Portland stone

“ This cement, which was the first Portland cement in the market, obtained its name from its resemblance when it became stone to the celebrated Portland stone, one of the leading building materials in England. The rocks used in the manufacture of Portland cement are very similar to those from which natural cement is made. The various layers in the natural rock may vary in size or stratification, so that the lime, alumina, and silica may not be in position to combine under heat, or there may be too much of one ingredient, or not enough of the others in close proximity to each other. ”

“ OOLITE PROPER. In the upper oolites, it will be seen, is found the famous Portland stone, in which are some of the most remarkable specimens of the 149extinct fauna of this remote period. “They are found most plentifully in what is locally designated the ‘dirt-bed’ of Portland—a stratum of dark argillaceous mud, which must at one time have been the soil in which they and other vegetables flourished, but which, by a submergence of the land, was converted into the bottom of an estuary, over which other strata of clay, limestone, and sand were deposited. ”

“ The rock, which slopes toward the south-west, is cut into horizontal steps, into which are dovetailed, and united by a strong cement, Portland stone and granite. The whole to the hight of thirty-five feet from the foundation, is a solid body of stones, engrafted into each other, and united by every means of additional strength that could be devised. The building has four rooms, one over the other, and at the top a gallery and lantern. The stone floors are flat above, but concave beneath, and are kept from pressing against the sides of the building by a chain let into the walls. ”

“ The Portland limestones have been much in demand for building purposes; at Portland the “ Top Roach,” the “ Whit Bed ” or top freestone, and the “Best Bed ” (or Base Bed) are the best known. In the Vale of Wardour the lower Portlandian has been largely quarried; the stone from this neighbourhood is often described as Wardour, Tisbury or Chilmark stone. Swindon stone is a calcareous sandstone that occurs in the sands of the Upper Portland beds near Swindon. ”

“ The vaulting of S. Paul’s is a rendering as hard as stone: it is composed of cockle-shell lime well beaten with sand: the more labour in the beating, the better and stronger the mortar. I shall say nothing of marble (though England, Scotland, and Ireland afford good, and of beautiful colours) ; but this will prove too costly for our purpose, unless for Altar-pieces. In windows and doors Portland stone may be used, with good bricks and stone quoins. As to roofs, good oak is certainly the best, because it will bear some negligence. The churchwardens’ care may be defective in speedy mending drips ”

“ Portland stone is frequently employed in the larger buildings, as in St Paul’s Cathedral, and under the various influences of weather and atmosphere acquires strongly contrasting tones of light grey and black. Owing to the by-laws of the County Council, the method of raising commercial or residential buildings to an extreme height is not practised in London; the block known as Queen Anne’s Mansions, Westminster, is an exception, though it cannot be called high in comparison with American high buildings. ”

“ The term is hence applied to every species of unstratified rock, in which detached crystals of felspar are diffused through a base of other mineral composition. Etym., porphyra, purple.
Portland limestone, Portland beds. A series of limestone strata belonging to the upper part of the Oolite group (see Table II'.H, p. 39l.) , found chiefly in England, in the Island of Portland on the coast of Dorsetshire. The great supply of the building stone used in London is from these quarries. ”

“ The alternation of these farms with long tracts of forest, where spruces and pines stand a hundred and fifty feet high, and myriads of wild things have grown in generations of tangle, gives to the country around Portland a charm and flavor peculiarly its own; even into the city itself extends something of the same charm of contrast and antithesis; meandering footpaths, or narrow plank sidewalks with grassy rims, running within stone's-throw of solid brick blocks and business thoroughfares. ”

“ Granite is now the most widely used stone for buildings, monuments, and bridges. Limestone is the second most used building stone. It was widely used before Portland cement became available in the early 19th century because of its uniform color and texture and because it could be easily carved. Sandstone from local sources was commonly used in the Northeastern United States, especially before 1900. Nationwide, marble is used much less often than the other stone types, but it has been used for many buildings and monuments of historical significance. ”

“ All this expansion of an old art has been stimulated by a steady reduction in the price of Portland cement, and by constant improvement in its quality. As the manufacture has expanded, its standards have risen, its machinery has become more economical and trustworthy in results. While the cost of concrete has thus been lowered by a fall in the price of cement, the wages of bricklayers and stone-masons have advanced, adding a new reason for building in concrete, since it requires in execution but little skilled labor. The good points of concrete are manifold ”

“ The stone is really a concrete, formed by mixing very superior Portland cement with crushed Thames gravel, furnace or iron slag, Kentish rag-stone, granite chippings, or other suitable material carefully washed. This fine concrete, after being mixed in the moulds forming the slabs, is thoroughly incorporated by being rocked or jiggled in a trembling machine; this motion, as can be easily understood, making the whole mass even and homogeneous when it sets. The cost of the slabs is about 9d. per square foot, 3 inches in thickness, and they make an excellent footpath. ”

“ If the sand is coarse and the crushed stone or gravel well graded in size of particles, it may be mixed in proportions of 1 part Portland cement, 21⁄2 parts sand, 5 parts gravel or broken stone. All proportions are measured by volume.
Bank run gravel is often used for sidewalk work, particularly where a good bank can be found on the farm. It is safer, if this material be used, to screen out the pebbles, using them as stone, measuring the quantities of stone and sand as described above. Concrete should not be laid in freezing weather. ”

“ The large amount of good hard limestone in the county guarantees an everlasting supply of stone for road making, railroad ballast, crushed rock for concrete works and all other uses to which such limestone may be put. With the Missouri river on the eastern boundary carrying unlimited amounts of sand Atchison county is well supplied with every material needed for unlimited amounts of mortar construction of all kinds. Recently, since Portland cement construction has so effectually replaced stone masonry, this becomes a very important matter. ”

