Bertha's Visit to Her Uncle in England; vol. 2 [of 3]

by Mrs. Marcet

I am quite disappointed at Mr. Scouler’s not mentioning the myrtle trees described in Anson’s Voyage, that tall wood of myrtles that screened the lawn where the commodore had pitched his tent; and which, sweeping round it, in the form of a theatre, extended up to the rising ground. I should like to have known what species of myrtle produced timber of forty feet in length. But above all, I felt disappointed at his account of the cavern; I was thinking of Alexander Selkirk, and could not help hoping that it was to prove the very one in which he had lived; or perhaps that some other romantic Selkirk was then its solitary master, instead of those Chilian cattle-killers.

29th.—There was a long conversation to-day on corals, corallines, and particularly on the formation of islands of that substance, which seems to take place so rapidly in some parts of the world.

Mr. Salt, the traveller, says that the islands in the Bay of Amphila are composed entirely of marine remains, strongly cemented together, and now forming solid masses; the surface of which is covered by only a thin layer of soil. These marine remains are chiefly corallines, madrepores, and a great variety of sea-shells, of species still existing in the Red Sea. Some of the islands are thirty feet above high-water mark; a circumstance which, he says, makes it difficult to account for the process of their formation. When a pillar of coral rises to the surface of the sea, birds, of course, resort to it; the decay of fish-bones, and other remains of their food in time produces a soil, which is followed by vegetation, and then it quickly assumes the appearance of a little island, covered with a solid stratum of earth. But in the present case, large pieces of madrepore are found, disposed in regular layers, far above the sea; and for this no satisfactory reason can be assigned, he says, except that the sea must have retired since they were so deposited; for this tribe of animals cannot work in the air.

There is nothing more curious, my uncle observed, than the changes produced on the face of the globe by the operations of the coral worm, a little creature so small as to be scarcely visible. New islands, he says, produced by its means, are continually rising out of the sea, and old ones are becoming united to others, or to the continent. In reading about something else, I met with a singular instance of this, in the account of Saugor Island, and Edmonstone’s Isle, in the Bay of Bengal, Edmonstone’s Isle appeared so lately as 1818; it is already two miles long, and half a mile broad, and the channel between the two islands is so shallow, that, in a few years, they will probably be joined together. Vegetation had commenced immediately on the most central and elevated part; saltwort, with one or two other plants, had given it a verdant tint, and by daily binding the shifting sand, were contributing to form the basis of a more durable soil.

Coral was formerly thought to be a vegetable, and even the celebrated Tournefort considered it to be a marine moss; but it is now known to be the production of a race of animals, of which it seems as much a part as the shell is of the snail. Most of the islands in the South Sea are coral rocks covered with earth. My uncle says that late voyagers have asserted that the bays and harbours of many of these islands have been observed to be gradually closing up, by the progress of these extraordinary creatures; and that it may therefore be supposed that these separate islands will in time be connected, and actually become a continent!

He told us, that M. de Peysonnel, of Marseilles, was the first who proved by experiment the animal nature of the coral; and shewed, that those bodies which former naturalists had mistaken for flowers, were, in fact, the insects that inhabited the coral. When the branches were taken out of the water, these supposed flowers, which proceeded from a number of white points in the bark, withdrew and disappeared; and when the branch was restored to the water, they were again perceptible. The white specks he proved to be holes in the outer surface, or bark, and corresponding with a series of cavities within; and secondly, he shewed that from these holes a milky fluid issued, which was an animal juice, and must, therefore, have proceeded from an insect. By immersing coral in strong vinegar, he could dissolve the calcareous bark to a certain depth, so as to shew the tubular structure of the interior uninjured.

Carbonate of lime, my uncle says, is the principal part of the substance of the whole tribe of corals and corallines; but where these minute insects, or rather polypi, obtain that material, or how they can decompose such an extraordinary quantity of it from sea-water, is one of those secrets of nature which philosophers have not yet discovered, although it is constantly in operation, and on an immense scale.

31st.—Frederick read to us, this evening, some of De Capell Brooke’s travels; and I ran away with the book afterwards, to copy for you this account of the cataract of Trallhätta, in Norway, which must be a singular scene.

“The whole water of the Gotha tumbles with fearful roarings down the rocky declivities, and in its descent forms four principal falls, the perpendicular height of which, taken together, is 110 feet. Yet the navigation is not obstructed; for locks with sluices, like those on navigable canals, have been cut in the solid rock, with incredible pains and labour; through them, vessels can be lowered to the level of the river below the falls, preserving their course with ease; and affording a strong instance of the power and ingenuity of man.”

In conversing about Norway, my uncle said, he thought the ingenuity displayed by the Norwegian peasantry was surprising. Living remote from towns, and scattered among their mountains, they become independent of assistance. The same man is frequently his own tailor, shoemaker, and carpenter, and sometimes even his own clock and watch maker. Most of them are very expert at carving, and the beautiful whiteness of their fir wood furnishes them with very pretty ornaments for their cottages. They work neatly in silver, brass, and other metals; and there are few things for the purchase of which they are obliged to have recourse to the distant towns.