Part 55
Sir Hans Sloane, in his account of the bogs of Ireland, published in the “Philosophical Transactions,” notices a curious fact, namely, that when the turf-diggers, after having dug out the earth proper to make turf or peat, reached the bottom, so as to come to the clayey or other soil, by draining off the water, they met with the roots of fir-trees, with their stumps standing upright, and their branches spread out on every side horizontally. This was evidently the place of the growth of these trees, the branches of the roots of which are in some parts matted, as is seen in the roots of trees closely planted. Large pieces of wood have been found, not only in clay-pits, but likewise in quarries or stone-pits, in the blocks of stone raised out of their strata or layers. The black spongy mold employed for peat smells strongly of bitumen, or petroleum, a great proportion of the oil of which is yielded by distillation; so that, singular as it may appear, not only oil, but a material which may be used for candles, may be extracted from these peat-bogs in large quantities; and it has even been proposed that this business should be carried on on a large scale, with a view to giving prosperity to the country. In several parts of Ireland a singular phenomenon has been observed: on horses trampling with their feet on a space of soft ground, a sudden appearance of light ensued. On the mold, which agreed in color, lightness, &c., with peat earth, being examined with a microscope, the light was found to proceed from an abundance of small, semi-transparent, whitish, live worms which lay in it.
The commissioners appointed by parliament to inquire into the nature and extent of the bogs of Ireland, and the practicability of draining them, represent them as occupying thousands of acres, indeed, many square miles. Their nature and constituent parts are described by them as consisting of an accumulation of vegetable matter, settling in successive generations on itself, and converted by the want of ventilation and motion to a stagnant pool, which first furnished the elements of life and increase to the plants covering its surface. The progress of the accumulation may be best conceived by imagining a basin, or concave reservoir, of a certain extent and depth, formed of clay, limestone, gravel, &c., through which the water, scantily but constantly supplied, can not obtain an issue. Undisturbed in this water, a surface of bog moss grows, decays and putrefies. To this a second generation succeeds; and this is followed by others, until, at length, the bulk rises considerably above the level of its bed, forming hillocks of various hights, shapes and dimensions. The surface of a bog is not level like a lake, but undulating; and it terminates somewhat abruptly, and almost perpendicularly. The average hight of the great bogs, above the level of high-water mark in Dublin harbor, is about two hundred and fifty feet. Many acres of these bogs have been reclaimed; and the practicability of draining and cultivating the greater proportion of them has been pointed out in the reports of the commissioners.
Perthshire, in North Britain, abounds in mosses, the contents of which are computed to exceed nine thousand acres. The greatest hight of the moss, above the clay on which it lies, is fourteen feet and a half. Its surface, when viewed at a distance, seems wholly covered with heath: but when closely examined, is found to be composed of small tufts of heath, intermixed with a variety of moss-plants. Here also are found innumerable trunks of trees, lying along close to their roots, the latter being still fixed in the clay, as in the natural state.
The irruption of what is called Solway moss has greatly attracted the public attention; for, although the cause of it is obvious, still the alteration it produced on the surface of the earth, was more considerable than any known in Great Britain, as resulting from a natural cause, since the destruction of Earl Goodwin’s estate. It happened in the year 1771, after severe rains which had in many places produced great inundations of the rivers. The following is a concise description of the spot where this event happened. Along the side of the river Esk, is a vale, about a mile in breadth, bounded on the south-east by the river, and on the north-west by a steep bank, about thirty feet in hight above the level of the vale. From the top of the bank the ground rises on an easy ascent for about a quarter of a mile, where it is terminated by the moss, which extends about two miles north and south, and about a mile and a half east and west, being bounded on the north-west by the river Sark. It is probable that the solid ground, from the top of the bank above the vale, was continued in the same direction under the moss, before its irruption, for a considerable space; for the moss, at the place where the irruption happened, was inclined toward the sloping ground. From the edge of the moss there was a gully or hollow, called by the country people _the gap_, and said to be thirty yards deep where it entered the vale: down this hollow ran a small rill of water, which was often dry in summer, not having any other supply but what filtered from the moss.
