Rubble stone

“ Dimension stone, flint, rubble, burnt or unburnt brick,--use them as you find them. For it is not every neighbourhood or particular locality that can have a wall built of burnt brick like that at Babylon, where there was plenty of asphalt to take the place of lime and sand, and yet possibly each may be provided with materials of equal usefulness so that out of them a faultless wall may be built to last forever. ”

“ Natural material is coming more and more to be used and we find a rubble wall, constructed from stone and boulders picked up on the grounds, left often rough, and again filled in with red cement to make it more stable. The rubble wall is generally topped with cement laid perfectly flat. The entrance posts follow this same line of treatment and while they are often left hollow for several inches down, these are packed solidly inside with small rocks to keep them in place. ”

“ It consists of placing stones on one another which on their faces are square or nearly so but which are pyramidal in shape, and come to a point at their back. They rest at their faces on the thin ledge at the front of the stone and are supported at their backs by small stones loosely inserted, und the walls so built have generally a rubble backing about three or four feet thick. ”

“ Next comes the consideration of stone-quarries from which dimension stone and supplies of rubble to be used in building are taken and brought together. ”

“ Now, two of the most important things you will have to guard against is cutting through the rough stuff and lead coats, and scratching the surface. There is a great difference in pieces of pumice stone. Some are hard and full of flint like particles, which will scratch the work; others are softer and of more even grit; the light colored and fairly open grained pieces are the safest to use. You can tell a fast cutting stone by its open grain and lightness. The finer grades of German rubbing brick and English rubbing stone are also used in rubbing rough stuff. ”

“ One kind, where the stones are loosely thrown together in a wall between boards and grouted with mortar almost like concrete, is called in Italian muraglia di getto and in French bocage. Work executed with large stones put together without any attempt at courses is also called rubble. ”

“ Other stones, such as ‘fired’ zircon, white sapphire, white topaz, and rock-crystal, may dazzle with brilliancy of light reflected from the surface or emitted from the interior, but none of them, like diamond, glow with mysterious gleams. No hint of colour, save perhaps a trace of the blue of steel, can be tolerated in stones of this category; above all is a touch of the jaundice hue of yellow abhorred. It taxes all the skill of the lapidary to assure that the disposition of the facets be such as to reveal the full splendour of the stone. ”

“ The best place, however, to true up a whetstone is upon the horizontal stone of a marble worker; this is a large grindstone, several feet in diameter, mounted on a vertical shaft, upon which are placed pieces of marble to be ground to a flat surface.
(D.) Artificial oilstones, made of emery, corundum, carborundum, and other artificial abrasives, are coming rapidly into use, and, as in the case of grindstones, eventually will supplant all others in many occupations, as they cut faster than any natural stone, may be made of any degree of fineness, and are of absolutely even texture. ”

“ Observe how light this kind of stone is, being composed of cells scarcely thicker than egg-shells. Yet, try to crush it under your heel. It resists, and the pressure scarcely blunts its asperities. Well, dry it, and in a week it will be even harder. A smart blow with a hammer will be required to break it.
“This material is perhaps the best for vaults, on account of its lightness, its toughness, its cavities, and that roughness of surface which makes the mortar adhere so closely to the joints that it cannot be separated, and the whole, when sufficiently dry, seems to form only a single piece. ”

“ If the stone is set, press a sharp corner of a broken-ended file gently against a back facet, preferably high up toward the girdle, where any damage will not be visible from the front, and move the file very slightly along the surface, noting by the feel whether or not it takes hold and also looking with a lens to see if a scratch has been made. Do not mistake a line of steel, left on a slightly rough surface, for a true scratch. ”

“ Many of the forms described by Sir William Wilde, [11] under the name of sling-stones, may also, I think, be more properly placed in some other category. The carefully polished lenticular disc of flint (Wilde, Fig. 9) seems better adapted for a cutting tool; and the flat oval stones, usually with "a slight indentation, such as might be effected by rubbing with a metal tool," were, as I have already observed, more probably used for obtaining fire, like those of the same class belonging to the early Iron Age of Denmark, [12] which they much resemble in character. ”

“ A light iron truss spanning fifty feet might be able to bear enormous weights, while an iron scantling containing four times the amount of metal would break from its own weight; but in stone buildings there is no such reserve. The engineer who constructs a roof or shed too strongly, or he whose building is wanting in strength, are both deficient in skill. Stone, however, needs no such caution. It may be used so as to possess, and appear to possess, a surplussage of strength, and yet not seem excessive, and the same may fairly be claimed for brick and oak. ”

“ The gentleman has compounded a cement or mortar, which, by the mere action of the air, assumes in a week or two the durability and consistence of the hardest marble and the firmest stone, and may be applied to all the purposes to which the strongest grained freestone is usually applied. Bridges, aqueducts, houses, and we suppose pavements and roads, can be as well constructed of this material as of the ordinary matters used in their composition. ”

“ It seems strange that in a land where trees are so abundant and timber is to be had for the trouble of felling preference should be given to granite; yet the stone is easier and cheaper to work than timber, and on the hills and roadsides men and women are constantly quarrying the brittle substance. The way of working and the tools employed are very simple. Holes are chiselled at distances of about a foot; then iron or wooden wedges are driven in and the granite block is separated. ”

“ It is an irregular oval, about seven inches in diameter, with an undulated surface, composed of about a dozen smaller stones of different sizes and shapes, well joined together with a small quantity of cement, and perfectly smooth; it looks as if the whole had been broken into many pieces by a violent blow, and then united again. It is very difficult to determine accurately the quality of this stone, which has been worn to its present surface by the millions of touches and kisses it has received. ”

