tre, and that disposition being arranged every where according to the shape of the cavity, sufficiently refutes the idea of the matter of agates being deposited in the hollow by infiltration, besides, that infiltration would happen in one direction only, there is no source from which the matter of agate can appear to have come, and if we suppose a regular permeability of the rock to such matter, we should expect to find its pores choaked up with this matter, and that it regularly proceeded downward to form a solid stratum of its own substance. We may again ask, on the supposition of a matter pervading the rock, how it comes to pass, that the different cavities, yet very near to each other, shall be filled with very different substances, one with calcareous spar, a second with the matter of flint, a third with mineral pitch, and perhaps all three combined in one cavity, yet preserving their substances distinct; and we very well know, that if either of these substances had already occupied the pores of the rock, that neither of the others could pass. Besides this, we know of no cause that can render two of the aforementioned substances, viz. the silicious and bituminous, capable of penetrating any porous body, to do which they must be fluid. We are, therefore, to suppose one of two things, either that these substances have assumed their present form, in the place where they are now found, and that they have either originated from a change or separation of some mixed mass, in which they were once combined, or that they have been collected together, from having once been dispersed each in its proper substance, through the main mass of the rock..

It appears also, that these matters have arranged themselves according to their different degrees of fusibility, as far as we know their chemical properties. To pursue the same instance, we next note, that of the three substances mentioned, one only is soluble in water, viz. the calcareous spar, and that this appears to have been neither the first nor the last of these three, in passing from a fluid to a solid form, but also that we know of no power capable of liquifying either of the other two substances, except fire, and that were fire the supposed agent, the order of their arrangement would

justify the conjecture, the least fusible, viz. the flint, having cooled the first, then the calcareous spar, and lastly, the mineral pitch in the centre. Not that it is at all impossible that water too may have had its share in forming the calcareous spar, though that water may have afterwards escaped from the cavity; and the circumstances under which the mineral pitch is found, not closely adhering to either of the other substances, but preserving itself in the centre distinct from them, seems to favour this idea, because, unless the bitumen had been disunited from them by the intervention of a medium, with which it is not miscible, there seems to be no reason why it should not, on cooling, have subsided into the crevices of the silicious mineral. We know that water can make its escape from such cavities, and it has been also found in cavities lined with different coats of silicious matter, in the manner of these agates.

It does not follow, however, that water in all cases shall have occupied these hollows which are now found, nor that it shall have occupied, in any instance, the whole of that hollow space, because any elastic fluid either separated from the substance by heat during either their disunion or mere fusion, will alone be sufficient to make for itself, however compressed, some hollow space or bubble, such as the appearance of air bubbles in glass, which are there called blebs.

It would be endless to speak of the variety of substances which are thus found having the same structure as agate. Of the silicious stones of which I am now speaking, it may be sufficient to observe, that they have every where throughout the same rock an external coating similar in them all. In some this is a thin layer of steatite, frequently green. In others, it consists of a very hard transparent coating of agate. If this coating were the only one lining the hollow, it would be found to present an internal surface, protruding inwards in numerous small eminences, and producing that surface which we call mammilated, which proceeds entirely from the fluid parts having arranged themselves round the little roughnesses of the hollow. Let us suppose upon one plain surface a single projecting point, and that on this surface the fluid matter was to

arrange itself coat by coat, we should then have a particular projection of the coats over the prominent point, in semicircular curves; and let us then take a case less simple, and suppose that plane surface bent round into a circle, and that one or more of these prominent points presented themselves, we should then have a number of semicircular congeries corresponding to the number of the points; and if the induration were to proceed slowly, these points would still prevail till the whole of the matter was indurated, and these semicircular curves would at length meet each other in the middle, as circles on the water interfere with each other. But when the points from which these semicircles proceed are not very prominent, they soon lose their effect, by being covered with a succession of coats, the irregularities become less and less unequal, till at length they have only the effect of a plane surface little varied, and from that surface the coats proceed regularly inwards. These semicircular appearances are called eyes, and from their being lodged immediately within the hard transparent coating, that may afterwards be cut away, so as to present a large surface of these eyes, are much prized by collectors. The more colourless of these stones are called calcedonies, and the other agates, though the term agate is used indiscriminately for both; and indeed whenever silicious substance appears to have been indurated, layer after layer, upon any other substance, that mode of deposition which is in fact only a stalactite, has in the silicious stone been termed from this substance agatization.

