the immediate causes of the decay of animal strength and life; and on a subject of so much importance to mankind, no source of information should remain unexplored, and no lights, however feeble, be disregarded. Naturalists, both of ancient and modern times, have considered the structure of plants as an inversion of that of animals; and have compared the roots to the intestines, and the leaves to the lungs, of animals; and the analogy between the vegetable sap and animal blood is very close and obvious. The experiments also, of which I have at different periods communicated accounts to you, supported by the facts previously ascertained by other naturalists, scarcely leave any reasonable grounds of doubt, that the sap of trees circulates, as far as is apparently necessary to, or consistent with, their state of existence and growth. The roots of trees, particularly those in coppices, which are felled at stated periods, continue so long to produce and feed a succession of branches, that no experiments were wanted to satisfy me, that it is not any defective action of the root, which oc casions the debility and diseases of old varieties of the apple and peartree; and, indeed, experience every where shows, that a young seedling-stock does not give the character of youth to the inserted bud or graft. I, however, procured plants from cuttings of some very old varieties of the apple, which readily emit roots; and these plants at the end of two years were grafted, about two inches above the ground, with a new and very luxuriant variety of the same species. These grafts grew very freely, and the roots themselves, at the end of four or five years, probably contained at least ten times as much alburnum, as they would have contained, had the trees remained ungrafted. The roots were also free from any appearance of disease or defect. Some crab-stocks were at the same time grafted with the goldenpippin, in a soil where the wood of that variety rarely lived more than two years and I again grafted annual shoots of the goldenpippin with cuttings of a young and healthy crab-tree, so as to include a portion of the wood of the golden-pippin between the roots and branches of the native and uncultivated species, or crab tree; and in this situation it grew just as well as the wood of the stock and branches. Some branches also of the golden pippin trees, which I mentioned in my former communication of 1795, being much cankered, were cut off a foot above the junction of the grafts to the stocks, and were regrafted with a new and healthy variety, Parts of the wood of the golden-pippin, in which were many cankered spots, were thus placed between the newly inserted graft, and the stocks; and these parts have subsequently become perfectly free from disease, and the wounds, previously made by canker, have been been wholly covered with new and healthy bark. These facts, therefore, satisfied me, that the debility, and diseases, of old varieties of fruits of this species did not originate in any defective action of the bark or alburnum, either of the roots or of the stem and branches, and my attention was consequently directed to the leaf, and succulent annual shoot. A few crab-stocks were grafted with the cuttings of the goldenpippin, in a situation and soil where I had previously ascertained, that the wood of the golden pippin rarely remained in health at the end of as econd year; and, as soon as the annual shoots had acquired sufficient growth and firmness, numerous buds of a new and luxurant variety of apple, which had recently sprung from seed, were inserted in them. During the succeeding winter, the natural buds of the golden-pippin branches were destroyed, and those inserted suffered alone to remain; and as soon as the leaves of these had unfolded, and entered on their office, every symptom of debility and disease disappeared in the bark and wood of the golden pippin: and each continued to perform its office, just as well as the wood and bark of the young seedling stocks could have done under similar circumstances. I made nearly the same experiments on the pear-tree, and with the same result. I have endeavoured, in several former communications, to prove, that the sap of plants circulates through their leaves, as the blood of animals circulates through their lungs; and I have not subsequently found any facts, in the writings of other naturalists, or in my own experiments, which militate against this conclusion. I have also observed, that grafted trees, of old and debilitated varieties of fruit, became most diseased in rich soils, and when grafted on stocks of the most vigorous growth; which had induced me to suspect, that in such cases more food is collected, and carried up into the plant, than its leaves can prepare and assimilate, and that the matter thus collected, which would have promoted the health and growth in a vigorous variety, accumulates, and degenerates disease in the extremities of the branches and annual shoots, while the lower part of the trunk and roots remain, generally, free from any apparent disease. I am, therefore, much disposed to attribute the diseases and debility of old age in trees to an inability to produce leaves, which can efficiently execute their natural office; and to some consequent imperfection in the circulating fluid. It is true, that the leaves are annually reproduced, and therefore aunually new but there is, I conceive, a very essential difference between the new leaves of an old and of a young variety; and, in support of this opinion, I shall observe, that the external character of the leaf of the same variety, at two, and at twenty years old, is very dissimilar; and it is therefore not improbable, that farther changes will have taken place at the end of two centuries.* * If these opinions be well founded, and the leaves of trees be analogous to the lungs of animals, is it very improbable, that the natural debility or old age of trees and of animals may originate from a similar source?—This is a question, upon which I am not by any means prepared to give an opinion; but, I believe, it will very generally be admitted, that the human subject is best formed for long life, when his chest is best formed to permit the lungs to move with most freedom. I have also long and attentively observed among our domesticated animals, that those individuals longest retain their health and strength, and best bear excessive labour and insufficient food, in which the chest is most deep and 'capacious, proportionately to the length of current the circulating fluid has to run; and the same remark will, I believe, be generally found applicable to the human species. I am, my dear sir, With great respect, sincerely yours, THO. AND. KNIGHT. Downton, Feb. 26, 1810. DISCOVERY OF THE MADEIRA ISLANDS. TO whatever degree of credit the romantic story of the discovery of Madeira, inserted in the preceding volume, is entitled, (and it is probably entitled to some,) the efficient discovery, or, at least, the colonization of that island, and of the other islands to which it gives a collective name, did not take place till a subsequent age, under the orders of