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islands comprise an area, altogether, of a hundred and eighteen thousand four hundred and sixty miles.* This space, multiplied by thirty, will amount to three millions five hundred and fifty-three thousand eight hundred square miles. Thus, for the comfortable support of seven hundred and twenty millions of the human race, like the inhabitants of our own country, no more than about three millions and a half of square miles of surface would be requisite. Now, in the four quarters of the globe, the whole of actual land surface which is presented to us, has been stated to be a little more than fifty-one millions of square miles, though some suppose it may be a little more; but, on either computation, we see that one-sixteenth or seventeenth part of our present dry land would be quite enough of cultivable ground to nourish, at one time, the greatest amount of human population which has hitherto been permitted to be, contemporaneously, upon the earth."

I stated in a former paper, that the kingdom of China alone might be cultivated to such extent as to support five times more inhabitants than the world at present contains. By another calculation, Mr. Turner has shown that, according to its present state of cultivation, defective as it is, twice its superficial area, or about two millions and a half of square miles, would maintain all the present inhabitants of the earth. But this would be only one-twentieth part of our present dry land. Thus one-sixteenth only of what is dry land, would be sufficient for all our existing population, living as our fellow countrymen do; or one-twentieth, living like the Chinese, under their respective soils and climates, and with that degree of cultivation which each country at present receives.

But a far less proportion of surface would suffice, under a more extended cultivation. The following calculation is made in a philosophical work of merit :-"The United Kingdom contains 74,000,000 of acres, of which

* England and Wales contain 57,960 square miles; Scotland, 30,500; and Ireland, 30,000; in all, 118,460 square miles.—Murray's Encyclopedia Geog. pp. 312-475.

† Sacred History, vol. iii. p. 401.

Half an acre,

.*

64,000,000 are susceptible of cultivation. with ordinary attention, yields corn enough for one individual, and one acre will feed a horse ;* hence the United Kingdom could maintain 120,000,000 of people, and also 4,000,000 of horses." By this statement, the whole present inhabitants of the earth might be supported on an area only between five and six times larger than that of Great Britain and Ireland.

There is, then, a very large proportion of our cultivable land still unoccupied. This, of course, results from the wise prospective arrangements of Providence. The plan adapted by Divine Wisdom is that of the progressive improvement and developement of the human species. According to this plan, a wide space was required to be left for future occupation, in proportion as our race shall improve and increase. Four thousand years have passed away, in which the system has existed. It has fulfilled, and is fulfilling, the purposes of its Creator. The scheme is still in progress. Improvement is proceeding in an accelerated ratio, and population keeps pace with improvement. Notwithstanding there has been a constant demand for more food, which has always been met by a new creation of supply, the means of subsistence are unexhausted, and, for several ages, inexhaustible.

Let us look, however, a little more minutely at the practical state of the question. For the last century, England has been making an unexampled progress in civilization, which has been accompanied with an equally remarkable progression in its population. Leaving out of the question America,‡ and other countries similarly

*This is independent of grass.

+ Edinburgh New Philosophical Journal, September, 1828.

·

Mr. Malthus, founding on the rate of increase in America, assumes, that the population will, under favorable circumstances, double itself every fifteen years; and Bishop Summer, whom I have quoted in the Spring' volume, in considering the origin of agricultural labor, adopts his premises. Mr. Sadler, however, has made a formidable attack on Mr. Malthus's principles, and, among other things, has shown that he made much too little allowance for the effects of emigration. At all events, the practical question is rather to be taken from the experience of an old than a new country. The possibility of a population doubling

situated, in which the inhabitants receive rapid increase by emigration, England may be taken as an example of the most favorable state of society for the advancement of its numbers, which is likely to occur.* It is now increasing its population at the rate of about one and a half per cent. yearly; and, within the last seventy years, the amount of inhabitants has been doubled. Assuming, therefore, this as the ratio of future increase over the whole surface of the globe, which is a liberal ground of estimate, and assuming, at the same time, that the whole improveable soil is eighteen times the quantity at present cultivated, it would require at least three centuries to people the whole globe, so as to exhaust the food capable of being raised at the rate of the present average produce of Great Britain. This, however, is but one element in the calculation; and we shall soon see that the Creator has bestowed other resources on Nature, which must throw such a consummation to a far greater, but, with our present data, an indefinable distance.

FOURTH WEEK-TUESDAY.

HUMAN FOOD.-PROVISION FOR THE FUTURE-IMPROVED CULTIVATION.