Thus we have jasper agates in which colour abounds, and agatized jaspers in which the stalactite abounds. There are two appearances, however, in some of these pebbles, which are less easy of explanation than those already mentioned; one has the appearance of icicles as it were, or stalactites of the matter of agate or calcedony found hanging down in these hollows, and the coats regularly formed round them, as the coats of wax or tallow are round the wick in the process of candle-making. In the centre of these, and in their longitudinal direction, we generally find a black line, and frequently some more projecting part of the substance of the

matrix. These are sometimes found in cavities, and we have sometimes something like a demonstration of their having existed even where the cavity is entirely filled up, and often appear to have been indurated prior to the rest of the substance, i. e. we find the rest of the substance everywhere circumfused, filling up their interstices, and this seems to be the only plausi ble argument which favours the idea of infiltration; but we need look no farther for its refutation than the very circumstance now alluded to, i. e. the acknowledged existence of one or more coats of silicious substance already formed within the hollow, which coats, though not dense enough to prevent the escape of water, and in the same manner its ingress, are certainly too compact to suffer fluid flint or calcedony to pass through them.

If, therefore, we observe, now and then, some instances of a predisposi tion in particular parts of a mass to arrange themselves before the rest, and in a form differing from the obvious and general one, we shall be the less surprised at finding a second deviation, which is next to be mentioned, i. e. a stratified or onyx form. These are sometimes found constituting the whole substance of the agate, running in straight and parallel lines from one side of the mass to the other; and it is this appearance that has given rise to the conjecture of these being only fragments of regular crystallized bodies, which have been enveloped by the mass which now contains them, whilst it was in a fluid form. But proof is not wanting that the stalactitical form already mentioned is sometimes produced in these very hollows where we have seen that fire can have been the only cause of fluidity; and also that where these stalactites prevail, this onyx form of arrangement makes a part of the same agate; and indeed we most frequently find, that these straight lines, instead of cutting the pebble from side to side, are continued in the other parts of the pebble in a curved form. When they appear wholly consisting of straight lines, it may perhaps be accounted for, from the whole mass taking a disposition to congeal, at the same time, that one mode of formation prevails throughout, as we see in some jaspers where sometimes stars prevail, and sometimes arbo

a farther use of amygdaloid rock, by finding occasionally buried in its substance certain regular hard bodies which abound also in many other rocks; and, from putting circumstances together, we shall be enabled to infer, that the same formal cause has given rise to all of them. Thus, from a single specimen, well understood, and taken with its consequences, a whole theory would flow, or might be collected. It appears, that, in the coloured agates, in consequence of the change from a fluid to a solid state, those colours have been separated into distinct layers, which we are to suppose were before diffused through the whole mass, and that, in consequence of that change, whether produced by the subduction of fire, (i. e. the gradual cooling of the matrix,) or any other cause of induration, the colouring matter has been separated, layer after layer, sometimes to a very minute division; and we frequently find different layers of the same colour disposed at unequal distances from the outward surface, so that it appears that the central matter, which was the last indurated, seems to have been of the same nature with the external or first indurated. Sometimes we find these hollows filled almost wholly with the pure matter of quartz, which, if there is any void space, crystallizes; and it seems as if, after all the colouring matter of an agate has been deposited in successive layers, that the matter of quartz remains colourless, and crystallizes in the centre. The colouring particles, if examined with a microscope, and also sometimes to the naked eye, appear in the form of little spheres, according to the laws of fluids before mentioned.