the enterprising and enlightened Don Henry, Infant of Portugal. We call him enlightened, for so unquestionebly he was, though not upon the particular subject of religion; and though, through his religious bigotry, he became at once the explorer and the ravager of Africa, and the founder of the slave-trade! About the year 1418, a new expedition of discovery was fitted out for the express purpose of attempting to surmount the perils of Cape Bojador. In this expedition, Juan Gonzales Zarco and Tristan Van Texira, two naval officers of the household of Don Henry, volunteered their services, and, embarking in a vessel called a barcha,† steered for the tremendous cape. The Portu The leaf of a seedling apple or pear-tree, when the plant is very young, is generally almost wholly free from the pubescence, or down, which subsequently appears on its under surface, and which Bonnet and Mr. Mirbel have supposed to increase its surface and powers. But I feel little disposed to adopt this hypothesis, having observed, that the leaves of some new varieties of the apple, which have sprung from seeds of the Siberian crab, have both surfaces nearly equally smooth; and that these varieties grow faster, and bear heavier crops of very rich fruit, than any others, without being exhausted or injured. The barcha, a sort of brig with topsails, having all its yards on one long pole without sliding masts, as still used by tartans and settees. Barcha longa is a kind of small galley, with one mast and oars. Clarke, I. P. 153. gueze gueze were hitherto ingorant of the prevailing winds upon the coas of Africa, and the causes by which their influence is varied or increased. Near the land, and between the latitudes of 28° and 10° north, a fresh gale almost always blows from the N.E. Long sand-banks, which extend a great way out to sea, and which are extremely difficult to be distinguished in the mornings and evenings, and the prevailing currents, were powerful obstacles to the enterprize of these navigators. About six leagues off Cape Bojador, a most violent current continually dashes upon the breakers, which presented a most formidable obstacle to the brave but inexperienced mariners. Though their voyage was short, they encountered many dangers; and, before they could reach the cape, they were encountered by a heavy gale from the east, by which the billows of the Atlantic became too heavy to be resisted by their small vessel, and they were driven out to sea. On losing night of their accustomed head-lands, and being forced into the bondless ocean for the first time, the ship's company gave themselves up to despair; but, on the abatement of the tempest, they found themselves unexpectedly within view of an island, situated about 100 leagues west from the coast of Africa. With extreme joy, they beheld the coast of this island extending about twenty miles in length, to which they gave the name of Puerto Santo, because first discovered upon the feast of All Saints. This is the maller of the Madeiras, being about two miles broad; and, as the only roadstead is upon the south-west side, the Portugueze probably anchored upon that side, to be under the lee shelter of the island from the remnants of the tempest from which they had happily escaped. The island of Puerto Santo, or of the Holy Haven, is almost directly west from Cape Cantin; whence it would appear that these Portuguese navigators could hardly have passed much beyond Cape de Geer, when driven off the coast by this fortunate easterly tempest. Had they even advanced as far as Cape Non, they would almost certainly have been driven among the Canaries. It is perfectly obvious that they never even approached Cape Bojador in this voyage; unless we could suppose, that, after having been driven directly west from that cape, they shaped a northern course, after the subsidence of the tempest, and fell in with Puerto Santo while on their return to Portugal. Greatly pleased with the soil and climate of this island, and with the gentle manners of the natives, whom they described as in an intermediate state of civilization, and entirely destitute of any appearance of savage ferocity, Zarco and Vaz immediately returned to Portugal, where they made a report of the incident of their voyage; and, to confirm their opinion of the value of their discovery, they they requested permission from Don Henry to return for the purpose of establishing a settlement in Puerto Santo. By this discovery an advanced and favourable station was secured toward the south, whence any discoveries along the coast of Africa might. be prosecuted with greater ease and safety, and whence the dangers of the hitherto formidable Cape Bojador might be avoided, by keeping a southerly or S. W. course from Puerto Santo. From these considerations, Don Henry granted their request; and, yielding to the adventurous spirit which this accidental discovery had excited, he permitted several persons to join in a newly projected voyage, particularly Bartholomew Perestrello, a nobleman of his household. Three vessels were soon fitted out, which were placed under the respective commands of Zarco, Vaz, and Perestrello. These commanders had orders to colonize and cultivate the island just discovered, and were furnished with a considerable assortment of useful seeds and plants for that purpose. They happened likewise to take with them a female rabbit great with young, which littered during the voyage; and which, being let loose with her progeny, multiplied so rapidly, that, in two years, they became so numerous as to occasion serious injury to the early attempts at cultivation, and to baffle every hope of rendering Puerto Santo a place of refreshment for the Portugueze navagators; insomuch that a resolution was formed to abandon the young and rising settlement. After having landed the different animals and seeds which had been sent out by Don Henry, and seeing them properly distributed, Perestrello returned into Portugal to make a report to the prince, and Zarco and Vaz remained to superintend the infant colony. Soon after the departure of Perestrello, the attention of Zarco and Vaz was strongly excited by observing certain clouds or vapours at a great distance in the ocean, which continually presented the same aspect, and preserved exactly the same bearing from Puerto Santo, and at length occasioned a conjecture, that the appearance might proceed from land in that quarter. Gonsalvo and Vaz accordingly put to sea, and sailed towards the suspected land, and soon discovered that the appearances which had attracted their notice had actually proceeded from a considerable island, entirely overgrown with wood, to which, on that account, they gave the name of Madeira. After bestowing considerable attention upon the soil and other circumstances of this island, which was utterly destitute of inhabitants, Gonsalvo and Vaz returned to Portugal with the welcome intelligence, and gave so favourable a report of the extent, fertility, and salubrity of Madeira, that Don Henry determined to colonize and cultivate it. Accordingly, with the consent of the King of Portugal, the island of Madeira was be stowed |