ART. II. A Description of the Western Islands of Scotland, including the Isle of Man; comprising an Account of their Geological Structure; with Remarks on their Agriculture, Scenery, and Antiquities. By John Macculloch, M.D. 2 Vols. 8vo. About 600 Pages in each, and 1 Vol. 4to. of Maps and Plates. 31. 38. Boards. Constable and Co. Edinburgh. Hurst and Co. London. 1819.

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E have repeatedly borne our testimony to the considerate and enlightened spirit which characterizes Dr. Macculloch's communications; and we are pleased to find that these volumes will amply sustain the reputation which he had already so justly earned, as a cautious, diligent, and independent observer, who is more solicitous to collect and establish facts than to defend preconceived theories. In various important respects, his Account of the Hebrides is intitled to a manifest preference when compared with those of preceding travellers. It embraces, in the first place, a much wider and a more diversified range of excursion, including every island deemed worthy of notice, from Rona to the Isle of Man; which last once formed a portion of the political system of the Western Isles. Secondly, more time and greater patience of research have been allotted to the survey, several of the islands having been visited more than once; and the maturation of the plan, which originated in a series of papers drawn up for the Geological Society, having occupied a period of four years. Thirdly, the geology and mineralogy of the respective islands are much more deliberately and accurately unfolded than in the partial and passing remarks of former tourists. I must not, however,' says the Doctor, terminate this part of the subject without noticing Professor Jameson's work on the same tract of country. I would willingly have shortened my own labour by being indebted to it, and am glad to bear testimony to the accuracy of his account, as far as the facts have been described. The difference of the plan on which this survey was conducted, rendered it necessary to examine every thing, and deprived me of the assistance which I might otherwise have derived from that work; which includes, moreover, but a small portion of the territory which has here been investigated.'

In the prosecution of his laborious undertaking, the author has evinced much zeal and intrepidity; encountering privations, fatigues, and perils, the very prospect of which would have appalled minds of a texture less robust and unyielding. The expense, too, necessarily incident to remote and desultory roaming by sea and land, would with many have operated as a discouragement; and we are not confident

that the charges of such a mission will be repaid with usury by the journal of its progress; or that for all his sacrifices the learned pilgrim will reap any other reward than the approbation of the discerning few, and the heartfelt consolation of having devoted his services to the cause of truth and science: since a fictitious narrative, which he might have penned at his ease in his closet, would probably have experienced a wider circulation than three volumes on the dull realities of rocky and weather-beaten islands. Aware, indeed, of the irksomeness inseparable from the undeviating description of objects which are connected by no other tie than that of juxtaposition, he has studied to avoid prolixity and unnecessary repetition, by reducing his more important observations to heads, or principles, and distributing the islands which he visited into five general divisions; while he contrives to relieve the attention by the occasional introduction of such miscellaneous topics as were naturally suggested in the course of his peregrinations. Yet the character of the publication is so decidedly geological as, with unscientific persons, to affect its popularity; and the style, though perspicuous, appropriate, and even occasionally eloquent, will be little relished by those readers who have formed their notions of excellence in this department on the models of our Gallic neighbours.

Of the five groupes of islands which form the subject of these volumes, the first four, namely, the Gneiss, the Trap, the Sandstone, and the Schistose, are so denominated from associations strictly natural; since the predominant geological features of each are the same, and they are not very materially disconnected by position: while the last division, relating to the Clyde islands, has been instituted chiefly on the principle of geographical situation; although the islands which compose it are also allied by certain common constitutional characters. By treating of them in this manner, the relations which they bear to the continent of Scotland will be the more readily understood; while from the great length of line [which] they occupy on the western coast, and the analogy of their structure and disposition to those of the continental strata, they will be found to illustrate in a very considerable degree its geological history.' The general north-easterly tendency of the western coast, and indeed of the main valleys and ridges of Scotland, is still exemplified, with a few exceptions, in the Western Isles; and the bearings of the coast and the ridges of the hills have been found, in most cases, to follow the direction of the strata.

To the Gneiss division belong Iona, Tirey, Coll, Barra, South and North Uist, Benbecula, Rona, Harris, Lewis, and several of inferior note.

The antiquities of Iona, so finely commemorated by Dr. Johnson, derive their importance from association, as monuments of comparative culture in an age of ignorance and barbarity; for Dr. M. assures us that, in any other situation, they would be consigned to neglect and oblivion. From his sagacious conjectures, we may likewise infer that the oldest of the ruined edifices on the island can scarcely date beyond the eleventh or twelfth century; and that the cathedral, from internal evidence, cannot be older than the early part of the thirteenth, and may be considerably more modern. In consequence of the progress of agriculture, and the rebuilding of cottages, the tomb-stones have been much deranged; and their antiquity appears to be very uncertain. One of the earliest, actually bearing a date, is that of LachJan Mackinnon, which is inscribed 1489. That of the Abbot Mackinnon, in the choir of the cathedral, was erected in 1500 but it is formed neither of black marble nor of basalt, as different writers have reported, but of mica-slate, containing a mixture of hornblend. The botanist must also be told that the byssus iolithus does not grow on this tomb, as mentioned by Lightfoot; but on that of the Abbot Kenneth, opposite, one of the Mackenzies of Seaforth.' Of the three hundred and sixty crosses (probably votive) which are said to have been in the island, three only remain: a few have been removed; and the greater number are reported to have been thrown into the sea by the orders of the reforming synod.