rization. It might be supposed also, in some measure, owing to the gradual process of deposition, were we to suppose the main mass or matrix to be at rest. But, if we suppose fire to have been the cause of the fluidity of these pebble rocks, motion is generally a concomitant circumstance of fluidity; and we are therefore at liberty to suppose, not merely the motion of the main mass concerned, which was checked only by its congealing, but also no small share of intestine motion, from the fresh union and disunion, were it only the mechanical mixture of such heterogeneous substances as abound in these rocks. A regular process of deposition may, therefore, have been interrupted when half finished, and the matter afterwards compelled to arrange itself according to the more confined form of the hollow, producing the appearances which more generally take place. There appears also in these regularly stratified pebbles another mark of slow induration, i. e. the stellar or spherical formation of some of its parts. Whether any principle of repulsion may have had its share in their formation, it does not seem probable that we shall ever be able to determine. It may be observed, that, according as the mass is of coarser or finer materials, so is the regularity or sphericity of these, whether pebbles or mere hollows. An accurate knowledge of these rocks, and of the structure of an agate, will do more towards explaining the great phenomena of Nature than any other principle we can adopt. The forma tion of an agate, depending upon the simple laws of attraction between similar particles, when left at liberty to follow that attraction, may be extended to masses of matter of any magnitude; and, were we to suppose the whole globe of our earth perfectly fluid, either from fiery fusion or mechanical suspension of its parts in water, it is obvious that an arrangement would take place of its particles, similar in form, and opposite in the manner, the centripetal force, causing different strata to be arranged round a centre or nucleus. Thus it is that spheres are formed every day upon a smaller scale; and magnitude is not concerned with either chemical or physical operations. We shall make

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Those cavities which contain a variety of substances exhibit, therefore, when any void space is left, some of the most perfect crystals in their hollows; and the same may be observed of the most hollow or freest parts of veins, whether filled by earths or metallic matter. It will admit of a question, whether these substances in cooling may not contract, and thus tend to produce these central cavities. A probable cause of the separation of the colouring matter is the cooling of that fluid, which before held them in solution.

3 M

The Border Antiquities of England and Scotland; comprising Specimens of Architecture and Sculpture, and other Vestiges of Former Ages, accompanied by Descriptions. Together with Illustrations of remarkable incidents in Border History and Tradition, and Original Poetry. By WALTER SCOTT, Esq. 2 vols. quarto, 1814 and 1817. London, Longman and Co.

Or the different regions into which our country is divided, it may be said, that, as the Highlands possess the greatest attraction for the lover of nature in her sublimest and most interesting forms, so the Border has charms to fascinate all those who delight in romantic enterprise, and poetic fancy. This boundary between two warlike and long hostile kingdoms, became naturally the great theatre on which the achievements of the feudal ages were performed. The habitual hostility, too, with which the inhabitants of the opposite side of the March viewed each other, gave rise to a constant series of minor exploits, which, though they could not find a place in history, kept alive the habits of activity, enterprise, and daring vafour, and held men's minds in a state of perpetual excitement. The same causes which rendered this spot the theatre of war, rendered it also a land of song; for true and native poetry is the result, not of monastic and studious seclusion, but of those eventful circumstances which fire the imagination, and melt the heart. It is evident that the flame, which animates the genius of our great Scottish minstrel, has been kindled at the recollection of the deeds of his forefathers. Had not the splendour of his own effusions so far eclipsed those of the nameless bards whose works he has with kindred sympathy collected, these last, perhaps, might have held a higher place in our estimation; and, even as they stand, when due allowances are made, they certainly appear entitled to hold no mean rank among the poetic monuments of the feudal ages. The adventures which they relate are not con

fined to the mere exploits of marauding warfare; gallantry and attachment to the fair sex had found a place in these rude breasts; and in such unsettled and boisterous times, the alarms, perils, and disasters, to which the fair objects of their admiration were perpetually exposed, afforded incidents which it required only a moderate share of invention to weave into an interesting and poetic narrative.

