Изображения страниц


These pieces have a shining silvery aspect; they are and hurry them down the river; until being stopped by dispersed, at first irregularly, in small numbers, but the flow of the tide, they became closely compacted to increase, both in size and numbers, till the whole gether, and agglutinated by the frost, by which means bottom is covered, and if the frost continues severe, great obstacles are presented to navigation. A curious grow in height, but in a very irregular manner, so as example of the formation of the ground-ice was reared to obliterate the earlier somewhat symmetrical shapes, to Mr. Eisdale by a miller in the western part of Scottill the streams are raised high above their former land. During a severe frost, when the mill-lead was levels, and frequently made to overflow their banks. entirely free from any kind of ice, the miller had occa

The name applied to the ground-ice to which thesion one day to lop some branches from a tree which above description refers, is a better one even than that overhung the lead; one of them fell into the water, and of the Germans. In a district where it occurs almost was left there, as he did not apprehend any ill conseevery winter, and often repeatedly during that season, quences from so trifling an occurrence. Next day, howand where many of the rivers are crossed by means of ever, to his astonishment, the water was turned entirely fords, its existence influences too much their economical out of the lead, and had overflowed a large portion of arrangements not to excite their particular attention, an adjoining meadow. On proceeding to ascertain the especially as many horses refuse to enter any stream cause, he found that a solid barrier of ice had been even slightly impeded by it, being greatly alarmed by formed across the lead, where the branch had fallen the pieces which break and float up from the bottom by in, so as completely to prevent any water from passing, the action of their feet. A substance with which all whilst the rest of the lead was free from ice. are so well acquainted, is known by an appropriate Mr. Knight, the celebrated botanist, has related an

It is called ground-gru; gru being the term observation which is the more valuable, as it seems in applied to snow saturated with, or swimming in, water. some respects to afford a clue to the secret of the for

The formation of ground-gru occurs only when the mation of ice in the bottom of rivers; he says :temperature of the whole mass of water is reduced to, I first witnessed the existence of ice in the bottom of or nearly to, 32°, the temperature of the air being the water in the river Teme, which passes near my resiseveral degrees below that point. It is preceded by a

dence in Herefordshire. In a morning which succeeded continuance for some time of a clear state of the sky. the river appeared to be covered over with frozen matter,

an intensely cold night, the stones in the rocky bed of But while forming under the continuance of a cloudless which reflected a kind of silvery whiteness, and which sky, its increase is impeded during the day, but when a upon examination, I found to consist of numerous frozen densely clouded state of the sky occurs, and continues spicula, crossing each other in every direction, as in snow, for twenty-four hours, the gru becomes detached from but not having anywhere, except very near the shore, the bottom, and floats down the stream. Should the assumed the state of firin compact ice. The river was not temperature of the air continue low, with a clouded sky, at this time frozen over in any part; but the temperature or get lower, the ground-gru is not renewed, but the of the water was obviously at the freezing-point, for small river is speedily frozen over at the surface. In fact, it

pieces of ice had everywhere formed upon it in its more

stagnant parts near the shores; and upou a mill-pond, just frequently occurs in frosty winters, that the rivers, above the shallow stream (in the bottom of which I had filled and so impeded by ground-gru, as to be raised observed the ice), I noticed millions of little frozen spicula above their banks, are found returned into their natural floating upon the water. At the end of this mill-pond the channels, and there frozen over at the surface, but flow water fell over low weir, and entered a narrow channel, ing over a clear bottom, in a space of time so short as where its course was obstructed by points of rock and large to appear very wonderful to those who have not inves stones. By these, numerous eddies and gyrations were tigated the cause. The process is named, by the occasioned, which apparently drew the foating spicula

under water; and I found the frozen matter to accumulate country people, the flitting of the ice.