With regard to the population of this island, it amounts only to four hundred and fifty individuals, and the annual rent of the whole to 300l.; the tenantry depending for their scanty subsistence chiefly on fishing, the manufacture of kelp, and the rearing of cattle. Scattered patches of barley, potatoes, and a little rye, are cultivated on the light and level portions of the soil: but oats will not thrive, and are sown principally as pasture for the cattle. The principal rocks are, 1. A very black compact clay-slate, which occasionally contains hornblend, and in a few instances mica, and, a little below the village, is traversed by a vein of black basalt: 2. Compact felspar: 3. An insulated mass of white marble, occasionally tinged with green, mostly removed by working, incapable of receiving a good polish, in many places assuming a schistose tendency, mingling with the slate, and obeying its contortions: 4. Anomalous and ordinary gneiss, with a general vertical tendency, but presenting considerable irregularities; and, 5. Limestone, containing mica and noble serpentine. Of these, the gneiss is by far the most

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extensive. The rocks of green serpentine, mentioned by the late Dr. Walker as occurring on the shore at the south side of the island, and as capable of being quarried to any extent, seem to have no existence. The supposed specimens of jade are pebbles of green foliated steatite, and a pale yellowishgreen and dark-green noble serpentine, which have been detached from marble, and rounded on the beach; and the alleged compact epidote is a substance which occurs abundantly in all the rocks of the island, and may be referred to a variety of compact felspar.

Of Tirey and Coll, the geological structure is nearly identical. Over the low, flat, and unsheltered surface of the former, the wind blows with destructive violence: yet the soil, from the calcareous nature of the sand, and constant moisture, is not unfertile: though, towards the northern extremity, the rocks become numerous, and preclude the operations of the plough. As the island yields little turf for fuel, this necessary article is fetched, at considerable trouble and expense, from the opposite coast of Mull. With the exception of the salix argentea of Smith, not a single ligneous fibre can be traced. In many places, white clover, the faithful tenant of calcareous soil in the highlands of Scotland, prevails over the grasses. The cultivated crops, if so they may be termed, consist of potatoes, barley, oats, and flax; which not unfrequently prosper, even under wretched management. Dr. M. takes a retrospect of the general style of farming in these islands, where many of the old and injudicious practices still prevail : but others are gradually giving way to more enlightened and considerate views, especially since the introduction of the potatoe, which is now supposed to form two-thirds of the subsistence of the natives.

The great gneiss chain of Tirey and Coll is generally characterized by the presence of hornblend, though mica is also observed, especially in the vicinity of those granite veins by which it is so abundantly traversed. Sometimes it is perfectly foliated, but at others is not easily distinguishable from granite; and, when the quartz disappears, it assumes an aspect intermediate between gneiss and granite, and may be observed to pass into hornblend-slate, or into primitive greenstone, or, in some cases, into a mere unfoliated hornblendrock. Wherever it is visible, it is usually more or less bent and contorted. The flesh-coloured marble of Tirey is an irregular mass, of about one hundred feet in diameter, enveloped in the gneiss. It occasionally contains large concretions of black and shining hornblend, two inches or more in length: but it is mostly distinguished by the quantity of dark

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green augite dispersed through it, which contrasts with the reddish tone of the ground. The quarries have been badly wrought, and nearly ruined by the injudicious use of gunpowder. Another and much larger mass of primitive limestone, or marble, also involved in the gneiss, is characterized by a white ground, an occasional admixture of serpentine or steatite, and particularly by sahlite, in the form of small grains dispersed in the mass. The notices with which we are here presented of this mineral, as it occurs in a few repositories in Scotland, will prove highly acceptable to the curious reader. Sphene has been also remarked in the pinkcoloured marble, but it occurs very sparingly, and in_minute crystals.

The surface of Coll is more rocky than that of Tirey, and, towards its southern and western shores, considerable tracts have been overwhelmed by accumulations of drift-sand, notwithstanding which the arable and pasturing spots are calculated at one third of the whole extent. Eriocaulon decangulare, hitherto found only in Sky, has been discovered in some of the lakelets of this small island. The direction of the gneiss beds, where it can be traced, is north-easterly, and their dip is towards the east; their elevation varying from 15 to 80 degrees. In several places, distinct beds of mica-slate are found regularly alternating with it. A still more remarkable appearance is that of a bed similarly situated, and consisting of a conglomerated rock formed of fragments of quartz imbedded in a micaceous schist; offering an example of a breccia in a situation where these have not been supposed to exist. This rock is to be seen in a small bay near Ben Feoul.' In In every instance in which examination is practicable, the gneiss beds appear to have been shifted by the passage of the granite veins.

However obscure the name of Barra may be to many of our readers, the island which it designates extends to ten miles in length and seven in breadth, and is a station for the fishing of ling, which is cured, and exported to Greenock, Glasgow, &c. This traffic, which is prosecuted under considerable inconvenience and discouragement, extorts from the benevolent tourist some excellent reflections on the economical management of highland property. Like many of the adjoining islands, Barra is very deficient in permanent streams and springs of water; and the surface is chiefly peat, incumbent on the bare rock, or sand blown up from the shore. Here the refractory nature of the gneiss affords neither alluvial depositions nor accumulated fragments at the foot of precipices: yet so irregular is its disposition, that

the