Another effect of this constant state of warfare upon the Borders, was the construction of "towers of defence," which, if they could not aspire to the rank of fortresses, might at least afford protection against sudden inroad; and, if they could not repel an invader, might retard his progress. These could not, indeed, rival the pomp and magnificence of those mansions which, in the interior of Scotland, and the less troubled districts of England, were erected by the great nobles for the display of baronial splendour. A square tower built on a height, with walls of immense thickness, and a few narrow loop-holes for the admission of light, and the discharge of missile weapons, formed usually the whole array of a Border castle. Some, however, belonging to the great nobility, were built on a scale of greater magnificence; they are placed generally in a

picturesque situation, and all of them recal events in history and tradition which must be interesting to a large portion of the present generation. It is well, therefore, in this age of graphic ornament, when it seems destined that every thing on which the eye can look, must be embodied by the graver, and collected into handsome volumes for the amusement of the amateur, that these monuments of the prowess of our forefathers should not escape delineation. Besides the military, ecclesiastical monuments of considerable interest here present themselves. These wild spirits, amid their devotion to fight and plunder, did not remain insensible to the influence of a faith so calculated to dazzle the senses as that of Rome. The sword and the breviary went hand in hand, and the spoils of Eng

land were partly employed in the erection of religious houses, for the celebration, with due pomp, of the Catholic rites.

The present work, certainly, does credit to those by whom it was projected and executed. The different plates appear to be well designed and engraved, and the points of view in general happily chosen. We were particularly pleased with the castles of Newcastle, Carlisle, Warkworth, Bamborough, Naworth; the monasteries of Lanercost, Tynemouth, Jedburgh, Lindisfarne. Melrose is familiar to us on a more satisfactory scale than the present work admits. Several of the interiors appear to us very interesting, and deeply impressed with that pleasing sentiment which carries us back into the inmost recollection of past ages.

We think the work, however, would have been improved, if some kind of arrangement had been followed. At first, indeed, an attempt seems to be made at this; but it is soon abandoned, and the objects are heaped together in utter confusion. We are aware, that, in a periodical work, some regard might be necessary to the varying degree of dispatch afforded by the different artists. But, with a little good management, it might surely have been so arranged, that, at the conclusion of the whole, the chaos might have been unravelled, and some system of order established.

To this work is prefixed an introduction of considerable length, and of very peculiar value and interest. We need only mention, that it comes from the pen of Mr Scott, and that it contains illustrations of remarkable incidents in Border history and tradition, to satisfy the reader, that they will be described at once with historical accuracy, and with that poetic feeling which gives them their chief interest. Mr Scott begins by remarking the striking aspect presented by a country which, after having long been the theatre of national hostility, has remained for some time in a state of

peace. "Numerous castles left to moulder in massive ruins; fields where the memory of ancient battles still lives among the descendants of those by whom they were fought or witnessed; the very line of demarcation which, separating the two coun

tries, though no longer hostile, induces the inhabitants of each to cherish their separate traditions,-unite to render these regions interesting to the topographical historian or antiquary. He then describes the antiquities of the Britons, of which the most remarkable are the extensive entrenchments known by the name of the Catrail, and the remains of an irregular hill fort, situated on the grounds of Mr Pringle of Fairnilee. This is followed by a view of the Roman antiquities, which, besides their great roads, and the remains of the wall of Antoninus, consist chiefly of arms and sepulchral monuments. At length the time came when the Saxons, partly as conquerors, and partly as refugees, filled the whole low country of Scotland, and finally communicated their language to that part of the kingdom. Our author, however, observes, that the system of clanship which was originally Celtic, and unknown to the Saxons, was borrowed by the latter, and adopted on the Borders to nearly as great an extent as in the Highlands. Of this remarkable form of political association, a very striking picture is given. The most flourishing period of Border history was the reign of David I. when the splendid monasteries of Kelso, Jedburgh, Melrose, and Dryburgh, were founded. The castles also of Roxburgh and Jedburgh, then standing, appear to have surpassed any military stations erected in later times. After the usurpation of Edward I. and the succession of desolating invasions with which Scotland was afflicted, the Scots ceased attempting to defend regularly their frontiers. The consequences are thus described:

"It followed, from this devastating system of defensive war, that the Scottish were so far from desiring to cover their borders by building strong places or fortresses, that they pulled them down and destroyed them where they already existed. Buchanan has elegantly turned this systematic destruction of their castles into a compli ment to the valour of his countrymen ;

Nec fossis et muris patriam sed Marte tueri.

But, without disparaging Scottish valour, the motive of leaving their frontier thus open, seems to have been a consciousness that they were greatly surpassed by the English both in the attack and defence of their strongholds ;-that if they threw their best warriors into frontier garrisons, the