The irruption happened, at the head of this gap, on the night of the sixteenth of November, between the hours of ten and eleven, when all the neighboring rivers and brooks were prodigiously swollen by the rains. A large body of the moss was forced, partly by the great fall of rain, and
## partly by the springs beneath, into a small beck or burn, which runs
within a few yards of its border to the south-east. By the united pressure of the water behind it, and of this beck, which was then very high, it was carried down a narrow glen between two banks about three hundred feet high, into a wide and spacious plain, over a part of which it spread with great rapidity. The moss continued for some time to send off considerable quantities of its substance, which, being borne along by the torrent, on the back of the first great body, kept it for many hours in perpetual motion, and drove it still further on. During the first night, at least four hundred acres of fine arable land were covered with moss from three to twelve or fifteen feet in depth. Several houses were destroyed, much corn lost, &c.; but all the inhabitants escaped. When the waters subsided, the moss also ceased to flow; but two pretty considerable streams continued to run from the heart of it, and carried away some pieces of mossy matter to the place where it burst. They then joined the beck, already mentioned, which with this addition, resumed its former channel, and with a little assistance from the people of the neighborhood, made its way to the Esk, through the midst of that body of moss which obstructed its course. Thus, in a great measure drained, the new moss fell several feet, and when the fair weather came on at the end of November, it settled in a firmer and more solid body on the lands it had overrun. By this inundation about eight hundred acres of arable ground were overflowed before the moss stopped, and the habitations of twenty-seven families destroyed.
Tradition has preserved the memory of a similar inundation in another part of North Britain. At Monteith a moss changed its course in one night, and covered a great extent of ground. There is also an account in the “Philosophical Transactions” of a moving moss near Churchtown, in Lancashire, which greatly alarmed the neighborhood, and was regarded as a miracle. The moss was observed to rise to a surprising hight, and soon after to sink as much beneath the level, moving slowly toward the south.
CORAL REEFS AND ISLANDS.
Coral belongs to the class of those surprising productions of nature, which are named _zoöphytes_, or plant-animals, on account of their filling up the intermediate space between the animal and vegetable kingdoms; and in treating of them this curious substance will be distinctly considered. In the mean time, the production of coral reefs and islands presents one of those geological changes, by which the earth’s surface has been modified, and has received a new accession from the sea.
The common foundation of the clusters of islands discovered by modern navigators in the Pacific ocean, as well as of those belonging to New South Wales, is evidently of coral structure, immense reefs of which shoot out in all directions. There is every reason to believe that the islands which are occasionally raised by the tremendous agency of subterraneous volcanoes, do not bear any proportion to those which are perpetually forming, by the silent but persevering efforts of the sea worms by which coral is produced. Banks of coral are found at all depths, and at all distances from the shore, entirely unconnected with the land, and detached from each other. By a quick progression, they grow up toward the surface; while the winds, heaping up the coral from deeper water, rapidly accelerate the formation of these banks into shoals and islands. They become gradually shallower; and when once the sea meets with resistance, the coral is quickly thrown up by the force of the waves breaking against the bank. These coral banks have been seen in all their stages: some in deep water; others with a few rocks appearing above the surface, just formed into islands without the least appearance of vegetation; and, lastly, others covered with soil and weeds.
The loose corals, rolled inward by the billows in large pieces, strike upon the grounds, and, the reflux being unable to carry them away, become a bar to the coagulated sand with which they are always intermixed. This sand, being easiest raised, is lodged at top; and when its accumulated mass is elevated by violent storms, and no longer within the reach of common waves, it becomes a resting-place to birds whom the search of prey draws thither. Their excrement, feathers, &c., augment the soil, and prepare it for the reception of accidental roots, branches and seeds cast up by the waves, or brought thither by birds. Thus islands are formed: the leaves and rotten branches, intermixing with the sand, produce in time a light black mold, in which trees and shrubs vegetate and thrive. Cocoa-nuts, which continue long in the sea without losing their vegetative powers, having been thrown on such islands, produce trees which are particularly adapted to all soils, whether sandy, rich or rocky. The violence of the waves, within the tropics, must generally be directed to two points, according to the monsoons. Hence the islands formed from coral banks must be long and narrow, and lie nearly in a meridional direction. Even supposing the banks to be round, as they seldom are when large, the sea meeting most resistance in the middle, must heave up the matter in greater quantities there, than toward the extremities; and, by the same rule, the ends will generally be open, or at least lowest. They will also commonly have soundings there, as the remains of the banks, not accumulated, will be under water. Where the coral banks are not exposed to the common monsoon, they will alter their direction, and become either round, or extended in the parallel, or of irregular forms, according to accidental circumstances.
