Individual life exists on such conditions that it may at any moment cease; and the vital tenure varies not only with every change of external circumstances, but by natural laws at every year of age. It is most insecure in infancy and old age. At the age of puberty—before the period when the growth of the body is most rapid—before the age of its greatest strength—before the age of greatest intellectual power—it is less assailable by death. The chance of living through a given year increases from birth to the age of 14 or 15; it decreases to the age of 55-8 at a slightly accelerating rate; after which the vitality declines at a much more rapid rate.
Age of the People.
It is worthy of remark that the very aged have not in the ten years [1851-1861] increased in near the same proportion as the general population. In 1851 there were in England 107,041 persons who had passed the limit of “14 years;” in 1861 the number had only increased to 113,250. In 1851 215 persons were returned as being above 100 years old, but only 201 persons in 1861—one in every 100,000. Of this last number 146 were women, and but 55 men—nearly three women to one man. Only 26 had never been married. About a third were found living in large towns—21 in London, 11 in Liverpool, five in Manchester, one in Birmingham, four in Bristol, one in Leeds. As in 1851, so in 1861, these very aged persons were not found so often in the midland districts of the kingdom as in the north and the east, and most of all in the west. At the last Census, Norfolk had among its 435,000 people 11 above 100 years old; Gloucestershire, with 485,000 people, had eight centenarians; and Somerset, with its 445,000, had nine. Wales, with its 1,112,000, had no less than 24, the same number as Lancashire with its 2,400,000 people, and more than London with its 2,800,000 inhabitants. So far as the occupations of these long-lived persons are given, the returns show a majority engaged in pursuits that caused them to be much in the open air. Three had been farmers, 13 out-door farm servants, five labourers, three hawkers, three seamen, three soldiers; there was a fisherman, a quarrier, a waterworks man, a miller. But there was also a scrivener, four shoemakers, a baker, a grocer, a carpenter, a marine-store dealer, three persons occupied in cotton manufacture, two in woollen, one in silk, one in lace. Of the women the returns commonly state only whether the person is wife or widow, but we are told that there were six who had been domestic servants, two nurses, three charwomen, two washerwomen, and a gipsy. One centenarian was a member of the Household. Fourteen are described as land or house proprietors, or independent; 19 were passing their last years in the workhouse. Six were blind.—From the Census Report.
The Human Heart.
If we regard the construction of the blood-vessels, and other parts of the circulating system, we find that they are constructed entirely on physical laws. The Heart is the mover which propels the blood, and, after having given the stroke, its fibres become relaxed, to receive a fresh supply. In this case it is important that the fluid should not again regurgitate into its cavities; and to prevent that, a system of valves, not thicker than paper, has been contrived. Here we see a design identical with that pursued by man in the construction of his pump, or even, in some cases, of his floodgates. The only difference between the work of man and the work of Nature is, that the latter is executed in a manner so superior, that man feels that he sinks into insignificance beside the Creator.
That wonderful machine, the Heart, goes night and day, for eighty years together, at the rate of 100,000 strokes for every twenty-four hours, having at every stroke a great resistance to overcome. Now, each ventricle will contain at least one ounce of blood; the heart contracts 4000 times in an hour, from which it follows that there pass through the heart every hour 4000 ounces, or 350 pounds of blood. The whole mass of blood is said to be about twenty-five pounds; so that a quantity equal to the whole mass of blood passes through the heart fourteen times in one hour, which is about once in every four minutes.
The Sense of Hearing.
Mr. John Marshall, in a Lecture on the special organs of the Sense of Hearing, describes the wonderful arrangements for the protection of these organs and their adaptation to their office; the examination of their relative duties, in distinguishing the kinds and intensities of the sounds of such exceeding variety, produced by inanimate nature, by animals, and by art (music). For the appreciation of the pitch and quality of sounds Mr. Marshall considers that we are indebted to the delicate fibrous structure of the cochlea; for the knowledge of the intensity of sound to the tympanum or drum, which, possessing the power of tension and relaxation, thus acts a protective part; while in our knowledge of the distance and direction of sound we are guided by the external parts of the ear and by our experience.
Care of the Teeth.
Dr. J. H. Bowditch, of the United States, having examined with a microscope the matter deposited on the teeth and gums of more than 40 individuals, selected from all classes of society, and in nearly every variety of bodily condition, has discovered, in nearly every case, animal and vegetable parasites in great numbers; in fact, the only persons whose mouths were found to be entirely free from these parasites cleaned their teeth four times daily, using soap once. Among the agents applied, it was found that tobacco-juice and smoke did not impair the vitality of the parasites; nor did the chlorine tooth-wash, pulverized bark, soda, ammonia, &c. Soap, however—pure white soap—destroyed the parasites instantly, and is, therefore, the best specific for cleaning the teeth.