much more abundantly upon such parts of these stones as Some interesting observations on the same subject stood opposed to the current, where that was not very rapid, were made by the Rev. Mr. Eisdale, and read by him below the little falls or very rapid parts of the river. I before the Philosophical Society of Perth, in December, have reason to believe that it would have accumulated in 1831, being subsequently communicated 10 JAMESON's very large quantities if the weather had continued suffiNew Edinburgh Philosophical Journal. From thence ciently cold; for I had previously heard from persons of we gain the following particulars. Ground-ice, as ob respectable character, who had no interest, nor, I believe, served by Mr. Eisdale, is produced only in the most

intention to deceive me, that during a long and severe frost rapid and rugged streams: it commences at the bottom

some years ago, before I became an inhabitant of my pre

sent house, the whole bed of the river in the part aboveof the water, and extends upwards to the surface. He mentioned had been covered over with a thick coat of ice. speaks of that kind of ice as being well known in all | But it was not till the month of February that I witnessed northern climates from its annoying effects in obstruct- the apparent deposition of ice in the manner which I have ing all works which are carried on by the impelling described; and as the day afterwards became bright, the power of water. When ice collects on the surface of spicula soon ceased to form, and the ice to accumulate; and mill-streams, it is easily managed and broken up, but

before the middle of the day the greater part of it had diswhen ground-ice forms, the case is perfectly hopeless,


Upon some large stones near the shore, of which parts the streams being obstructed and gorged up from the

were out of the water, and upon pieces of native rock, very bottom. This kind of ice is called in the south of under similar circumstances, the ice beneath the water had Scotland clappered ice," an epithet which the common acquired a firmer texture, but appeared from its whiteness people apply to the natural coagulation of milk. to have been first formed of congregated spicula, and to The first appearance of this ice at Perth occurs on

have subsequently frozen into a firm mass, owing to the the setting-in of a severe frost, before the true ice has lower temperature of the stone or rock. Ice of this kind made much progress in advancing from the sides to and lay three or four inches from the level of the surface

extended in a few places, eighteen inches from the shore, the centre of the river: nearly the whole body of the of the water, and did not dissolve near so rapidly as stream above the bridge is then occupied by large irre- that which was deposited upon stones more distant from gular masses of floating ice of very considerable thick- the shores. ness, far beyond anything that could be effected by The fact, of which the above instances give abundant the natural operation of the frost in surface freezings. evidence, had been noticed by fishermen and others, These masses are formed in the most rugged currents, long before it became the subject of discussion with adhering to the projecting rocks, and rough inequalities scientific men. at the bottom, and increasing upwards, till their bulk In the year 1730, when the atmosphere was at the and smaller specific gravity as compared with water, temperature of nearly 16° Fahr., a person named Hales enable the stream to tear ihem from their fastenings. saw at Teddington, the surface of the Thames, near the

[ocr errors][ocr errors]

banks, covered with a layer of ice one third of an inch Queen has the powers of all the other pieces except the in thickness. There was also at the same time, a Knight, it is not necessary to choose a Bishop or a Rook ; second layer below, of greater thickness, which fol- but that it may be desirable to choose a Knight on lowed the depth of the river, as it adhered to the account of his peculiar checking power. We have been bottom. This sheet was united to the upper one, even reminded by a correspondent, Mr. E. J. Catlow, that it on the water-side ; but it was graduaily separated in may happen that the player advancing his pawn to the proportion, as, in proceeding into the river, the depth eighth square and claiming a Queen, would stale-mate of the water increased. It was not solid as the first, his adversary; while by claiming a Bishop in one case, and was mixed with sand, and even stones, which the and a Rook in another, he may win the game. Our corflakes sometimes carried with them in their movement respondent has invented two such positions, which are upwards.

given below. It will be seen from the solutions that in A few more instances of the occurrence of ground- either case it is possible to have too much mating power ; ice in rivers, and the mode in which the circumstance is for the Queen, combining the moves of the Bishop and explained by scientific men, will be given on another the Rook, leaves no move to the adverse King, and conoccasion.

sequently he is stale-mated.

1. White to move, and to check-mate in two moves.


The spirit of domestic peace,
Though calm and gentle as the brooding dove
And ever murmuring forth a quiet song,
Guards powerful as the sword of Cherubim,
The hallowed porch. She hath an heavenly smile,
That sinks into the sullen soul of vice,
And wins him o'er to virtue.-WILSON,

[ocr errors]

WHERE there are no roads there are always many ways.

[ocr errors]

1. P. to K. B. eighth sq., becoming a

2. R. to K. R. sixth sq. check-mate.

1. K. to K. R. sq.

Among the fathers of the Arabian philosophy may be numbered Honain, an eminent Christian physician, who translated the Elements of Euclid, and other Greek authors, into Arabic. He flourished in the ninth century, under the caliph Al-Mamon, who was not only an illustrious patron of learning, but was himself no mean adept in several branches of science.

