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tre, and that disposition being ar- justify the conjecture, the least fusiranged every where according to the ble, viz. the flint, having cooled the shape of the cavity, sufficiently refutes first, then the calcareous spar, and the idea of the matter of' agates being lastly, the mineral pitch in the centre. deposited in the hollow by infiltra- Not that it is at all impossible that tion, besides, that infiltration would water too may have had its share in happen in one direction only, there is forming the calcareous spar, though no source from which the matter of that water may have afterwards escapagate can appear to have come, and ed from the cavity; and the circumif we suppose a regular permeability stances under which the mineral pitch of the rock to such matter, we should is found, not closely adhering to either expect to find its pores choaked up of the other substances, but preservwith this matter, and that it regularly ing itself in the centre distinct froin proceeded downward to form a solid them, seems to favour this idea, bestratum of its own substance. We may cause, unless the bitumen had been again ask, on the supposition of a disunited from them by the intervenmatter pervading the rock, how it tion of a medium, with which it is comes to pass, that the different cavi- not miscible, there seems to be no reaties, yet very near to each other, shall son why it should not, on cooling, be filled with very different substan- have subsided into the crevices of the ces, one with calcareous spar, a second silicious mineral. We know that wawith the matter of flint, à third with ter can make its escape from such camineral pitch, and perhaps all three vities, and it has been also found in combined in one cavity, yet preserv- cavities lined with different coats of ing their substances distinct; and we silicious matter, in the manner of very well know, that if either of these these agates. substances had already occupied the It does not follow, however, that pores of the rock, that neither of the water in all cases shall have occupied others could pass. Besides this, we these hollows which are now found, know of no cause that can render two nor that it shall have occupied, in any of the aforementioned substances, instance, the whole of that hollow viz. the silicious and bituminous, ca space, because any elastic fluid either pable of penetrating any porous body, separated from the substance by heat to do which they must be fluid. We during either their disunion or mere are, therefore, to suppose one of two fusion, will alone be sufficient to make things, either that these substances for itself, however compressed, some have assumed their present form, in hollow space or bubble, such as the the place where they are now found, appearance of air bubbles in glass, and that they have either originated which are there called blebs. from a change or separation of some It would be endless to speak of the mixed mass, in which they were once variety of substances which are thus combined, or that they have been col- found having the same structure as alected together, from having once gate. Of the silicious stones of which I been dispersed each in its proper sub- am now speaking, it may be sufficient stance, through the main mass of the to observe, that they have every where rock.

throughout the same rock an external It appears also, that these matters coating similar in them all. In some have arranged themselves according this is a thin layer of steatite, freto their different degrees of fusibility, quently green. In others, it consists as far as we know their chemical pro- of a very hard transparent coating perties. To pursue the same instance, of agate. 'If this coating were the only We next note, that of the three sub- one lining the hollow, it would be stances mentioned, one only is solu- found to present an internal surface, ble in water, viz. the calcareous spar, protruding inwards in numerous small and that this appears to have been eminences, and producing that surface neither the first nor the last of these which we call mammilated, which three, in passing from a fluid to a so- proceeds entirely from the fluid parts lid form, but also that we know of no having arranged themselves round the power capable of liquifying either of little roughnesses of the hollow. Let the other two substances, except fire, us suppose upon one plain surface a and that were fire the supposed agent, single projecting point, and that on the order of their arrangement would this surface the fluid matter was to

