Foulard (foolard)

[Fr.] A thin, washable silk (or silk and cotton) dre -stuff, not dyed in the yarn. Foundations. ( Engin. ) The providing of suitable foundations for buildings and other structures is a subject which has called for much consideration of recent years, in view of the weight of the structures now erected and the varying character of the soil on which they are built. This soil may vary from rock to gravel, sand, or quicksand, each of which has its influence on the character of the foundation. A rock bottom needs simply to be levelled off, and its crevices filled with cement or concrete, or arched over where very wide and deep. Soft or disintegrated rock needs removal, and draining is requisite to prevent injury from surface water and springs. If the rock is not continuous, a part of the edifice has to be built on compre ible soil, and some settling usually occurs, though this may be avoided at times by digging deeper until rock is again found. Hard gravel forms an excellent foundation bed, and is capable of sustaining a pre ure of 5,000 Ibs. per sq. foot, or much more than this if rock lies beneath it. In gravel the footings are spread much more than in the case of rock foundations, being usually made 50 per cent wider than the walls they are to sustain.-Sand foundations. Sharp sand, if constantly wet or dry, is practically incompre ible if so confined as to prevent lateral motion. In laying foundations on this material, excavations must go below the frost Ime, and the trenches be thoroughly drained if there is danger of water infiltration. The footings need a 50 per cent. spread, and should be made to fill the whole width of the trench. There is danger that the heavier portions of the structure may force up the sand under the lighter portions, and settle in consequence; and to avoid this danger an equal distribution of the load sbould be provided for by laying a platform or continuous footing of timber or concrete. If the structure be very heavy, it is nece ary to guard against lateral yielding of the sand, especially on sloping sites. For this purpose parallel brick walls, penetrating two or three feet below the bottom, and laid up in cement, are sometimes employed. A le expensive and equally satisfactory method is that of sheet piling. In this, planks are driven close into the soil to the nece ary depth, and spiked at the top to string pieces of timber.Foundations on Quicksand. The most difficult problem in foundation building is in the case of the presence of quicksand, or sand permeated by moving water. Here it becomes nece ary to surround the whole site of the building with sheet piling, and to cover the entire building area with a platform of concrete. In some cases a grillage or platform of logs or squared timbers is first laid in succe ive courses at right angles to each other and bolted together, and the interstices filled with concrete. In either case water must be excluded while the concrete is settling, for fear it may wash it out before it has time to harden. The water is drained into a trench or well, and pumped out until the hardening is complete. The footings and lower walls in this case must be laid in strong hydraulic cement, and protected externally by a coating of asphalt or tar against the percolation of water. The problem is one of the greatest difficulty, subterranean springs having been known to break through a concrete bed two feet in thickne . The best solution of the problem, where available, is to dig down to solid bottom, or to reach it by driving piles. Pile Foundations. These are of two kinds, sand and timber piles. In moist or boggy soils, where not soft enough to cause the sand to work into the earth, sand piling may be employed. Holes 6 feet deep and 6 and 8 inches in diameter are bored in the bottom of the foundation trench and filled with damp sand, well rammed. This distributes the pre ure of the load horizontally as well as vertically, while timber piles distribute it vertically only. It is therefore not nece ary to penetrate to solid bottom, the sand pile having a broad bearing surface. In the case of the timber pile, all the pre ure is transferred to the bottom of the piling, though it has a considerable degree of sustaining strength from the friction of its lateral surface against the soil. Piles need usually to be driven to solid bottom, and are from 20 to 40 feet in length, or even longer. They are driven in rows by the use of a "pile-driver," a heavy iron weight in vertical guides, dropping on the top of the pile. Piles completely buried in sand or water may last for centuries, of which evidence exists in the cities of Venice and Amsterdam, which are largely built upon them. Their chief danger of decay arises from exposure to air; and piles in tidal water should be cut off below the low water mark. Disk piles, with broad flanges at the base, have been used succe fully in India for bridge work; and screw piles, made of metal and driven by turning, have been used effectively in soft strata. Concrete is sometimes used for piling in soft soils with rock at no great depth, holes of considerable width being bored and filled with this material. Isolated piers are thus built up and connected by arches of masonry or metal girders, on which the walls are built.