Obrázky na stránke
PDF
ePub

the level of the sea, and have commonly an inequality of surface, which renders them distinct in appearance from the morasses of England. Although in many instances they extend over a vast expanse of level country, they often stretch over the sides or tops of mountainous elevations. The spontaneous growth on the surface is usually heath, blended with bog-myrtle, rushes, and sedgy grass; all being of little or no use to man.

The bogs of Ireland have been concisely described by Mr. Davy, in a letter inserted in Wakefield's Account of Ireland, as consisting of inert vegetable matter, covered more or less with unproductive vegetables, and containing a large quantity of stagnant water.” Respecting their origin, various ingenious conjectures have been made, but no satisfactory mode of accounting for their formation has yet been submitted to the public. It is generally believed that they are not primitive, or original, masses. Under some bogs, of a considerable depth, there have been discovered the furrows of land, once ploughed ; and various sorts of trees, the most common being the oak, the fir, and the yew, are found in great abundance. Some of these trees appear to have been broken, as if by tempest, or through the operation of time; others retain the mark of the axe ; but more evince the agency of fire, and were, perhaps, levelled through that medium during the warfare of the early inhabitants, when the abundant woods formed places of retreat and defence.

In consequence of the frequent discovery of trees at various depths in the bogs, it has been supposed that dilapidated forests caused the formation of these vast turbaries. Trees," writes Mr. Young, “ lying very thick on the ground, would become an impediment to all streams and currents, and gathering in their branches whatever rubbish such waters brought with them, would form a mass of substance which time might putrify, and give that acid quality to, which would preserve some of the trunks, though not the branches, of the trees.” The spots on which traces of the plough are found, the same author conjectures to have formerly been fields, adjoining the woods, which were overwhelmed by the bog when it rose superior to its first boundaries.

This mode of accounting for the origin of bogs is liable to many objections. The following argument, in opposition to the popular opinion, is of considerable weight, and is adduced on the authority of Mr. Griffith, one of the most observant and intelligent of the gentlemen employed in the survey of the bogs, by direction of the Irish commissioners. In the first report of those commissioners it is remarked by Mr. Griffith that such bogs as came under his notice were, assuredly, not produced by any cause resembling that mentioned above, “ as trees, , or the branches of trees, are rarely found in the interior of the deep and extensive bogs of Ireland, but are always met with at the edges, or near gravelly hills or islands in these bogs, lying horizontally, and in no particular direction ; frequently crossing each other, and either attached to their roots or separated from them. In the latter case the stumps usually stand upright in the place where they grew, having six or eight feet of the bog sometimes above them, and three, four, and five feet, but rarely more, below their roots."

Whilst we dissent from the opinion of those who ascribe the formation of bogs to the agency of decayed timber alone, we think it indisputable that the obstruction produced by fallen woods proved greatly assistant in the operations of nature. On this subject an augmentation of inconclusive argument can be scarcely desirable ; and we proceed to the notice of some particulars which are independent of theory and speculation.

The aquatic vegetables of which the Irish bog is composed are produced annually, and in proportion to the quantity of water contained on its surface. It is very easy,” observes a recent writer, of much experience and judgment on this subject, (Mr. Thompson, in his Survey of Meath) “ to discern each year's growth, at least for the last twenty years, by examining a section of the bog, and considering, that it increases every year in as great a degree as it bears moss on its surface. The moss grows every summer, and is killed the following winter by the frosts; each year's growth forms a stratum, through which the next summer's heat draws a fresh crop, which dies in like

manner. Every year's growth may, therefore, be easily distinguished, lying horizontally in strata. Bogs are considerably higher in winter than they are in summer, perhaps three feet on a deep wet bog. This is very manifest to any person who takes the trouble of standing on one side, and marking an object just visible over the surface at the other side of the bog : this object, though visible in the months of August or September, will not be so in February or March following. The cause is obvioùs ; the heat of the summer's sun, and the dryness of the atmosphere, cause exhalations from the bog, which deprive it of a considerable part of the

part of the water with which it was surcharged in the winter, thereby contracting and consolidating its surface, which being of a spongy nature, is swelled again by the rains of the succeeding winter, so that bogs are in a perpetual state of contraction and dilatation."