One day, after some medical conversation, the caliph said to Honain, “ Teach me a prescription by which I may take off any enemy I please, without being discovered.” Konain declining to give an answer, and pleading ignorance, was imprisoned. Being brought again, after a year's interval, into the caliph's presence, and still persisting in ignorance, though threatened with death, the caliph smiled upon him, and said, “Be of good cheer, we were only trying thee, that we might have the greater confidence in thee." As Honain upon this bowed down and kissed the earth, “What hindered thee,” said the caliph, “from granting our request, when thou sawest us appear so ready to perform what we threatened ?” “Two things," replied Honain;“my religion and my profession. My religion, which commands me to do good to my enemies; and my profession, which was purely instituted for the benefit of mankind.” “ Two noble laws!” said the caliph; and immediately presented him, according to the eastern usage, with rich garments, and a sum of money As many natural bodies, whilst they are still entire, are corrupted and putrefy, so the solid knowledge of things often degenerates into subtile, vain, and silly speculations, which, although they may not seem altogether destitute of ingenuity, are insipid and use ess. This kind of unsound learning, which preys upon itself, has often appeared among men who have much leisure, quick parts, and little reading; and being, moreover, in a great measure, ignorant of the history both of nature and of the world; out of very flimsy materials, but with the most rapid and violent motion of the shuttle of thought, they have woven those laborious webs which are preserved in their writings. The truth is, that the human mind, when it is employed upon external objects, is directed in its operations by the nature of the materials upon which its faculties are exercised : but if, like the spider, it draws its materials from within itself, it produces cobwebs of learning, wonderful indeed for the fineness of the threads, and the delicacy of the workmanship, but of no real value or use.—LORD Bacon.

II. White to move, and to check-mate in two moves.


CHESS. In our recent notice of the solution of M. Calvi's problem *, it was stated that when a pawn arrived at its eighth square it is sometimes necessary to exchange it for some other piece than a Queen; but that, as the

• See Saturday Magasine, Vol XXIII., pp. 192 and 268

1. P. to Q. B. eighth sq., becoming a

2. R. to Q. R. eighth sq., check-mate.

1. K. to Q. R. third sq.


THE BERLIN CAST-IRON ORNAMENTS. made of native material, and exported in large quanOne of the most interesting establishments in the city

tities abroad, and even, indeed, to America. This of Berlin is the Iron Foundry, at which are cast the

branch of native industry, however, has been greatly celebrated black iron trinkets commonly called Berlin

injured by the extensive imitation of the articles, and

the sale of them at a cheaper rate. The facility of This manufacture originated at the time of the com

imitation of the most saleable objects, by purchasing mencement of the final struggle between Prussia and

them at a low price, using them as models, and then Napoleon. The country, impoverished by long and casting articles of the same description, enables the unsuccessful wars, was enabled to cope with her

imitator to offer his goods at such a low price that the oppressor chiefly by the patriotism of her sons who original manufacturer, who has been at the expense of yielded their active services, and of her daughters who, much time and capital in the designing and forming a with a noble generosity, sent their jewels and trinkets

brass model, finds it impossible to enter into competo the royal treasury. Those who made this sacrifice

tition with him. So that the manufacturer not ventur. received in return rings, crosses, and other ornaments,

ing to expend much capital on new models, which do in cast-iron, which bore the inscription, Ich gab Guld

not repay the outlay, the articles by repeated castings um Eisen: “I gave gold for iron :” and to the present

lose much of their sharpness and beauty, and the day these articles are much valued by the possessors

natural consequence is that their reputation abroad is and their families.

injured, and, notwithstanding the moderate prices, the Strangers are freely admitted to the Iron Foundry to

sale must decline. On this account some of the first see the casting, which usually takes place in the even

manufacturers have given up the business, and the task ing. The castings are not, however, confined to of improving and perfecting this branch of industry trinkets; busts, statues, bas-reliefs, copies of pictures,

now rests in the hands of a few. monumental slabs, &c., are cast with equal success; for

Dr. Friedenberg's account of the deterioration of this whether the object caet be a colossal statue, or the

interesting branch of manufacture is verified by expe. minute filagree ornaments of a lady's toilet, the casting

rience. We have recently inspected some cast-iron cannot be equalled in delicacy and fineness of impres

ornamental articles from Berlin, and found them en. sion in any other part of Europe. It is said that this tirely deficient in that sharpness of outline and preexcellence is due to the quality of the Silesian iron;

cision of form for which they were once celebrated. others attribute it to the care bestowed on the moulds, which are formed of a very fine sand mixed with a small portion of clay.