- Platform Foundations. The purpose of the platform is the distribution of the pre ure over an area much wider than that of the walls or footings, and also the prevention of one part of the building settling more than another. The platforms are of concrete, of masonry, of timber, and of iron and concrete. The concrete platform is made by mingling broken or crushed stone or coarse gravel with the proper proportion of hydraulic cement mixed with sand and water, the proportion varying to suit each individual case. The bottom of the excavation, being brought to a level, is covered with the concrete in layers of 9 to 18 inches thick, each layer being thoroughly rammed and allowed to set before the next one is laid. Such platforms are laid under structures of considerable weight and limited area, such as towers, chimneys, and bridge piers, or large buildings having many piers; also in the case of buildings to be erected on wet sands or soils, and where it is nece ary to exclude water from the cellar.-Masonry Platforms. Masonry can be used for platform purposes only by the use of inverted arches. In the case of a heavy building erected on isolated piers instead of continuous walls, a series of inverted arches, turned beneath the feet of the several piers, practically bind them into one, while if barred vaults be built between each line of arches, the loads are distributed over the whole area of the building.- Timber Platforms . What is known as a grillage, composed of squared or round timbers, is often employed. If in a constantly wet soil, or completely buried in sand, such a platform is practically indestructible. The hollows between the timbers may be filled with sand or concrete so as to make a solid ma . After the building of the foundation walls, the platform needs to be completely buried. Timber platforms have been frequently used for foundations both for bridge piers and for tall buildings. The New Orleans custom-house, built upon a very soft and treacherous soil of sandy clay saturated with water, in which piling was not to be trusted, stands upon a timber grillage of logs 12 inches in diameter, laid close together, cro ed by a second layer of logs 3 feet apart. The openings are filled with concrete, and a third layer of 12-inch logs laid above. The building settled about 2 feet during its construction. The great Auditorium Building at Chicago is built upon a ma ive platform of timber, concrete, and steel rails, which is 7 feet in total thickne .-Iron and Concrete Foundations. The method of platform building used in the Auditorium has been employed with succe in many Chicago buildings, the soil there being a wet clay supposed to overlie quicksand, with no solid bottom short of 50 or 60 feet. In the new system a platform of timber or concrete is first formed over an area sufficient to reduce the pre ure to between 3,000 and 4,000 lbs. per sq. foot. On the concrete is laid a layer of steel rails, placed close together, and one or two more upon this, each at right angles to the one below. On top is a layer of 15- or 20-inch I-beams, which sustains the iron or masonry columns or walls. The whole is covered with concrete, and the ends of the beams are protected by a heavy plastering of cement. SUBAQUEOUS FOUNDATIONS. -Foundations for service under water are made by the use of three expedients the coffer-dam, the open crib, and the pneumatic cai on. The coffer -dam is a temporary water-tight wall built around the space to be excavated, and enabling the latter to be kept dry by pumping while the foundations are being made. Two parallel rows of sheet piling are sunk and the space between filled with clay, or mixed clay and sand, thoroughly rammed. Rows of piling are also driven, with string pieces to which the sheet piles are spiked. The open crib or cai on is used in water too deep for the use of the coffer-dam. It is a box-like structure of timber or iron, open, except for a partial flooring or shelf, on which is laid a load sufficient to sink it, while it is made high enough for its top to stand above the water. The bottom of the area is then dredged out, the crib sinking, and new sections being added to it so as to keep its top above the water level. A coffer-dam is thus formed from which the water may be pumped, and the foundations built within it. Or, if it is sunk to a firm bottom, it may be filled with concrete and the piers built upon this material. The pneumatic cai on is the device usually employed in water of considerable depth. In this the principle of the diving bell is used. An air-tight crib or cai on, in the form of an inverted box, with a cutting-edge at the bottom, is floated out to the site of operation, and sunk by weights. The cai on, being filled with air under pre ure, serves as a working chamber for the men, air pumps constantly renewing the air and the water being