or

arrange itself coat by coat, we should matrix. These are sometimes found in then have a particular projection of cavities, and we have sometimes somethe coats over the prominent point, thing like a demonstration of their in semicircular curves; and let us then having existed even where the cavity is take a case less simple, and suppose that entirely filled up, and often appear plane surface bent round into a circle, to have been indurated prior to the and that one or more of these promi- rest of the substance, i. e. we find the nent points presented themselves, we rest of the substance everywhere cirshould then have a number of semi- cumfused, filling up their interstices, circular congeries corresponding to the and this seems to be the only plausinumber of the points; and if the indu- ble argument which favours the idea ration were to proceed slowly, these of infiltration ; but we need look no points would still prevail till the whole farther for its refutation than the very of the matter was indurated, and these circumstance now alluded to, i. e. the semicircular curves would at length acknowledged existence of one meet each other in the middle, as more coats of silicious substance alcircles on the water interfere with ready formed within the hollow, each other. But when the points from which coats, though not dense enough which these semicircles proceed are to prevent the escape of water, and in not very prominent, they soon lose the same manner its ingress, are certheir effect, by being covered with a tainly too compact to suffer fluid flint succession of coats, the irregularities or calcedony to pass through them. become less and less unequal, till at If, therefore, we observe, now and length they have only the effect of a then, some instances of a predisposiplane surface little varied, and from tion in particular parts of a inass to that surface the coats proceed regu- arrange themselves before the rest, larly inwards. These semicircular ap- and in a form differing from the obpearances are called eyes, and from vious and general one, we shall be the their being lodged immediately with- less surprised at finding a second dein the hard transparent coating, that viation, which is next to be menmay afterwards be cut away, so as tioned, i. e. a stratified or onyx form. to present a large surface of these These are sometimes found constituteyes, are much prized by collectors. ing the whole substance of the agate, The more colourless of these stones running in straight and parallel lines are called calcedonies, and the other from one side of the mass to the other ; agates, though the term agate is used and it is this appearance that has indiscriminately for both; and indeed given rise to the conjecture of these whenever silicious substance appears being only fragments of regular crysto have been indurated, layer after tallized bodies, which have been envclayer, upon any other substance, that loped by the mass which now conmode of deposition which is in fact tains them, whilst it was in a fluid only a stalactite, has in the silicious form. But proof is not wanting that stone been termed from this sub- the stalactitical form already mentionstance agatization.

ed is sometimes produced in these Thus we have jasper agates in which very hollows where we have seen that colour abounds, and agatized jaspers fire can have been the only cause of in which the stalactite abounds. There Auidity; and also that where these are two appearances, however, in some stalactites prevail, this onyx form of of these pebbles, which are less easy arrangement makes a part of the same of explanation than those already agate; and indeed we most frequentmentioned ; one has the appearance ofly find, that these straight lines, inicicles as it were, or stalactites of the stead of cutting the pebble from side matter of agate or calcedony found to side, are continued in the other parts hanging down in these hollows, and of the pebble in a curved form. When the coats regularly formed round they appear wholly consisting of them, as the coats of wax or tallow straight lines, it may perhaps be acare round the wick in the process of counted for, from the whole mass candle-making. In the centre of taking a disposition to congeal, at the these, and in their longitudinal di- same time, that one mode of formarection, we generally find à black tion prevails throughout, as we see line, and frequently some more pro- in some jaspers where sometimes jecting part of the substance of the stars prevail, and sometimes arbo

rization. It might be supposed al- a farther use of amygdaloid rock, by so, in some measure, owing to the finding occasionally buried in its subgradual process of deposition, were stance certain regular hard bodies which we to suppose the main mass or abound also in many other rocks ; matrix to be at rest. But, if we and, from putting circumstances tosuppose fire to have been the cause gether, we shall be enabled to infer, of the Auidity of these pebble rocks, that the same formal cause has given motion is generally a concomitant rise to all of them. Thus, from a circumstance of fluidity; and we single specimen, well understood, and are therefore at liberty to suppose, taken with its consequences, a whole not merely the motion of the main theory would flow, or might be colmass concerned, which was checked lected. It appears, that, in the coonly by its congealing, but also no loured agates, in consequence of the small share of intestine motion, from change from a fluid to a solid state, the fresh union and disunion, were those colours have been separated init only the mechanical mixture of to distinct layers, which we are to such heterogeneous substances as a suppose were before diffused through bound in these rocks. A regular pro- the whole mass, and that, in consecess of deposition may, therefore, quence of that change, whether prohave been interrupted when half fi- duced by the subduction of fire, (i. e, nished, and the matter afterwards the gradual cooling of the matrix,) or compelled to arrange itself according any other cause of induration, the coto the more confined form of the hol- louring matter has been separated, low, producing the appearances which layer after layer, sometimes to a very more generally take place. There ap- minute division; and we frequently pears also in these regularly stratified find different layers of the same copebbles another mark of slow indura- lour disposed at unequal distances tion, i. e. the stellar or spherical for- from the outward surface, so that it mation of some of its parts. When appears that the central matter, which ther any principle of repulsion may was the last indurated, seems to have have hail its share in their formation, been of the same nature with the exit does not seem probable that we shall ternal or first indurated. Sometimes ever be able to determine. It may be we find these hollows filled almost observed, that, according as the mass wholly with the pure matter of quartz, is of coarser or finer materials, so is which, if there is any void space, the regularity or sphericity of these, crystallizes ; and it seems as if, after whether pebbles or mere hollows. An all the colouring matter of an agate accurate knowledge of these rocks, has been deposited in successive layand of the structure of an agate, will ers, that the matter of quartz remains do more towards explaining the great colourless, and crystallizes in the cenphenomena of Nature than any other tre. The colouring particles, if exaprinciple we can adopt. The forma- mined with a microscope, and also tion of an agate, depending upon the sometimes to the naked eye, appear in simple laws of attraction between si- the form of little spheres, according milar particles, when left at liberty to to the laws of fuids before mention follow that attraction, may be extend- ed. ed to masses of matter of any magni Those cavities which contain a vatude; and, were we to suppose the riety of substances exhibit, therefore, whole globe of our earth perfectly when any void space is left, some of fluid, either from fiery fusion or me the most perfect crystals in their holchanical suspension of its parts in wa- lows; and the same may be observed ter, it is obvious that an arrangement of the most hollow or freest parts of would take place of its particles, simi- veins, whether filled by earths or me-. lar in form, and opposite in the man tallic matter. It will admit of a quesner, the centripetal force, causing tion, whether these substances in different strata to be arranged round cooling may not contract, and thus a centre or nucleus. Thus it is that tend to produce these central cavities. spheres are formed every day upon a A probable cause of the separation of sinaller scale ; and magnitude is not the colouring matter is the cooling of concerned with either chemical or that fluid, which before held them in physical operations. We shall make solution.