EFFECTS OF A SOLAR ECLIPSE ON ANIMALS. Dr. Friedenberg, in his translation into German of In his report on the eclipse of July 8th, 1842, M. Arago Mr. Babbage's work on the Economy of Manufactures, always disbelieved that a friend of his put five healthy and

mentions, in support of a popular notion which he had mentions the Berlin cast-iron ornaments as an inter

lively linnets in a cage together, and fed them immediately esting example of the increased value of manufactured

before the eclipse. At the end of it three of them were articles in comparison with the raw material.

found dead. Other indications of the alarm it produced In one of the principal manufactures of these orna were seen in a dog which had long been kept fasting, and ments, such is the fineness and delicacy of those sepa which was eating hungrily when the eclipse commenced, rate arabesques, rosettes, medallions, &c., of which the but left his food as soon as the darkness set in. A colony larger ornaments are composed, that it requires nearly

of ants which had been working actively, suddenly ceased ten thousand of them to make up a pound weight.

from their labours at the same moment. The price increases in proportion to the fineness, as will be seen by the following table, which gives the ON THE DURABILITY OF STONE prices of one eminent Berlin manufacturer.


On the Choice Of A Stone for BUILDING

PURPOSES. 1. Buckles, 34 inches long and 2} inches

EVERYTHING belonging to the earth, whether in its primi2,640

tive state, or modified by human hands, is submitted to 2. Neck-chains, 18 inches long and I

certain and innumerable laws of destruction, as permanent inch broadl, and composed of 40 2,310

693 0 0 and universal as those which produce the planetary motions. separate pieces 3. Bracelets, 7 inches long and 2 inches ll 2,090

The operations of nature, when slow, are no less sure; broad, and composed of 72 pieces

5 0 [pair.

however man may for a time usurp dominion over her she 4. Diadems, 74 inches high and 54 inches broad į 1,100 100

is certain of recovering her empire. He converts her rocks, 907 10 0

her stones, her trees, into forms of palaces, houses, and 5. Sevignė needles, 24 inches long and

ships; he employs the metals found in the bosom of the 14 inches broad, and composed of 9,020

Namber to
the cw.

Price of

each article.

Price per cwt.
of the same.

8. d.
2 6

£ 330

[ocr errors]


6 0

8 6


4 6

2029 100

earth as instruments of power, and the sands and clays 6. Sevigné ear-rings, 3 inches long and

which constitute its surface as ornaments and resources of f of an inch broad, and composed of


6 3 2743 2 6 luxury; he imprisons air by water, and tortures water by (pair.

fire to change, to modify, or destroy the natural forms of 7. Shirt buttops

88,440 08 2948 0 0 things. But in some lustrums his works begin to change,

and in a few centuries they decay and are in ruins; and liis Taking the price of the grey iron, from which these mighty temples, framed, as it were, for divine purposes, ornaments are made, at 6s. per cwt., on an average, the

and his bridges formed of granite, and ribbed with iron, value of the material is increased 1100 times in the

and his walls for defence, and the splendid monuments by

which he has endeavoured to give eternity even to its coarser articles, and 9827 times in the finest. The above are the retail prices, and wholesale prices structures which have resisted the waves of the ocean, the

perishable remains, are gradually destroyed; and these are probably one-sixth or one-eighth less.

tempest of the sky, and the stroke of the lightning, shall pared with old prices the present ones are much yield to the operation of the dews of heaven, of frost, rain, reduced. About the year 1827 they were twice as

vapour, and imperceptible atmospheric influences; and as high, and about the year 1820 three times, so that at

the worm devours the lineaments of his mortal beauty, so that time Berlin cast iron was nearly of equal value

the lichens and the moss, and the most insignificant plants, with gold,-a remarkable example, and, perhaps, one of humble and insignificant insects shall undermine and sap

shall feed upon his columns and his pyramids, and the inost the strongest proofs of the influence of the industry of

the foundations of his colossal works, and make their habis manufacturers on the wealth of the state, especially tations amongst the ruins of his palaces, and the falling when we consider that the cast-iron ornaments are seats of his earthly glory. Sir Humphrey Davy,

ll parts

24 pieces

But com

Although it is true that all human works must decay, populous smoky towns, these lichens are prevented from yet it is a point of great importance to ourselves and forming, and thus the stone is exposed to severer trials our successors whether that decay be slow or speedy. than stone of the same kind situated in the country. The causes enumerated in the above eloquent passage,

