Kitabı oku: «The Mirror of Literature, Amusement, and Instruction. Volume 17, No. 471, January 15, 1831», sayfa 6

THE NATURALIST

RAINING TREES

(By John Murray, Esq. F.S.A. &c.)

The secretions of trees form a curious part of their physiology, but the influence of vegetation on the atmosphere seems to have been entirely overlooked, at least as far as it regards its meteorology.

In the case of that curious genus of plants the Sarracènia, in which the S. adúnca is most conspicuous, the foliaceous pouch is a mere reservoir, or cistern, to catch and retain the falling dew or rain. In the Nepénthes distillatòria, or pitcher plant, the case is different; and analysis proves it to be an evident secretion from the plant itself, independent altogether of the fact that it is found in the pitcher before the lid has yet opened. I may here state, en passant, that the results, I obtained from a chemical examination of this liquid differ materially from those of Dr. Edward Turner. The Córnus máscula is very remarkable for the amount of fluid matter which evolves from its leaves, and the willow and poplar, when grouped more especially, exhibit the phenomenon in the form of a gentle shower. Prince Maximilian, in his Travels in the Brazils, informs us that the natives in these districts are well acquainted with the peculiar property of those hollow leaves that act as recipients of the condensed vapours of the atmosphere; and, doubtless, these are sources where many tropical animals, as well as the wandering savage, sate their thirst "in a weary land." The Tillándsia exhibits a watery feature of a different complexion: here the entire interior is charged with such a supply of liquid, that, when cut, it affords a copious and refreshing beverage to man. That these extraordinary sources of "living springs of water" are not unknown to inferior creation, is a fact interestingly confirmed to us in the happy incidents detailed by Mr. Campbell, in his Travels in South Africa, where a species of mouse is described to us, as storing up supplies of water contained in the berries of particular plants; and, in Ceylon, animals of the Símia tribe are said to be well acquainted with the Nepénthes distillatòria, and to have frequent recourse to its pitcher. The mechanism of the "rose of Jericho" (Anastática hierochuntìna] shows the susceptibility of plants to moisture in a very remarkable manner; and I have submitted some experiments made with this extraordinary exotic, the inhabitant of an arid sandy soil, to the Horticultural Society of London. That succulents should be found clothing in patches the surface of the burning desert is a phenomenon not the least wonderful in the geographical history of vegetation.

In Cockburn's Voyages we find an interesting account of a tree in South America, which yielded a plentiful supply of water by a kind of distillatory process: this tree was met with near the mountainous district of Vera Paz. The party were attracted to it from a distance, the ground appearing wet around it; and the peculiarity was the more striking, as no rain had fallen for six months previous. "At last," says he, "to our great astonishment, as well as joy, we saw water dropping, or, as it were, distilling fast from the end of every leaf of this wonderful tree; at least it was so with us, who had been labouring four days through extreme heat without receiving the least moisture, and were now almost expiring for want of it." The testimony of travellers is too often enshrined among the fabulous; and their credentials either altogether rejected by some, or at least received "cum grano salis." Bruce of Kinnaird forms the most remarkable example of this kind, and the caricature of Baron Munchausen consigned the whole to sarcasm and ridicule; and yet the time is come when the more remarkable circumstances and phenomena mentioned by this traveller, verified by Lord Valentia, Mr. Salt, &c. are received as well accredited facts. The curious phenomenon mentioned by Cockburn finds an interesting and beautiful counterpart in two plants—namely, the Cálla Aethiópica and Agapánthus umbellàtus, in both of which, after a copious watering, the water will be seen to drop from the tips of the leaves; a phenomenon, as far as I know, not hitherto recorded.

The great rivers of the continent of Europe have their source of supply in the glaciers; but many of the rivers in the New World owe their origin to the extensive forests of America, and their destruction might dry up many a rivulet, and thus again convert the luxuriant valley into an arid and sterile waste; carried farther, the principle extends to the great features of the globe. What the glaciers effect among the higher regions of the Alps, the Pìnus Cémbra. and Lárix commùnis accomplish at lower elevations; and many a mountain rivulet owes its existence to their influence. It rains often in the woodlands when it rains no where else; and it is thus that trees and woods modify the hygrometric character of a country; and I doubt not but, by a judicious disposal of trees of particular kinds, many lands now parched up with drought—as, for example, in some of the Leeward Islands—might be reclaimed from that sterility to which they are unhappily doomed.

In Glass' History of the Canary Islands we have the description of a peculiar tree in the Island of Hierro, which is the means of supplying the inhabitants, man as well as inferior animals, with water; an island which, but for this marvellous adjunct, would be uninhabitable and abandoned. The tree is called Til by the people of the island, and has attached to it the epithet garse, or sacred. It is situated on the top of a rock, terminating the district called Tigulatre, which leads from the shore. A cloud of vapour, which seems to rise from the sea, is impelled towards it; and being condensed by the foliage of the tree, the rain falls into a large tank, from which it is measured out by individuals set apart for that purpose by the authorities of the island.

In confirmation of a circumstance primâ facie so incredible, I have here to record a phenomenon, witnessed by myself, equally extraordinary. I had frequently observed, in avenues of trees, that the entire ground engrossed by their shady foliage was completely saturated with moisture; and that during the prevalence of a fog, when the ground without their pale was completely parched, the wet which fell from their branches more resembled a gentle shower than anything else; and in investigating the phenomenon which I am disposed to consider entirely electrical, I think the elm exhibits this feature more remarkably than any other tree of the forest. I never, however, was more astonished than I was in the month of September last, on witnessing a very striking example of this description. I had taken an early walk, on the road leading from Stafford to Lichfield: a dense fog prevailed, but the road was dry and dusty, while it was quite otherwise with the line of a few Lombardy poplars; for from them it rained so plentifully, and so fast, that any one of them might have been used as an admirable shower bath, and the constant stream of water supplied by the aggregate would (had it been directed into a proper channel) have been found quite sufficient to turn an ordinary mill.—Mag. Nat. Hist.

THE GATHERER

 
A snapper of unconsidered trifles.
 

SHAKSPEARE.

HUMAN TIMEPIECE

J.D. Chevalley, a native of Switzerland, has arrived at an astonishing degree of perfection in reckoning time by an internal movement. In his youth he was accustomed to pay great attention to the ringing of bells and vibrations of pendulums, and by degrees he acquired the power of continuing a succession of intervals exactly equal to those which the vibrations or sounds produced.—Being on board a vessel, on the Lake of Geneva, he engaged to indicate to the crowd about him the lapse of a quarter of an hour, or as many minutes and seconds as any one chose to name, and this during a conversation the most diversified with those standing by; and farther, to indicate by the voice the moment when the hand passed over the quarter minutes, or half minutes, or any other sub-division previously stipulated, during the whole course of the experiment. This he did without mistake, notwithstanding the exertions of those about him to distract his attention, and clapped his hands at the conclusion of the time fixed. His own account of it is thus given:—"I have acquired, by imitation, labour, and patience, a movement which neither thoughts, nor labour, nor any thing can stop: it is similar to that of a pendulum, which at each motion of going and returning gives me the space of three seconds, so that twenty of them make a minute—and these I add to others continually."