Captain Flinders, in his voyage to the South Pacific, gives an account of an unbroken reef of coral, three hundred and fifty miles long, on the coast of New Holland; and he states, that between that country and New Guinea, the coral formations extend through a distance of seven hundred miles, interrupted by no intervals of more than thirty miles in length. He also gives us a lively and interesting description of a coral reef on the southern coast of New South Wales. On this reef he landed, and the water being very clear round the edges, a new creation, as it were, but imitative of the old, was presented to the view. Wheat sheaves, mushrooms, stags’ horns, cabbage leaves, and a variety of other forms, were glowing under water with vivid tints of every shade betwixt green, purple, brown and white; equaling in beauty, and excelling in grandeur, the most favorite _parterre_ of the curious florist. These were different species of coral and fungus, growing, as it were, out of the solid rock, and each had its peculiar form and shade of coloring; but, whilst contemplating the richness of the scene, the destruction with which it was pregnant could not be forgotten. Different corals in a dead state, concreted into a solid mass of a dull white color, composed the stone of the reef. The negro heads were lumps which stood higher than the rest; and being generally dry, were blackened by the weather; but even in these the forms of the different corals and some shells were distinguishable. The edges of the reef, but particularly on the outside where the sea broke, were the lightest parts; within these were pools and holes containing live corals, sponges, sea-eggs and cucumbers; and many enormous cockles were scattered upon different parts of the reef. At low water, these cockles seem most commonly to lie half open, but frequently close with much noise, and the water within the shells then spouts up in a stream, three or four feet high: it is from this noise and the spouting of the water that they are discovered, for, in other respects, they are scarcely to be distinguished from the coral rock.
His description of a coral island which he afterward visited on the same coast, is truly philosophical and throws great light on these surprising productions of nature.
“This little island, or rather the surrounding reef, which is three or four miles long, affords shelter from the south-east winds. It is scarcely more than a mile in circumference, but appears to be increasing both in elevation and extent. At no very distant period of time, it was one of those banks produced by the washing up of sand and broken coral, of which most reefs afford instances, and those of Torres’ strait a great many. These banks are in different stages of progress: some, like this, are become islands, but not yet habitable; some are above high-water mark, but destitute of vegetation; whilst others are overflowed with every returning tide. It seems to me, that, when the animalcules which form the corals at the bottom of the ocean, cease to live, their structures adhere to each other, by virtue either of the glutinous remains within, or of some property in salt water; and the interstices being gradually filled up with sand and broken pieces of coral washed by the sea, which also adhere, a mass of rock is at length formed. Future races of these animalcules erect their habitations upon the rising bank, and die in their turn, to increase, but principally to elevate, this monument of their wonderful labors. The care taken to work perpendicularly in the early stages, marks a surprising instinct in these diminutive creatures. Their wall of coral is for the most part in situations where the winds are constant, and when it reaches the surface, it affords a shelter, to the leeward of which their infant colonies may be safely sent forth; and to this their instinctive foresight it seems to be owing, that the windward side of a reef exposed to the open sea, is generally, if not always, the highest part, and rises almost perpendicular, sometimes from the depth of two hundred, and perhaps many more fathoms. To be constantly covered with water, seems necessary to the existence of the animalcules, for they do not work, except in holes upon the reef, beyond low-water mark; but the coral sand and other broken remnants thrown up by the sea adhere to the rock, and form a solid mass with it, as high as the common tides reach. That elevation surpassed, the future remnants, being rarely covered, lose their adhesive property; and remaining in a loose state, form what is usually called a _key_ upon the tops of the reef. The new bank is not long in being visited by sea-birds; salt plants take root upon it, and a soil begins to be formed; a cocoa-nut is thrown on shore; land birds visit it and deposit the seeds of shrubs and trees; every high tide, and still more every gale, adds something to the bank; the form of an island is gradually assumed, and last of all comes man to take possession. This island is well advanced in the above progressive state; having been many years, probably some ages, above the reach of the highest spring-tides, or the wash of the surf in the heaviest gales. I distinguished, however, in the rock which forms its basis, the sand, coral and shells formerly thrown up, in a more or less perfect state of cohesion; small pieces of wood, pumice-stone, and other extraneous bodies, which chance had mixed with the calcareous substances when the cohesion began, were inclosed in the rock, and, in some cases, were still separable from it without much force. The upper part of the island is a mixture of the same substances in a loose state, with a little vegetable soil, and is covered with the _casuarina_ and a variety of other trees and shrubs, which give food to paroquets, pigeons, and some other birds; to whose ancestors it is probable the island was originally indebted for this vegetation.”
-------------------------------------------
WIDE AND INHOSPITABLE DESERTS.
------------------------------------
ASIATIC DESERTS.