VOLI

3 M

REVIEW OF NEW PUBLICATIONS.

The Border Antiquities of England and fined to the mere exploits of maraud

Scotland ; comprising Specimens of ing warfare ; gallantry and attachArchitecture and Sculpture, and o ment to the fair sex had found a ther Vestiges of Former Ages, ac- place in these rude breasts; and in such companied by Descriptions. Toge- unsettled and boisterous times, the ther with Illustrations of remarkable alarms, perils, and disasters, to which incidents in Border History and Tra- the fair objects of their admiration dition, and Original Poetry. By were perpetually exposed, afforded inWalter Scott, Esq. 2 vols. quar- cidents which it required only a noto, 1814 and 1817. London, Long- derate share of invention to weave inman and Co.

to an interesting and poetic narrative.

Another effect of this constant state Of the different regions into which of warfare upon the Borders, was the our country is divided, it may be said, construction of “ towers of defence," that, as the Highlands possess the which, if they could not aspire to the greatest attraction for the lover of na- rank of fortresses, might at least afture in her sublimest and most inter- ford protection against sudden inroad; esting forms, so the Border has charms and, if they could not repel an invadto fascinate all those who delight in er, might retard his progress. These romantic enterprise, and poetic fan- could not, indeed, rival the pomp and cy. This boundary between two war- magnificence of those mansions which, like ånd long hostile kingdoms, be- in the interior of Scotland, and the came naturally the great theatre on less troubled districts of England, which the achievements of the feudal were erected by the great nobles for ages were performed. The habitual the display of baronial splendour. A hostility, too, with which the inhabic square tower built on a height, with tants of the opposite side of the walls of immense thickness, and a few March viewed each other, gave rise narrow loop-holes for the admission of to a constant series of minor exploits, light, and the discharge of missile which, though they could not find a

weapons, formed usually the whole place in history, kept alive the habits array of a Border castle. Some, howof activity, enterprise, and daring va ever, belonging to the great nobility, lour, and held men's minds in a state were built on a scale of greater magof perpetual excitement. The same nificence; they are placed generally in causes which rendered this spot the a picturesque situation, and all of them theatre of war, rendered it also a land recal events in history and tradition of song; for true and native poetry is which must be interesting to a large the result, not of monastic and studi, portion of the present generation. It ous seclusion, but of those eventful is well, therefore, in this age of gracircumstances which fire the imagina- phic ornament, when it seems destintion, and melt the heart. It is evidented that every thing on which the eye that the flame, which animates the ge can look, must be embodied by the nius of our great Scottish minstrel, has graver, and collected into handsome been kindled at the recollection of the volumes for the amusement of the deeds of his forefathers. Had not the amateur, that these monuments of splendour of his own effusions so far the prowess of our forefathers should eclipsed those of the nameless bards not escape delineation. Besides the whose works he has with kindred military, ecclesiastical monuments of sympathy collected, these last, perhaps, considerable interest here present might have held a higher place in our themselves. These wild spirits, amid estimation ; and, even as they stand, their devotion to fight and plunder, when due allowances are made, they did not remain insensible to the incertainly appear entitled to hold no fluence of a faith so calculated to mean rank among the poetic monu dazzle the senses as that of Rome. ments of the feudal ages. The ad- The sword and the breviary went Fentures which they relate are not con- hand in hand, and the spoils of Eng.