As a remarkable illustration of the difference in the though sure, are exceedingly slow in their action, and degree of durability in the same material, subjected to provided the building materials have been selected with the effects of the air in town and country, the appearreference as well to their durability as to their beauty, ance. is noticed of several frusta of columns, and other the resulting structure may defy the corroding tooth of blocks of stone, that were quarried at the time of the time for many ages, and we may thus transmit to a long erection of St. Paul's Cathedral, London, and which are posterity, lasting memorials of our wisdom and science, now lying in the Isle of Portland, near the quarries from as well as of our piety. Modern science has to a very whence they were obtained. These blocks are invariably great extent enabled the architect and builder to deter- found to be covered with lichens, and, although they have mine beforehand what is the durability of any given been exposed to all the vicissitudes of a marine atmostone, and it is with great pleasure that we now notice sphere for more than one hundred and fifty years, they the extensive inquiry made at the suggestion of Mr. still exhibit beneath the lichens their original form, even Barry, the architect of the new Houses of Parliament, to the marks of the chisel employed upon them; whilst under the Commission issued by Her Majesty's Govern- the stone which was taken from the same quarries, (sement, to investigate the qualities of stone in various lected no doubt with equal, if not greater care, than the parts of the kingdom, in order to select that which blocks alluded to,) and placed in the Cathedral itself, should best ensure perpetuity to this grand national is, in those parts which are exposed to the south, and monument. This commission, consisting of Mr. Barry, south-west winds, found, in some instances, to be fast Sir H. T. De la Beche, Dr. W. Smith, and Mr. C. H. mouldering away. Smith, visited one hundred and five quarries, and exa Colour is more important in the selection of a build. mined one hundred and seventy-five edifices; and their ing stone to be situated in a populous and smoky town, collected specimens were then submitted to tests, both than for one to be placed in the open country, where all mechanical and chemical, by Professors Daniell and edifices become covered with lichens; for, although in Wheatstone, of King's College, London. In order to such towns, those fronts which are not exposed to the leave a permanent record of their labours, the Commis- prevailing winds and rains, will soon become blackened, sioners published a Report, and deposited in the Museum the remainder of the building will constantly exhibit a of Economic Geology, a variety of specimens of the tint depending upon the natural colour of the stone. stones which they had collected. From this Report, we The chemical action of the atmosphere produces a select such details as are calculated to serve the purposes change in the entire matter of the limestones, and in of popular instruction.

the cementing substance of sandstones, according to the The Commissioners did not consider it necessary to amount of surface exposed to it. The particles of the extend their inquiries to granites, porphyries, and other stone first loosened by the action of frost are removed stones of similar character, on account of the enormous by powerful winds and driving rains. The buildings in expense of converting them to building purposes in this climate were generally found to suffer the greatest decorated edifices, and from a conviction that an equally amount of decomposition on their south, south-west, and durable, and in other respects more eligible material, west fronts, arising doubtless from the prevalence of could be obtained for the object in view from among the winds and rains from those quarters. limestones or sandstones of the kingdom.