In Africa, as well as Asia, there are immense tracts of land called deserts, which consist of vast plains composed of loose sand. Large portions of these are utterly destitute of vegetation, and sometimes, in crossing them, the traveler sees not a hill or mountain, or human dwelling, or even a tree or shrub, or blade of grass. All around is a sea of sand; and far as the eye can reach, it is one scene of lifeless solitude and desolation. These trackless wastes are traversed by caravans, which are companies of travelers usually mounted upon camels. Horses travel in these sands with difficulty. Their feet sink in the soil; they are overcome with heat, and parched with drought. The camel, on the contrary, has a large, spongy foot, which does not sink in the sand; he can bear excessive heat, and by a curious contrivance of nature, is enabled to go without water for five or six days. This valuable creature is called the ship of the desert, because it enables the merchants of Asia and Africa to transport their merchandise over the sea of sand, just as a ship carries goods from one part of the world to another, across the briny ocean. It seems really as if Providence had provided this singular animal on purpose to enable mankind to traverse the great deserts which are spread out upon the eastern continent.
The chief Asiatic deserts are in Persia and Arabia, the former of which countries contains three of considerable extent and celebrity. The first of these commences on the east of the Tigris, in latitude thirty-three, and extends to the north of Shuster. The second reaches from the vicinity of Korn very nearly to the Zurra, in a line, from east to west, of about four hundred English miles, and from north to south, of about two hundred and fifty. In the latter direction it joins the great desert of Kerman, which, alone, extends over a tract of three hundred and fifty miles. The two may, therefore, be considered as forming one common desert, stretching north-west and south-east, over a space of about seven hundred miles; thus intersecting this wide empire into two nearly equal portions. This vast region is impregnated with niter and other salts, which taint the neighboring lakes and rivers, and has, on that account, been denominated the Great Saline Desert.
ARABIAN DESERTS.
The sandy deserts of Arabia form one of the most striking objects of that country. From the hills of Omon, which appear to be a continuation of those on the other side of the Persian gulf, as far as Mecca, the greater part of Negad is one prodigious desert, interrupted, toward the frontiers of Hejaz and Yemen, or Arabia Felix, by Kirge, containing the district of Sursa, and several _oases_, or fertile spots. The north-west part of Negad presents almost a continued desert, and is considered as a prolongation of the one above mentioned.
The Beled el Haram, or Holy Land of Islam, of which Mecca is the capital, is comprehended between the Red sea, and an irregular line which, commencing at Arabog, about sixty miles to the north of Djedda, forms a bend from the north-east to the south-east, in passing by Yelemlem, two days’ journey to the north-east of Mecca. It thence continues to Karna, nearly seventy miles to the east of the same place, and twenty-four miles to the west of Taif, which is without the limit of the Holy Land; after which, turning to the south-west, it passes by Drataerk, and terminates at Mehherma upon the coast, at the port named Almarsa Ibrahim, about ninety miles to the south-east of Djedda.
It therefore appears that the holy land is about one hundred and seventy miles in length, from the north-west to the south-east, and eighty-four miles in breadth, from the north-east to the south-west; which space is comprehended in that part of Arabia known by the name of El Hedjeaz, or the Land of Pilgrimage, and includes the cities of Medina and Taif. It has not any river; and the only water to be found, is that of some inconsiderable springs, which are not numerous, and the brackish water obtained from the deep wells. Thus it is a real desert. It is at Mecca and Medina alone, that cisterns have been wrought to preserve the rain-water; on which account, a garden is very rarely to be seen throughout this vast territory. The plains are composed either of sand, or barren earth, entirely abandoned; and, as the inhabitants do not, in any part of the country, sow any description of grain, they are supplied with flour, &c., from upper Egypt, Yemen and India.
AFRICAN DESERTS.
The most striking feature of Africa consists of the immense deserts which pervade its surface, and which are supposed to comprise the one-half of its whole extent. The chief of these is, by way of eminence, called Sahara, or the Desert. It stretches from the shores of the Atlantic, with few interruptions, to the confines of Egypt, a space of more than forty-five degrees, or about three thousand miles, by a breadth of twelve degrees, or about nine hundred miles; its whole extent being two-thirds as large as that of the United States. It is one prodigious expanse of red sand, and sandstone rock, of the granulations of which the red sand consists. It is, in truth, an empire of sand which seems to defy every exertion of human power or industry, although it is interspersed with various islands, and fertile and cultivated spots of different sizes, where water collects in springs or pools, around which vegetation springs up. These places, which present a delightful contrast to the surrounding sterility, and cheer the eye of the weary traveler, are called _oases_. Fezzan, or Fessan, is the chief of those which have been hitherto explored.