Our preceding division of the bogs of Ireland into two sorts, the black and the red, may, perhaps, admit of amplification, since the kind usually termed the floating bog does not fall strictly under either of those descriptions. By this term is understood an extensive mass, consisting, like that already noticed, of decayed aquatic vegetables, but having a large collection of water at the bottom. Instances have occurred in which bogs of this kind, when greatly surcharged with under-water, have burst their surface, and poured, in a black and destructive deluge, over the contiguous country. Such phenomena are noticed in our description of the King's County, and the counties of Tipperary and Galway. It will be recollected that circumstances so fearful are not peculiar to Ireland. Solway Moss, in Cumberland, and Chat Moss, in Lancashire, have experienced similar eruptions, an account of which is presented in the “ Beauties of England.”

That the bogs possess a strong antiseptic quality has been sufficiently ascertained, by the discovery of numerous animal and vegetable substances, free from important marks of decay, at a considerable depth beneath the surface. It may be readily supposed that such wide extents of aquatic vegetation impart a local increase of coldness to the climate ; but it is certain that

they do not communicate any injurious qualities to the atmosphere, as is usual with the morasses of other countries. Dr. Campbell has observed, in his “ Philosophical Survey,” that “ the watery exhalations from the Irish bogs are neither 80 abundant, nor so noxious, as those from marshes, which become prejudical from the various animal and vegetable substances, which are left to putrify as soon as the waters are exhaled by the sun." The numerous persons who dwell in the vicinity of the boigs are not subject to any peculiar diseases, denoting a natural source of unhealthfulness.

The timber found in the bogs of Ireland is often of a large size, though considerably diminished from its original proportions, as the outward parts have sunk to decay and been decomposed. Thus the heart of the tree only remains', and this, in the instances of the fir, the oak, and the yew, is applicable to various useful purposes, having acquired a degree of hardness superior to that of wood prepared in the usual manner. Its texture is, indeed, so firm, that the operations of the saw are performed with much difficulty; and its durability often proves great, under all the trying vicissitudes of the atmospheric air. The kinds of timber found in the bogs are confined to oak; fir; yew ; holly; and birch. Mr. Wakefield states, as the result of his investigations on this subject, that the black bogs abound with oak timber, and the red with fir, whilst yew and holly are found in bogs of every description.*

Bog-turf is used as a manure, both when reduced to ashes and in its original substance; but chiefly in regard to a species which is useless as fuel.

* Account of Ireland, vol. i. p. 525.-In Dutton's Survey of Clare is the following remark concerning the method used by the peasantry of Ireland in discovering timber secreted in the bogs :—" Very early in the morning, before the dew has evaporated, a man with a long sharp spear goes out into the boġ, and as the dew never lies on the part over the trees, be they ever so deep, he can ascertain their length, and by thrusting down his spear he easily discovers whether they are sound, or rotten ; if sound, he marks with a spade the spot where they lie, and at his leisure proceeds to extricate them from their bed.”

[ocr errors]

There appears no cause for doubting but that, in past ages of gloom and national warfare, the less civilized of the inhabitants were desirous of encouraging, rather than of restraining, the increase of dreary and deceptive moss-lands, which acted as places of retreat to their own accustomed footsteps, while they presented barriers impassable, or dangerous, to foreign assailants. In recent more tranquil and enlightened times, there has naturally been entertained a very general desire of placing so extensive and unprofitable a portion of the island under judicious cultivation. The bogs of Ireland, when reclaimed, form meadow and pasture of great excellence. Commissioners have been appointed by government to examine into their extent, natural character, and capacity of improvement. The reports of these gentlemen are published, and contain much curious and useful information,

RIVERS AND LAKES.— Ireland is watered by many large and beautiful rivers, highly favourable to commercial interchange ; and by very numerous rivulets, which intersect the country in nearly every direction. It is believed that there are in this island, exclusive of contributory and small streams, one hundred and twenty-five rivers which flow directly into the sea, or its different inlets; and it must be noticed, as a felicitous circumstance, that those rivers which are navigable for the greatest extent, pass through the finest and most productive parts of the country. In most instances they, also, fall into capacious and excellent harbours.

The Shannon is the principal river of freland. This noble river is usually said to have its rise at Lough Clean, in the county of Leitrim ; though the honour of producing it is also claimed by a spot near Florence Court, in the county of Fermanagh. In its progress towards the south-west it nearly insulates the province of Connaught and the county of Clare. Its course, according to the statement of Mr. Newenham, from abreast of Kerry Head, to Ballintrane Bridge, at the entrance of Lough Allen, through which it passes from Lough Clean, is 170 English miles in length." In this extensive flow it waters, the borders of the following counties : Leitrim ; Roscommon; Long

« PredošláPokračovať »