a sufficient surplus for the waste and expenditure of warfare: as though the Deity himself gave a sanction to the wrath and savage contests of man, by an express law of nature. The latter has been brought forward to prove a greater tenacity to life in the female than in the male form; and some physiologists have advanced so far as to conceive, that this greater tenacity to life in females exists not only through every stage after birth, but even before birth itself: in corroboration of which the tables of Mr. Kerseboom have been adverted to, which seem to determine that the still-born males, and those necessarily injured in birth, are as the still-born and injured females in the proportion of three to two. Now this reasoning is not only in diametrical opposition to the preceding, but in our opinion just as fallacious. As the subject, however, is of the highest importance, and nevertheless has scarcely been touched upon with a view of any fair elucidation, by any writer, we shall encroach upon an additional page, in order to harmonize the whole, and reduce

Exercise cannot be too much recommended; and as the inhabitants of large towns, and persons engaged in sedentary occupations, cannot take all the exercise abroad that may be necessary for their health, they ought as much as the various facts to one common and simple possible to accustom themselves to be walking about even in their own house, for though this practice does not make up for the want of exercise abroad, it is certainly the best substitute for it. Exercise is attended with the advantage of creating an inclination to retire early to rest, and of inducing sound sleep. Every one should take all the repose that nature requires, but should never continue long in bed without sleep. ing. Early rising, even if carried to ar. extreme, is far more conducive to health and long life, than late hours at night and slumbering in bed in the morning.

There is nothing that can tend more to long life, than for a person to obtain a complete command of his passions, and in particular to preserve his mind from being ruffled by the occur. rences of life. Perhaps there is no maxim more likely to promote good health, and consequently the duration of life, than that of paying a proper attention to temper, temperance, and sleep. By good temper the mind is preserved from disease; and by temperance, the body; and both the mind and the body, when exhausted, are again recruited and restored to their former strength, by a sufficient quantity of

repose.

Proportion of Males born to Females born. In contemplating the origin and duration of human life, there are two very striking facts, which hitherto remain altogether unaccounted for; and have, indeed, attracted less attention than they ought to do. The first is, that the birth of male children is considerably more numerous than that of female: upon the calculation of Derham, in the proportion of 14 to 13; a calculation which we cannot but regard as pretty correct, since it has more recently been confirmed by the observations of Muret, Susmilch, Dr. Price, and Dr. Haygarth. The second extraordinary fact, is, that notwithstanding this superiority of births in males, the number of living females is considerably greater than that of males, in an average proportion of the different stages of life. It has been said by some writers, to be so in every stage, but this we shall presently point out to be an

error.

These extraordinary facts seem, at first sight, to oppose each other. Mr. Derham, with more piety perhaps than judgment, ascribed the former of them to the provident care of the Deity, in

principle. In doing which, we shali first beg the reader's attention to the following extract, from a valuable, and we believe highly accurate table of average male and female life, upon a scale of 10,000, introduced by Mr. Baily, from the national tables of Sweden, into his "Doctrine of Life Annuities." Any other table of a similar kind would answer our purpose as well, but we take this as being one of the latest, and most immediately at hand.

Age.

MALES.

FEMALES.

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stap-l the test of a rational investigation. The fetus hence, then, originating, it was the opinion of the Grecian founder of this doctrine, and an opinion which is at least plausible, that the sexual distinction was stamped by the party evincing the greatest degree of orgasm during connexion; and as from the superior muscularity and salacity of man to that of woman, we have reason to conjecture that a somewhat greater portion of organ must usually be with the former, we have reason to conjecture even à priori, that the greater number of fetuses be of the male sex. This doctrine is thus elegently and accurately laid down by Lucretius, iv. 1202.

Et conmiscendo quòm semine forte virili
Femina vim vicit subitâ vi, conripuitque;
Tum similes matrum materno semine fiunt:
Ut patribus patrio.

We may hence give a probable guess, why, from Le common laws of nature, the male births should in some degree exceed the female.

But the principle which thus operates ab initio, should continue to operate in futuro, and the de form produced by a somewhat superior degree of vigour, should in general evince more Your through the different stages of life, be better able to ward off the dangers that threaten it, and of course (in opposition to the common exision upon this subject) discover a greater tenacity to life, under equal circumstances, than fmales