effectually excluded. Workmen are admitted to or released from the working chamber by the aid of "air locks," or intermediate spaces between an outer chamber filled with air at atmospheric pre ure, and the working chamber filled with compre ed air. These permit entrance and exit without change of pre ure in the working chamber. The workmen enter the air lock by its outer door, which is then closed, and the lower door is opened, admitting the compre ed air until the air of lock and chamber are equal in pre ure, when the workmen may enter the chamber. On leaving, this procedure is reversed. The methods of excavation and foundation building here described are largely of recent origin, though the Romans showed great skill in their building operations, using concrete and hydraulic cement freely in foundations, employing the inverted arch, and using the coffer-dam in subaqueous work. The heavy med iæval structures were usually built in widely-spread footing courses, with a gradual decrease upward in thickne , solid rock or compact gravel being the usual base. In modern times the art of foundation building has been revolutionized by the methods men tioned, and structures of great size and weight can now be erected in soils or in under-water situations where such erections would have been quite impo ible under the methods of the past ages. Fountain, Intermit'tent. (Physics.) The name given to those fountains the flow of which ceases and recommences at regular intervals. Near the lake of Como there is a fountain which, three times a day, increases and diminishes; Pliny the Younger makes mention of it in the 30th Epistle of his 4th Book. In Savoy, on the edge of the Lake of Bourget, exists the Fountain of Wonders , one which flows, stops, and reflows twice in an hour; when the flow is about to begin a bubbling noise is heard, and then the water escapes on three sides, forming jets, the height of which increases at first, and then succe ively diminishes. The water, after springing for seven or eight minutes, stops for the space of two. It would be easy to multiply similar examples. In order to explain such phenomena, let us suppose that a spring is reached by a pipe, or by any natural pa age (o) to a reservoir (M), whence it can escape only by a pa age (a, b, c) forming a siphon. The water accumulates in the reservoir until the level of the water reaches the curvature of the siphon; the fountain then commences to flow by the orifice (c), but if the siphon be allowed to let more water escape at IMG:content-0288.jpg:[graphic][merged small] one time than is received from the spring by the reservoir, the latter becomes exhausted, and the flow ceases until the level of the curvature is again reached. The intermittent fountain used in scientific laboratories is altogether different from the natural objects of the same name; it was invented by Sturmius, and consists of a ve el (A), closed by a gla stopple, and cemented upon a piece of bra provided with three lateral spouts, D D'. The whole is supported by a tube B, which opens into the interior part of the ve el A. This tube is terminated at its other extremity by a basil, and sustained by a tripod. The whole apparatus rests upon a basin, C, percolated by a little hole in its center. The ve el A being filled with water as far as the level of the pipe B, the efflux takes place by the spouts D D'; the falling water becomes accumulated in the basin C, and is replaced by air brought by the tube B; but, if the little orifice bored in the basin be insufficient for its exhaustion, the water by increasing obstructs the inferior part of the pipe B, and, as the air can no IMG:content-0289.jpg:[graphic] Fig. 2899. STURMIUS' INTERMITTENT FOUNTAIN. longer enter in A, the efflux ceases until the extremity of the pipe B is allowed to become disengaged from the water, and the air again permitted to reënter. Fouquet ( foo - kā ' ), NICOLAS, MARQUIS DE BELLE-ISLE, a celebrated French finance minister, born in Paris, 1615, became in 1650 Attorney-General of the Parliament of Paris, and two years afterward superintendent of the finances of the kingdom, in which capacity he di ipated millions of francs on himself and his favorites and pensioners needy literary men, of whom Péli on may be regarded as the type. Falling into disgrace with Louis XIV., on account of his prodigality and sumptuous mode of life, vieing in splendor with that of the court, F. was arrested in 1661 (at an instance, as has been supposed, of his rival Colbert); and, after a trial which lasted three years, was condemned to imprisonment for life. F.'s best trait was his patronage of letters, and constant fidelity to his friends and para sites. Died in 1680. Fourth Estate'. A designation originally applied, in England, to the lowest and unrepresented cla es of society; the "Third Estate" being the commons, which came after nobility and royalty, constituting the second and first, respectively. Now humorously applied, in this country, to the newspaper fraternity, in recognition of its peculiar influence on public affairs.