emigrate annually to other countries; for according to Professor Rau, it doubles every 28.6 years; in England, every 42-3 years; in Spain, every 419 years; in Prussia on the Rhine, every 52-33 years; in Austria, every 53'6 years; in France, every 110.3 years; in Sweden, every 118; and according to M. Ch. Dupin, every 66 years in Russia. (Quetelet, Op. Cit. p. 51.)

It may be received as a fundamental axiom, that whatever is most delightful to the unperverted instincts of mankind, is most favourable to health, beauty, longevity, the developement of all the higher faculties, and the perfection of human nature,—such for example, as a medium temperature, pure air and water, simple but nourishing food, moderate exercise of the physical, intellectual, and moral faculties, especially of the domestic and social affections, and tranquillity of mind, which is the fruit of a well spent life.* Nor is it less certain, that whatever excites painful or disagreeable sensations, is detrimental to sound will advance in literature, science, and the arts, with a rapidity proportioned to the physical superiority of its inhabitants. From all the foregoing facts and observations, it is evident that the climate of Europe is superior to that of all the other quarters of the Globe, and that of the United States next,-if we except New Zealand and a few other small islands.

* But it is stated by Sir John Sinclair in his Code of Health, that after many years of research, he had not been able to find one case of an habitually wicked man who had arrived at a great age. The truth is, that the natural tendency to crime is in itself a fatal disease, and should be treated as such.

health and long life, whether it be excessive heat or cold, too much or too little nourishment, excessive study, immoderate indulgence of the passions, impure air, the depressing emotions, nauseous drugs, or intemperance in the use of spirituous liquors.

From the researches of Dr. Madden, contained in his work entitled "Infirmities of Genius," it would appear, that notwithstanding excessive intellectual exertion is a frequent cause of ill health and premature death, the mean duration of life among the learned and liberal professions, is about 46 years, if we deduct 30 per cent. for the mortality of infancy. For he found that by taking twenty individuals belonging to each of the professions devoted to science, literature, and the arts, in different parts of Europe, the was as follows:

Writers on Natural Philosophy....
Moral Philosophy

average

74.7 years.

70.8

given by Quetelet, theologians live longer in Prussia than any other class; agriculturists next; and physicians the shortest period of all. More extended observations are required to furnish data for a sure induction.

According to the reports of Tulloch, life is longer among officers of the British army in the West Indies, than among privates, in the ratio of 7.8 per cent. to 42; while the mortality increases from the age of eighteen to forty and upwards. And we learn from the late report of Mr. Chadwick, on the sanatory condition of the labouring population in England and Wales, that the average value of life among the nobility and gentry, varies from forty to fifty-seven years,-among the trades people, from twenty-seven to forty-one-while among labourers and mechanics, it is from fifteen to twenty-five years,—that above 50 per cent. of all the children belonging to the labouring classes die under five years of age; whereas the ratio is only 25 per cent. among the gentry. The fatal influence of destitution would appear from the fact, that out of 12,313 individuals of all ages, in the English workhouses, 2552 deaths occurred in 1838, or about 20 per cent. of the whole. (Lancet, May 1, 1841.) But even in the hospitals and infirmaries of England, the mean annual mortality varies from 4 to 11 per cent. according to Porter's Progress of the Nation.

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CHAPTER III.

Influence of Climate and Season in modifying the
Diseases of Mankind.

"The time may come when, guided by yet undiscovered knowledge, new and more direct principles, the tendency to tubercular and other morbid formations, may be surely checked, chronic inflammations cured, and fever suspended in its first movements."

CONOLLY.

A COMPLETE history of the mode in which the diseases and mortality of the human race are modified by external temperature, regimen, clothing, habitations, employments, and the various modes of living, would afford more practical information in regard to the causes, prevention, and right method of treatment, than all the systems that have been invented within the last two thousand years; for it would enable us to reduce the heterogeneous and chaotic mass of facts that constitute the sum of Medical Literature, to the certainty of an exact science. And that such an important undertaking might be, to a great extent, accomplished in a short time, by the combined exertions of a few enlightened individuals, is manifest from what has been recently done in

Great Britain by the Reports of Major Tulloch, and those of the Registrar General, aided by the judicious researches of Mr. Farr and other statisticians.

The diseases of man are no less modified by climate and season, than the various mechanical, chemical, and physiological operations of our planet,-being as different in the tropical portions of Africa, India, South America, and the West Indies, from what they are in the temperate and higher latitudes, as are the botanical and zoological characters of those regions.

The following tables, constructed from the Reports of Tulloch, laid before both Houses of Parliament, exhibit the average annual ratio of mortality per 1000 mean strength of the British troops serving in different parts of the world, from 1817 to 1836, omitting epidemic cholera.