Now, this we believe they do; and we may safely appeal to the preceding table, in support of such an assertion. By this table, it will be found, that the average death of females for the second and third years, keeps nearly on a par with that of males, and upon the whole rather exceeds 忠 As boys, for the most part, now begin to be ore exposed to external air and external accidints than girls, the dangers hence derived make De number of deaths from this period greater eng the former than among the latter. And the same exposure to casualties continuing, the ane proportion of deaths still prevail, till the period of puberty; when, the change which takes place in the female form being of a more trying Character than what occurs in the male: the deaths are again reduced very nearly to a bakace. But majority being now acquired on beth sides, more males will again be found to fall victims than females, in given numbers and Even ages, from the more extensive range and car plexity of the casualties, to which males are

subject; and which produces an extra morty, more than sufficient to counterbalance that which takes place among females, from childbearing. As old age, however, supervenes, the male is again brought back to an equality of exemption from external casualties, from the faleness which prevents him from being any rger able to brave them; and here we again see 2 equality of deaths restored between the two; at the age of 70, the males' deaths out of 1541 being 120, and the females' deaths out of 1979 eg 130; while at 90, the former, out of 38 we 12, and the latter out of 58, are 15. If the ertion be true, that more still-born and injured le children are brought forth than female which, however, is by no means to be fully depened upon) it may possibly be accounted for yon the same principle. Generally speaking,

the weakliest women are those that are most deformed; and both the weakly and the deformed are those from whom we should rather expect male than female children, upon the hypothesis assumed above. If then the stoutest and most vigorous children be the males, such have the greatest chance of being injured in labour, as well from the superior delicacy, as the deformity of the mother, in consequence of the superiority of their size, and the greater difficulty in their passage into the world.

Upon the whole, man, as Haller has long since observed in his physiology, has no right to complain of the shortness of life. Throughout the whole of living beings, there are few who unite in a greater degree, all the internal causes which tend to prolong its different periods. The term of gestation is very considerable; the rudiments of the teeth are very late in unfolding; his growth is slow, and is not completed before about twenty years have elapsed. The age of puberty also is much later in man than in any other animal. In short, the parts of his body, being composed of a softer and more flexible substance, are not so soon hardened as those of inferior animals. Man, therefore, seems to receive at his birth the seeds of a long life: and if he reach not in general the distant period which nature appears to promise him, it is owing to accidental causes foreign to himself. Instead of saying that his life is completed, we ought rather to say that it was cut off.

In few words, the natural and total duration of life, whether of animals or vegetables, is in a considerable degree proportioned to the period of youth. A tree or a quadruped that soon acquires its full size, decays much sooner than another which continues to grow for a longer time.

Among plants, some

species of boletus, like

while

With

some species of insects, require only a few hours to unfold themselves, and as soon decay. Several fungi live only a few days, others a few weeks and months. Annual plants live three, four, or at the utmost eight months: biennial plants sixteen, eighteen, and even four-and-twenty months. Many herbaceous plants grow a few years only, but more long series of years: shrubs and trees in some instances live eight, ten, a hundred, or even a thousand years. us the oak and lime-tree attain the greatest longevity; but these are nothing to the longevity of the adansonia digitata, the pinus cedrus, or the general family of palms: the first of which, though its stem is usually not more than ten or twelve feet high, measures from 75 to 90 feet in circumference, sends off branches from its top in every direction, of from thirty to sixty feet in length; takes several centuries in acquiring perfection, and (according to the general computation) is a thousand years before it de

cays.

The same observation will more strictly apply to animals in general. Of man, we shall add nothing farther. The life of fishes we know but little of, from their existing in a different element than our own; yet we know, that while the salmon, which grows rapidly, takes only about six years to reach its full size, and seldom or never exceeds from twenty-four to thirty years in its life; the carp, which grows more tardily, and to almost any extent (having been occasionally found five feet long, and two hundred pounds in weight) has been fairly ascertained a century old,

and been scen, according to Mr. Reinhold Foster, in a group of from two to three hundred, at Cherlothenburg, a Prussian palace, the common age of which was from fifty to sixty years.

Among quadrupeds, the longest lived is the elephant; but this is also the quadruped that is longest in acquiring its full growth. Among birds, the swan requires forty-two days for its incubation; and the parrot forty; and these are the birds of the greatest longevity we are acquainted with. The crow or raven, the goose

and eagle, have also a reputation for great longevity; but it is a reputation founded on doubtful authority. We shall subjoin a table of the comparative ages of the most common quadrupeds and birds, together with the periods of their incubation or gestation, as a datum from which many naturalists, but perhaps erroneously, calculate. We take it from Tilloch's Philos. Mag. xii. 245, copied from Count Moronzo to C. Lacepede:

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Mortality of London." But the inquiry has, moreover, led to the creation of a distinct branch of analytical science,-that, we mean, which relates to the valuation of life annuities and assurances. See ASSURANCES and the article immediately following. LIFE ANNUITIES, are such periodical payments as depend on the continuance of some particular life or lives. They may be distinguished into an Buities that commence immediately, and such as commence at some future period, called reversionary life annuities.