land were partly employed in the tries, though no longer hostile, inerection of religious houses, for the duces the inhabitants of each to checelebration, with due pomp, of the rish their separate traditions,-unite Catholic rites.

to render these regions interesting to The present work, certainly, does the topographical historian or anticredit to those by whom it was pro- quary:

He then describes the anjected and executed. The different tiquities of the Britons, of which the plates appear to be well designed and most remarkable are the extensive enengraved, and the points of view in trenchments known by the name of general happily chosen. We were the Catrail, and the remains of an irparticularly pleased with the castles regular hill fort, situated on the of Newcastle, Carlisle, Warkworth, grounds of Mr Pringle of Fairnilee. Bamborough, Naworth; the monas- This is followed by a view of the Roteries of Lanercost, Tynemouth, Jed- man antiquities, which, besides their burgh, Lindisfarne. Melrose is fa- great roads, and the remains of the miliar to us on a more satisfactory wall of Antoninus, consist chiefly of scale than the present work admits. arms and sepulchral monuments. At Several of the interiors appear to us length the time came when the Saxvery interesting, and deeply impres- ons, partly as conquerors, and partly sed with that pleasing sentiment as refugees, filled the whole low counwhich carries us back into the inmost try of Scotland, and finally commurecollection of past ages.

nicated their language to that part of We think the work, however, the kingdom. Our author, however, would have been improved, if some observes, that the system of clanship kind of arrangement had been fol- which was originally Celtic, and unlowed. At first, indeed, an attempt known to the Saxons, was borrowed seems to be made at this; but it is by the latter, and adopted on the Bore soon abandoned, and the objects are ders to nearly as great an extent as in heaped together in utter confusion. the Highlands. °of this remarkable We are aware, that, in a periodical form of political association, a very work, some regard might be necessary striking picture is given. The most to the varying degree of dispatch af- flourishing period of Border history forded by the different artists. But, was the reign of David I. when the with a little good management, it splendid monasteries of Kelso, Jedmight surely have been so arranged, burgh, Melrose, and Dryburgh, were that, at the conclusion of the whole, founded. The castles also of Rox. the chaos might have been unravel- burgh and Jedburgh, then standing, led, and some systein of order esta- appear to have surpassed any military blished.

stations erected in later times. After To this work is prefixed an intro- the usurpation of Edward I. and the duction of considerable length, and succession of desolating invasions with of very peculiar value and interest. which Scotland was afflicted, the We need only mention, that it comes Scots ceased attempting to defend refrom the pen of Mr Scott, and that gularly their frontiers. The conseit contains illustrations of remarkable quences are thus described : incidents in Border history and tradi

" It followed, from this devastating systion, to satisfy the reader, that they

tem of defensive war, that the Scottish will be described at once with histori

were so far from desiring to cover their bor. cal accuracy, and with that poetic ders by building strong places or fortresses, feeling which gives them their chief that they pulled them down and destroyed interest. Mr Scott begins by remark- them where they already existed. Buchaning the striking aspect presented by a an has elegantly turned this systematic country which, after having long been destruction of their castles into a complithe theatre of national hostility, has ment to the valour of his countrymen; remained for some time in a state of

Nec fossis et muris patriam sed Marte tueri. peace.

“ Numerous castles left to moulder in massive ruins ; fields But, without disparaging Scottish valour,

the motive of leaving their frontier thus where the memory of ancient battles

open, seems to have been a consciousness still lives among the descendants of that they were greatly surpassed by the those by whom they were fought or English both in the attack and defence of witnessed; the very line of demarca- their strongholds ;-that if they threw their tion which, separating the two coune best warriors into frontier garrisons, the

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