Those buildings which are highly decorated, such as The Commissioners soon had striking proofs of the the churches of the Norman, and pointed styles of necessity and importance of this inquiry in the lament- architecture, generally afford a more severe test of the able effects of decomposition observable in the greater durability of a building stone, than the more simple and part of the limestone employed at Oxford; in the mag less decorated castles of the fourteenth and fifteenth nesian limestones of the Minster, the other churches, centuries; because, in the former class of buildings, the and public buildings at York; and in the sandstones stone is worked into more disadvantageous forms than of which the churches and other public edifices at in the latter, as regards exposure to the effects of the Derby and Newcastle are constructed; and numerous weather. Buildings in a state of ruin, from being other examples. The unequal state of preservation of deprived of their ordinary protection of roofing, glazing many buildings often produced by the varied quality of of windows, &c., afford an equally severe test of the the stone employed in them, although it may have been durability of the stone employed in them. taken from the same quarry, showed the propriety of a The durability of various building stones in particular minute examination of the quarries themselves, in order localities was estimated by examining the condition of to gain a proper knowledge of the particular beds from the neighbouring buildings constructed of them. Among whence the different varieties have been obtained. An sandstone buildings were noticed the remains of Eccleinspection of quarries was also desirable for the purpose stone Abbey, of the thirteenth century, near Barnard of ascertaining their power of supply, and other impor- Castle, constructed of a stone closely resembling that of tant matters; for it frequently happens, that the best the Stenton quarry, in the vicinity, in which the mouldstone in quarries is neglected, or only partially worked, ings and other decorations were in excellent condition. in consequence of the cost of laying bare, and removing the circular keep of Barnard Castle, apparently also those beds with which it may be associated; whence it built of the same material, is in fine preservation. Tinhappens, that the inferior material is in such cases sup- tern Abbey is noticed as a sandstone edifice, that has plied.

to a considerable extent resisted decomposition. Some Stone decays more rapidly in towns than in the open portions of Whitby Abbey are fast yielding to the effects country, where dense smoke, fogs, and vapours, which of the atmosphere. The older portions of Ripon act injuriously on buildings, do not exist. There is also Cathedral; Rivaulx Abbey; and the Norman keep of another curious cause which contributes to the durability Richmond Castle, in Yorkshire, are all examples of of stone buildings situated in the country. In the sandstone buildings, in tolerably fair preservation, course of time, the stone becomes covered with minute Of sandstone edifices in an advanced state of decomlichens, which, though in themselves decomposing position, are enumerated Durham Cathedral, the churches agents, act with extreme slowness, and when once firmly at Newcastle upon-Tyne, Carlisle Cathedral, Kirkstall established over the entire surface of the stone, seem to Abbey, and Fountain's Abbey. The sandstone churches exercise a protective influence, by defending the surface of Derby are also extremely decomposed; and the from the more violent destructive agents: whereas, in church of St. Peter's, at Shaftsbury, is in such a state

of decay, that some portions of the building are only | Report gives the preference to the limestones, on prevented from falling by means of iron ties.

account of their more general uniformity of tint, their The choir of Southwell Church, of the twelfth century, comparatively homogeneous structure, and the facility affords an instance of the durability of a magnesio- and economy of their conversion to building purposes; calciferous sandstone after long exposure to the influences and, of this class, preference is given to those which are of the atmosphere. The Norman portions of this most crystalline. Professor Daniell is of opinion that church are also constructed of magnesian limestone, the nearer the magnesian limestones approach to equisimilar to that of Bolsover Moor, and which are through- valent proportions of carbonate of lime and carbonate of out in a perfect state, the mouldings and carved enrich- magnesia, the more crystalline and better they are in ments being as sharp as when first executed. The every respect. following buildings, also of magnesian limestone, are It was considered that this crystalline character, either in perfect preservation, or exhibit only slight together with durability, as instanced in Southwell traces of decay; the keep of Koningsburgh Castle; the Church, &c.; uniformity in structure; facility and ecochurch at Hemingborough, of the fifteenth century; nomy in conversion; and advantage in colour, were all Tickhill Church, of the same date; Huddlestone Hall, of comprised in the magnesian limestone, or dolomite of the sixteenth century; Roche Abbey, of the thirteenth Bolsover * Moor and its neighbourhood; and this was century.

accordingly recommended as the most proper material The magnesian limestone buildings which were found to be employed in the new Houses of Parliamentt in a more advanced state of decay, were the churches at This opinion was not arrived at, nor this recommenYork, and a large portion of the Minster, Howden dation made, until after a very extensive series of expeChurch, Doncaster old church, and buildings in other riments had been completed by Professors Daniell and parts of the county, many of which are so much de- Wheatstone upon specimens of the stones of the various composed, that the mouldings, carvings, &c., are often quarries visited by the Commissioners. The specimens, entirely effaced.

