The Useful Arts Employed in the Construction of Dwelling Houses. Second Edition

by Anonymous

The Commissioners soon had striking proofs of the necessity and importance of this inquiry in the lamentable effects of decomposition observable in the greater part of the limestone employed at Oxford; in the magnesian limestones of the Minster, churches, and other public edifices at York; and in the sandstones of which the churches and other public buildings at Derby and Newcastle are constructed; and numerous other examples. The unequal state of preservation of many buildings, often produced by the varied quality of the stone employed in them, although it may have been taken from the same quarry, showed the propriety of a minute examination of the quarries themselves, in order to gain a proper knowledge of the particular beds from whence the different varieties have been obtained. An inspection of quarries was also desirable for the purpose of ascertaining their power of supply, and other important matters; for it frequently happens, that the best stone in quarries is often neglected, or only partially worked, in consequence of the cost of laying bare, and removing those beds with which it may be associated; whence it happens, that the inferior material is in such cases supplied.

Stone buildings decay more rapidly in towns than in the open country, where dense smoke, fogs, and vapours, which act injuriously on buildings, do not exist. There is also another curious cause which contributes to the durability of stone buildings situated in the country. In the course of time, the stone becomes covered with minute lichens, which, though in themselves decomposing agents, act with extreme slowness, and when once firmly established over the entire surface of the stone, seem to exercise a protective influence, by defending the surface from the more violent destructive agents; whereas, in populous smoky towns, these lichens are prevented from forming, and thus the stone is exposed to severer trials than stone of the same kind situated in the country.

As a remarkable illustration of the difference in the degree of durability in the same material, subjected to the effects of the air in town and country, the appearance is noticed of several frusta of columns, and other blocks of stone, that were quarried at the time of the erection of St. Paul’s Cathedral, London, and which are now lying in the Isle of Portland, near the quarries from whence they were obtained. These blocks are invariably found to be covered with lichens, and, although they have been exposed to all the vicissitudes of a marine atmosphere for more than one hundred and fifty years, they still exhibit beneath the lichens their original form, even to the marks of the chisel employed upon them; whilst the stone which was taken from the same quarries, (selected no doubt with equal, if not greater care, than the blocks alluded to,) and placed in the Cathedral itself, is, in those parts which are exposed to the south and south-west winds, found, in some instances, to be fast mouldering away.

Colour is more important in the selection of a building-stone to be situated in a populous and smoky town, than for one to be placed in the open country, where all edifices become covered with lichens; for, although in such towns, those fronts which are not exposed to the prevailing winds and rains, will soon become blackened, the remainder of the building will constantly exhibit a tint depending upon the natural colour of the stone.

The chemical action of the atmosphere produces a change in the entire matter of the limestones, and in the cementing substance of sandstones, according to the amount of surface exposed to it. The particles of the stone first loosened by the action of frost are removed by powerful winds and driving rains. The buildings in this climate were generally found to suffer the greatest amount of decomposition on their south, south-west, and west fronts, arising doubtless from the prevalence of winds and rains from those quarters.

Those buildings which are highly decorated, such as the churches of the Norman and pointed styles of architecture, generally afford a more severe test of the durability of a building-stone, than the more simple and less decorated castles of the fourteenth and fifteenth centuries; because, in the former class of buildings, the stone is worked into more disadvantageous forms than in the latter, as regards exposure to the effects of the weather. Buildings in a state of ruin, from being deprived of their ordinary protection of roofing, glazing of windows, &c., afford an equally severe test of the durability of the stone employed in them.

The durability of various building-stones in particular localities was estimated by examining the condition of the neighbouring buildings constructed of them. Among sandstone buildings was noticed the remains of Ecclestone Abbey, of the thirteenth century, near Barnard Castle, constructed of a stone closely resembling that of the Stenton quarry, in the vicinity, in which the mouldings and other decorations were in excellent condition. The circular keep of Barnard Castle, apparently also built of the same material, is in fine preservation. Tintern Abbey is noticed as a sandstone edifice, that has to a considerable extent resisted decomposition. Some portions of Whitby Abbey are fast yielding to the effects of the atmosphere. The older portions of Ripon Cathedral; Rievaulx Abbey; and the Norman keep of Richmond Castle, in Yorkshire, are all examples of sandstone buildings, in tolerably fair preservation.

Of sandstone edifices in an advanced state of decomposition, are enumerated Durham Cathedral, the churches at Newcastle-upon-Tyne, Carlisle Cathedral, Kirkstall Abbey, and Fountain’s Abbey. The sandstone churches of Derby are also extremely decomposed; and the church of St. Peter, at Shaftsbury, is in such a state of decay, that some portions of the building are only prevented from falling by means of iron ties.

The choir of Southwell Church, of the twelfth century, affords an instance of the durability of a magnesio-calciferous sandstone after long exposure to the influences of the atmosphere. The Norman portions of this church are also constructed of magnesian limestone, similar to that of Bolsover Moor, and which are throughout in a perfect state, the mouldings and carved enrichments being as sharp as when first executed. The following buildings, also of magnesian limestone, are either in perfect preservation, or exhibit only slight traces of decay: the keep of Koningsburgh Castle; the church at Hemingborough, of the fifteenth century; Tickhill Church, of the same date; Huddlestone Hall, of the sixteenth century; Roche Abbey, of the thirteenth century.

The magnesian limestone buildings which were found in a more advanced state of decay, were the churches at York, and a large portion of the Minster, Howden Church, Doncaster Old Church, and buildings in other parts of the county, many of which are so much decomposed, that the mouldings, carvings, &c., are often entirely effaced.