“ It is not a nice material to work, being apt to check and crack in the most unlooked-for manner. To those who have never seen it, I will say that it is a stone, or species of marble, obtained in Russia, and is green in color, marked with white and greenish gray stripes. The green is specially brilliant, and the effect is very fine. Although it is so hard that steel will not cut it, it is easily scratched in use, and is a soft stone, and can be readily cut on a common vulcanite emery wheel, and polished on a razor strop covered with rouge powder. ”

“ The chipping out of celts and some other tools formed, not of flint, but of other hard rocks, must have been effected in the same manner. The stone employed is almost always of a more or less silicious nature, and such as breaks with a conchoidal fracture. ”

“ The surface should always be wet when in use both to carry off the particles of stone and steel, and thus preserve the cutting quality of the stone, and to keep the tool cool, as otherwise, its temper would be drawn, which would show by its turning blue. ”

“ The safest and indeed the most common indication of an implement being really genuine is the alteration in the structure of the flint which has taken place over the greater part, if not the whole, of its surface, and the discoloration it has undergone. In ochreous beds of gravel the specimens are frequently much stained of a yellow, buff, or brown colour; where less iron is present they become grey, especially at the angles, and often more so on one face than the other. ”

“ To those who may wish to occupy themselves with this problem these explorations have furnished, as we have just seen, a vast collection of objects made of stone, bone, horn, wood, bronze, iron, and gold.
Among the stone objects are—querns, hammer-stones, whetstones, so-called sling-stones, a few cup-marked stones (one surrounded by concentric circles) , spindle-whorls, flint flakes, and [Pg 450] scrapers, a polished celt, a perforated axe-hammer head, portions of two polished circular discs, and some oval implements with a wrought hollowed surface on each side. ”

“ As a result of long trial on roads in England and on the Continent, it is found that the stone best suited for road metal must possess toughness and cementing qualities and as great a resistance to abrasion as is possible in a stone having the first two properties. ”

“ Before proceeding to the consideration of other forms of implements, it will be well to say a few words with regard to those which have served for grinding, polishing, or sharpening tools and weapons, and more especially such as there is every reason to suppose, were employed to give an edge or finish to other materials than metal, though the whetstones of the Bronze Period must not be passed by unnoticed. ”

“ Every joint of the stone is used, in like manner, as a thin black line, which the slightest sign of cement would spoil like a blot. And so proud is the builder of his fine jointing, and so fearless of any distortion or strain spoiling the adjustment afterwards, that in one place he runs his joint quite gratuitously through a bas-relief, and gives the keystone its only sign of preëminence by the minute inlaying of the head of the Lamb into the stone of the course above. ”

“ Limestone, granite, and sandstone were used for building at a very remote period in much the same way as wood, large blocks, fresh from the quarry, of all manner of different shapes, being piled up horizontally or stood on edge, no cement being employed, though in certain cases crushed stone was used to fill up the spaces between the blocks. ”

“ An expert may obtain a fair idea of hardness by gently passing the stone over a fine steel file, and observing the feel of the stone and the grating sound which it emits. If a stone be scratched by a steel knife its hardness is below 6. The degree of hardness of a precious stone is soon ascertained by the lapidary when cutting it.
Gem-stones differ markedly among themselves in density or specific weight ”

“ In some parts of France I have seen extremely heavy iron axes, much resembling these stone implements in form, used for splitting wood. It seems possible that in old times these heavy stone implements may also have been employed in agriculture. ”

“ But the moment that the iron in the least degree takes the place of the stone, and acts by its resistance to crushing, and bears superincumbent weight, or if it acts by its own weight as a counterpoise, and so supersedes the use of pinnacles or buttresses in resisting a lateral thrust, or if, in the form of a rod or girder, it is used to do what wooden beams would have done as well, that instant the building ceases, so far as such applications of metal extend, to be true architecture. ”

“ The name of Axe is, with sufficient appropriateness, applied to the double-edged stone implements, and to those of a wedge-shape which have the aperture for inserting the handle near the broad end, whereas other examples perforated sufficiently near the centre to admit of the free use of both ends are with equal propriety styled hammers. They are frequently finished with great neatness and art; not made, like the hatchet, of flint, but of a variety of kinds of stone, from the gray granite, of which the largest are generally made, to trap and even sandstone. ”

“ Should one side of the grindstone be lighter, this irregularity can be equalized by affixing pieces of lead, so as to obtain a uniform motion of the stone. It is essential that the stone should be firm on the axis and not move to and fro in the bearings. ”

“ Stones in buildings are not only fixed with mortar, as bricks are, but are further secured in their places by being clamped together with iron clamps. These are short iron bars, from seven to twelve inches long, one and a half wide, and half an inch thick, according to the size of the stone; the ends of the clamps being turned down a little, to afford a better hold. A channel is cut in the two contiguous stones deep enough for the clamp to lie in, and the ends of the channel are sunk deeper, to receive the turned-down ends of the clamp ”

“ When this destruction takes place by simple comparatively rapid superficial solution and removal of the stone, the rate of lowering of the surface amounts sometimes to about a third of an inch (or roughly nine millimetres) in a century, where it is effected by internal displacement, a curvature of two and a half inches with abundant rents, a partial effacement of the inscription and a reduction of the marble to a pulverulent condition may be produced in about forty years, and a total disruption and effacement of the stone within one hundred. ”