as delivered to these gentlemen, were in the form of The Report speaks in high terms of the preservation two-inch cubes. These experiments were of a most of buildings constructed of colitic and other limestones; comprehensive kind. The composition of the stones such are Byland Abbey, of the twelfth century; Sandys was determined by chemical analysis :their specific foot castle, near Weymouth, constructed of Portland gravities; their weights after having been perfectly oolitic in the time of Henry the Eighth; Bow-and- dried by exposure in heated air for several days; then Arrow Castle, and the neighbouring ruins of a church their weights after having been immersed in water for of the fourteenth century, in the island of Portland. several days so as to become saturated; the object

The oolite in the vicinity of Bath does not seem to being to ascertain the absorbent powers of the stones, wear well.

which was further tested by placing them in water The excellent condition of the parts which remain of under the exhausted receiver of an air-pump. The Glastonbury Abbey shows the value of a shelly lime stones were also subjected to the process of disintegrastone similar to that of Doulting; whilst the stone tion, invented by M. Brard, the object of which is to employed in Wells Cathedral, apparently of the same determine, by easy experiments, whether a building kind, and not_selected with equal care, is in parts stone will or will not resist the action of frost. This decomposed. In Salisbury Cathedral, built of stone process is so curious and valuable that we will state from Chilmark, we have evidence of the general dura- it at length in a separate article. Lastly the cohebility of a siliciferous limestone; for, although the west sive strength of each specimen, or its resistance to front has somewhat yielded to the effects of the atmo- pressure, was tested by the weight required to crush it. sphere, the excellent condition of the building generally This weight was furnished by a hydrostatic press, the is most striking.

pump of which was one inch in diameter: one pound at The materials employed in the public buildings of the end of the pump lever produced a pressure on the Oxford afford a marked instance both of decomposition surface of the cube equal to 2.53 cwt., or to 71.06 lbs. and durability; for whilst a shelly oolite, similar to that on the square inch. These trials were made with of Taynton, which is employed in the exposed parts of caution, the weight on the lever was successively inthe more ancient parts of the Cathedral, in Merton creased by a single pound, and, in order to ensure a College Chapel, &c., is generally in a good state of gradual action, a minute was aliowed to elapse previous preservation, a calcareous stone from Heddington. em to the application of each additional weight. It was ployed in nearly all the colleges, churches, and other noted for each specimen the pressure at which the stone public buildings, is in such a deplorable state of decay began to crack, and also the pressure at which it was as, in some instances, to have caused all traces of archi- crushed. tectural decoration to disappear, and the ashler* itself The results of all these experiments (which are stated to be, in many places, deeply disintegrated.

for each stone), gave a decided preference to the Bol. In Spofforth Castle two materials, a magnesian lime sover magnesian limestone, which was noticed as being stone and a sandstone, have been employed; the former remarkable for its peculiarly beautiful crystalline strucin the decorated parts, and the latter for the ashler, and ture, while it was the heaviest and strongest of all the although both have been equally exposed, the mag- specimens, and absorbed least water. Its composition nesian limestone has remained as perfect in form as was 50 per cent of carbonate of lime, and 40 of carbon'when first employed, while the sandstone has suffered ate of magnesia; the remaining ten parts consisting considerably from the effects of decomposition. In chiefly of silica and alumina. Chepstow Castle a magnesian limestone is in fine pre'servation, and a red sandstone rapidly decaying. A * Bolsover is a small market town in Derbyshire, on the borders of the similar result was observed in Bristol Cathedral, which county of Nottingham, and about 145 miles from London.

+ The various quarries visited by the Commissioners are noticed in the afforded a curious instance of the effects of using diffe- fullest and fairest manner. They have stated for each quarry its name rent materials; for a yellow limestone and a red sand- and situation; the names and addresses of the freeholder, of his agent,

stone have been indiscriminately employed both for the weight per cubic foot; entire depth of workable stone ; description of the plain and the decorated parts of the building; not only beds; size of blocks that can be procured; prices, per cubic imt, of block is the appearance unsightly, but the architectural effect stone at the quarry; description and cost of carriage to London; cost, per of the edifice is also much impaired by the unequal | plain rubbed work, as compared with Portland stone; and, finally, where

cubic foot, of the stone delivered in London; cost, per foot of surface, of decomposition of the two materials.

known or reported to have been employed in building. After enumerating these and other examples, the • Tho ashlor is the plain facing of the walls.


« ПредыдущаяПродолжить »