The species of mathematical investigation which leads to the determination of life annuities and assurances, is perfectly modern, and in fact, may be called new: for we find scarcely any traces of it before the commencement of the last century. Van Hudden was the first who attempted the developement of a rational theory; and this was still further expanded by the celebrated pensionary John de Witt, in a tract printed at the Hague in 1671, under the title "De Vardye van de Lif-renten na Propertie van de Losrenten." Nothing, however, to which a reader of the present times could recur with advantage, was produced till 1692-3; when Dr. Halley, whose labours so greatly enriched almost every department of mathematical knowledge, gave, in the Philosophical Transactions, "An Estimate of the Degrees of Mortality of Mankind, drawn from curious tables of the births and funerals at the city of Breslaw; with an attempt to ascertain the price of annuities on lives." In this paper Dr. Halley presented a very perspicueus view of the principles on which an accurate theory of assurances and annuities must rest, and from the application of these principles to the Breslaw observations, deduced the first correct table of the value of life annuities. De Moivre took up the subject where Halley left it, and in 1724 published the first edition of his “Annuities on Lives." In this very ingenious and valuable work, he started the hypothesis that "the decrements of life are equal and uniform, from birth to the utmost extremity of human life;" an hypothesis which, though it much simplifies computation, and furnishes a very elegant theory, considered merely in relation to its analytical symmetry, and facility of practice, yet when applied to such cases as actually occur, often leads to results extremely erroneous, unless it be subjected to the checks furnished by other theories. In 1742 another excellent mathematician, Mr. T. Simpson of the Woolwich Academy, in a curious little treatise "On the Doctrine of Annuities and Reversions," clearly explained the method of computing the value of annuities, &c. from the real observations of life-an improvement certainly of great importance; and prosecuted the subject still farther in his "Select Exercises," published in 1752. In 1753 and 1755 Mr. James Dodson published the second and third volumes of his "Mathematical Repository," in which he has given the most extensive collection extant of problems purely algebraical, and solved an immense variety of questions relative to annuities, reversions, survivorships, and assurances; though, unfortunately, he has through out adopted the hypothesis of his friend M. de Movre.

The science remained in this state, without much improvement, till the publication of the first edition of Dr. Price's celebrated treatise, in 1769. This work, entitled Observations on Reversionary Payments, &c." was first published VOL. VII.

with a view to oppose and destroy the injurious effects and evil intentions of a class of men (unfortunately to be found in every stage of society) who, under pretence of establishing societies for the benefit of old age, and of widows, were only forming schemes to allure and to defeat the hopes of the ignorant and the distressed. His efforts were eventually crowned with success: and those bubble societies have long since met with the fate which he so truly predicted.

In this laudable pursuit, Dr. Price saw the necessity of more accurate observations on the mortality of human life, in order to determine with more correctness the value of life annuities, and to show more forcibly the futility and extravagance of the schemes that were issued by those societies. By the assistance of some public-spirited individuals, he obtained correct registers of the rates of mortality at Northampton, Norwich, Chester, and other places in England. But still, the computation of the values of annuities, according to these observations, was a work so tedious and unpleasant, that little hopes were entertained of profiting by those researches: and Dr. Price suffered three several editions of his treatise to pass over without affording any additional information on this subject. At length the fourth edition appeared (1783) enriched with several valuable tables of annuities on single and joint lives, at different rates of interest, deduced not only from the probabilities of living as ob served at Northampton, but also from the probabilities of living as observed in the kingdom of Sweden at large.

The great addition which Dr. Price has made to our means of information respecting this science, and the assiduity with which he thus promoted some of the best interests of mankind, deserves the highest commendation: and his labours on this subject entitle him to our warmest praise. The primary object which he had in view has been fully answered; and his treatise was admirably adapted to that end. In every other respect, however, it is far from being complete: and the reader will look in vain for the most common cases that occur in practice. Indeed, those subjects which are to be met with, do not readily present themselves; owing to the loose and irregular manner in which they are treated. Dr. Price's object was not so much to insert what was new, as to illustrate (by some striking examples) a few of the leading problems, with a view to oppose the pernicious schemes that disgraced the age in which he lived. But, those schemes having long since vanished, his observations may now be considered rather as a beacon to posterity.

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The next treatise on this subject is that by Mr. Morgan, entitled The Doctrine of Annuities and Assurances," which appeared in 1779. This author sets out with the vain attempt to render the principles of the science intelligible to persons unacquainted with mathematics: but, after a fruitless effort for this purpose, he ultimately leaves his readers to pursue their inquiries by the common and only useful method of analysis. Besides some valuable observations "on the dif ferent methods of determining the state of a society, whose business consists in making assurances on lives," that work will be found to contain a variety of problems, treated for the most part in a plain, easy, and familiar manner; and adapted to the state of the science at that period.

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