THE extent to which improvement may be carried in the art of agriculture it is not easy to estimate; but that

itself once in twenty-five, in fifteen, or even in ten years, may be true, and yet the natural and moral checks may be such as to render this possibility nothing better, practically considered, than a mere useless speculation.

* England is probably the most favorable example of increase in the population of any country of modern Europe. Scotland has increased in the same period so as to double its population only in one hundred and twenty years. Ireland, in 1791, had doubled its population during the preceding seventy-nine years. France, at its present rate of increase, would, according to Mr. Malthus, require one hundred and eleven years to double its population. If, indeed, the rate be taken from the experience of the last thirty years, it would take no fewer than two hundred years for a duplication.

it may be very great, no one can doubt who is acquainted with the history of society, and the present state of practical science. The progress which has hitherto been made in cultivation, has resulted chiefly from the experience acquired by unscientific men. The labors of the farmer have generally been carried on by persons in an inferior rank of life; or, at all events, by those whose minds were not turned to such objects as might enable them to conduct their plans on extended and enlightened views of the powers of Nature. The real value of agricultural improvement has, however, been, within the last half century, better understood, and men have begun to direct their attention more energetically to the investigation of its principles, and to the improvement of its operations. That much advantage may be derived from such a source may well be believed, both when we consider what science has effected for the other arts, and when we look at what it has already accomplished for agriculture itself. The prodigious advances which have been made in manufactures, by the genius of a Watt and an Arkwright, afford evidence of what may be effected in other departments, and rebuke the presumption of those who would set bounds to improvement. In the cultivation of the soil, the scientific labors of Sir Humphrey Davy, and the example he has set of the successful application of chemical knowledge to this useful art, is, in itself, an important step, which, in its future consequences, stretches far beyond the discoveries he has actually made, and opens an extensive and fertile field, hitherto but little explored. Who shall venture to say to what results such a direction of talent may eventually lead? We have acquired a more accurate analysis of the constituents of soil, and of the plants which it nourishes. Something is still wanted for the practical application of this knowledge; but it will not be thought chimerical to conjecture that we may be on the verge of some discovery which shall alter the whole system of agriculture, and give a new and incalculable force to the powers of vegetation.

The precise nature of the process, by which the simple elements derived from the soil are decomposed, and con

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verted into the proper juices of plants in their leaves, is still unknown; but that it is a strictly chemical elaboration is highly probable: and that it may be imitated by artificial combinations, notwithstanding the power essential to it, of the living principle, at present so mysterious, seems at least to be possible. "We have not yet discovered," says Mr. Turner, " the art of converting azote, carbon, oxygen, and hydrogen, lime, or clay, or silex into nutritive matter. The vegetable principle, universally, has the power of effecting this, by its diversified organization, into its own compounded substance; and this, so made, becomes our food. Whether mankind, who now, by Mr. Crosse's experiments, have attained the power of crystallizing matter into gems, and of reviving insects or infusoria by the aerial electricity, will acquire the knowledge how to imitate the vegetable process; and, like this, to put the material particles of our surface into an alimentary condition for our use, no one now living can either affirm or deny. It is not more unlikely, than the galvanic metallization of the earths and alkalis, or the crystallizations of Mr. Crosse, before the last year, 1836."*

* Sacred History of the World, vol. iii. Letter 30. The experiments by which Mr. Crosse seems to have produced insects from silex, have justly attracted the attention of the philosophical world. It is no wonder that his facts, whilst they cannot be doubted, should have excited the desire to explain them away, they are so new in themselves, and seem so directly to imply the exploded doctrine of equivocal generation. It appears, as yet, too soon to pronounce dogmatically on this interesting subject. The account which Mr. Crosse himself has given of their appearance, is very singular. It is in substance as follows:-"To a portion of the silicate of potassa, formed by a process which he has described, boiling water was added, to dilute it, and then, slowly to supersaturation, hydrochloric acid. This fluid was subjected to a long-continued electric action, through the intervention of a porous stone, in order that, if possible, crystals of silica might be formed at one of the poles of the battery; but Mr. Crosse failed in accomplishing this by these means. On the fourteenth morning from the commencement of the experiment, were observed, through a lens, a few small whitish excrescences or nipples, projecting from about the middle of the electrified stone, and nearly under the dropping of the fluid above. On the eighteenth day these projections were enlarged, and seven or eight filaments, each of them larger than the excrescence from which it grew, made their appearance on each of

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