“ The concrete itself should always be the very best quality, and Portland cement should be used on account of its superiority to all others. The aggregate should be the best obtainable and of different sizes, the stones being freshly crushed and screened to pass through a 7/8 in. ring. Very special care should be taken so to proportion the sand as to make a perfectly impervious mixture. The proportions generally used are 4 to 1 and 5 to 1 in the case of gravel concrete, or 1:2:4 or 1:21/2:6 in the case of broken stone concrete. ”

“ All work of this description must be executed in Portland cement, mortar of good strength, to avoid as much as possible the unequal settlement of the deep courses of stone facing and the narrower courses of the brick or rough stone backing. If the backing is of brick it should never be less than 9 in. thick, and whether of stone or brick it should be levelled up in courses of the same thickness as the ashlar. ”

“ The shores are wild and precipitous, and Portland is inaccessible from the sea except towards the south. The highest point, close upon 500 ft., is the Verne hill in the north. Wave action is seen in the numerous caverns, and south-east of Portland Bill, the southern extremity of the isle, is a bank called the Shambles, between which and the land there fiows a dangerous current called the Race of Portland. A raised beach is seen at Portland Bill. The substratum of the island is Kimeridge Clay, above which rests beds of sand and strata of Oolitic limestone, widely famed as a building stone. ”

“ Portland Oolite and Sand (b, Table p. 321) .—The Portland Oolite has already been mentioned as forming in Dorsetshire the foundation on which the fresh-water limestone of the Lower Purbeck reposes (see p. 331) . It supplies the well-known building-stone of which St. Paul’s and so many of the principal edifices of London are constructed. About fifty species of mollusca occur in this formation, among which are some ammonites of large size. The cast of a spiral univalve called by the quarrymen the “Portland screw” (a, Figure 311) , is common; the shell of the same (b) being rarely met with. ”

“ Portland follows the rule of the Pacific Northwest, and builds its residences of wood, which is cheaper, more rapidly built, and more conformable to the climate than brick and stone. The sun is a necessity everywhere along the coast, and a wooden house is quickly warmed through by it, while brick houses exclude the heat, and the winters are seldom cold enough to make thick walls desirable for protection from frost. ”

“ There appears to be no limit to the reproduction in béton of any form used in stone masonry or in stucco. The proportions of material composing the béton for the work varied in strength to meet the requirements of the different parts of the structure: the heavy walls needing the least proportion of cement, while the beams, floors, and roofs required a much larger proportion. Only the best quality of Portland cement, clean beach-sand, and crushed blue-stone, were used in combination with iron for constructing the building. ”

“ First, he must buy Portland cement of the best quality. This cement is made of limestone and clay, or marl, chalk, and slag. These are crushed and ground and put into a kiln which is heated up to 2500° or 3000°F.; that is, from twelve to fourteen times as hot as boiling water. The stone fuses sufficiently to form a sort of clinker. After this has cooled, it is ground so fine that the greater part of it will pass through a sieve having 40,000 meshes to the square inch. To every hundred pounds of this powder, about three pounds of gypsum is added. ”

“ Ott shows that they can make but very feeble resistance to heat. The water enclosed in such rocks accounts for their bursting and exploding when heated. Portland cement-stone is said to show extraordinary resistent power, almost equalling sandstone in this respect. Of brick walls the author is disposed to think well, provided they be honestly built of hard material throughout, and of the requisite degree of thickness. ”

“ Two years after the removal of the Harleian library to the British Museum, Lady Oxford died, leaving an only daughter, Margaret Cavendish, married to William Bentinck, second Duke of Portland. She was the "noble, lovely little Peggy" sung by Prior. As she had inherited none of her father's and grandfather's tastes, it was fitting that the grand collection of MSS., for the sake of which they had impoverished themselves, should enrich an innumerable multitude of scholars and students of all nations and for all time. ”

“ I have very seriously considered the petition to his Grace the Duke of Portland, for the education of my sons, which your friendship for me prompted you to advise me to make, and must acknowledge the particular satisfaction I feel at this further instance of your inclination to serve me with your friendly advice. ”

“ Good results cannot be obtained unless you use a good cement, nor will the work be at its best unless care is taken in the selection of clean sand and clean stone.
Among the uninitiated, there is an all too prevalent idea that anything is good enough for the making of concrete. Some will tell you that sawdust, shavings, mud, clay, etc., will do to complete the mixture, but the absurdity of this notion will very soon become evident to anyone who neglects the precautions which have been above pointed out. ”

“ The New York Code, Section 26, further goes on to say that foundation walls shall be constructed to include all walls and piers built below the curb level or nearest tier of beams to the curb, to serve as supports for the walls, piers, columns, girders, posts or beams. Foundation walls shall be built of stone, brick, Portland cement concrete, iron or steel. If built of rubble stone or Portland cement concrete, they shall be at least 8 in. thicker than the wall above them to a depth of 12 ft. ”

“ Portland merchants are awak- ening to the situation, and Portland will be an equal competitor with Seattle and San Francisco for Oriental trade and gov- ernment business.
SUMPTER. Ore.— W. H. Mead, of Spo- kane, who recently purchased the Glad- stone group of five claims from I. E. Rose, is now developing the property. A tunnel is being driven, and when in 300 feet is ex- pected to tap the ledge. The new company operating the group is the Interstate Mining Company, and the price paid for the five claims was $6000. ”

“ Indeed, it is more easily done than sand, as the water flows through the larger voids in the gravel more readily than through the voids in the sand. Dust may be left in the crushed stone without fear of its interfering with the strength of the cement, but care should be taken to see that such dust is distributed evenly through the whole mass, and when dust is found in stone, slightly less sand should be used than ordinarily. ”