The environs of Creil (Oise) and Chteau-Landon (Seine-et-Marne) are noted for their freestone (pierre de taille), which is also abundant at Euville and Lrouville in Meuse; the production of plaster is particularly important in the environs of Paris, of kaolin of fine quality at Yrieix (1-Jaute-Vienne), of hydraulic lime in Ardche (Le Teil), of lime phosphates in the department of Somme, of marble in the departments of HauteGaronne (St Beat), Hautes-Pyrnes (Campan, Sarrancolin), Isre and Pas-de-Calais, and of cement in Pas-de-Calais (vicinity of Boulogne) and Isre (Grenoble).
A considerable number of men are engaged in the various states on alluvial fields, in hydraulic sluicing, and dredging is now adopted for the winning of gold in river deposits.
The different kinds of motive power used to actuate cranes - manual, steam, hydraulic, electric - give a further classification.
Down to the closing decades of the 19th century hydraulic power was practically the only system available for working cranes from a power station.
There are three Li ting - typical methods: (I) A direct pull may be applied to the hook, either by screws, or by a cylinder fitted with is piston and rod and actuated by direct hydraulic or other pressure, as shown diagrammatically in fig.
This second method forms the basis of the lifting gear in all hydraulic cranes.
Cranes fitted with rotating hydraulic engines may be considered as coming under the third category.
The hydraulic crane has a great advantage in possessing an almost ideal brake, for by simply throttling the exhaust from the lifting cylinder the speed of descent can be regulated within very wide limits and with perfect safety.
An excellent brake for very large cranes is Matthew's hydraulic brake, in which water is passed from end to end of cylinders fitted with reciprocating pistons, cooling jackets being provided.
This drawback can be corrected to a slight extent by furnishing the hydraulic crane with more than one cylinder, and thus compounding it, but the arrangement does not give the same economical range of load "as in an electric crane.
In first cost the hydraulic crane has the advantage, but the power mains are much less expensive and more convenient to arrange in the electric crane.
Where electric or hydraulic cranes are worked from a central station the speed is greater, and may be roughly represented by V =5 +30o/T; e.g.
12 shows an ordinary hydraulic dock-side jib crane.
The subjection of the core to a hydraulic pressure of four tons to the square inch and an electric pressure of 5000 volts from an alternating-current transformer has been adopted, by one manufacturer at least, to secure the detection of masked faults which might develop themselves after submergence.
The pieces are carefully heated with exclusion of air and then compressed into a uniform mass by intense hydraulic pressure; the softened amber being forced through holes in a metal plate.
The chief mineral product is the asphalt of the mines of Seyssel on the eastern frontier, besides which potter's clay, building stone, hydraulic lime and cement are produced in the department.
Sometimes a strip of felt is interposed between the chair and the sleeper, and sometimes a serrated surface is prepared on the sleeper for the chair which is forced into its seat by hydraulic pressure.
The extraordinary architectural skill, the sanitary and hydraulic science revealed in details of the building, bring us at the same time face to face with the power of mechanical invention with which Daedalus was credited.
At the foot of the slope on this side, forming the eastern boundary of the palace, are massive supporting walls and a bastion with descending flights of steps, and a waterchannel devised with extraordinary hydraulic science (Evans, " Palace of Knossos," " Reports of Excavations 1900-1905," in Annual of British School at Athens, vi.
Brick, tile, sewer-pipe, and hydraulic cement are manufactured, and there are railway repair shops.
Before 1405 the mortar used in Venice was made of lime from Istria, which possessed no hydraulic qualities and was consequently very perishable, a fact which to a large extent accounts for the fall of the Campanile of San Marco.
But when Venice took possession of the mainland her builders were able to employ a strong hydraulic dark lime from Albettone, which formed a durable cement, capable of resisting salt water and the corrosive sea air.
Among other important articles of domestic industry are tobacco and cigars (manufactured mainly in bond, within the free harbour precincts), hydraulic machinery, electro-technical machinery, chemical products (including artificial manures), oils, soaps, india-rubber, ivory and celluloid articles and the manufacture of leather.
Long and equipped with electric light, stationary and travelling hydraulic cranes, machinery for meat freezing, and large sheds for storing corn and wool.
The alluvial deposits are almost invariably worked opencast, those of the Malay Peninsula and Archipelago chiefly by Chinese labour: in a few instances hydraulic mining has been resorted to, and in other cases true underground mining is carried on; but the latter is both exceptional and difficult.
This is a suspension bridge with a central portion, between two lofty and massive stone towers, consisting of bascules which can be raised by hydraulic machinery to admit the passage of vessels.
Hydraulic pumping engines, while not differing essentially from steam pumps, must have specially designed valves in the power cylinder on account of the incompressibility of water.
In the Greek school at Alexandria, which flourished under the auspices of the Ptolemies, the first attempts were made at the construction of hydraulic machinery, and about 120 B.C. the fountain of compression, the siphon, and the forcing-pump were invented by Ctesibius and Hero.
Applied by him to the invention of the hydraulic press.
Ih shows also a modern form of the hydraulic press, applied to the operation of covering an electric cable with a lead coating.
With a view of safeguarding themselves from breakdowns caused by the inequality of feeding, or by the action of malicious persons introducing foreign substances, such as crowbars, bolts, &c., among the canes, and so into the mills, many planters have adopted socalled hydraulic attachments, applied either to the megass roll or the top roll bearings.
The toggle-joint attachment, which is an extremely ingenious way of attaining the same end as the hydraulic attachments, is open to the same objections.
Before beetroot had been brought to its present state of perfection, and while the factories for its manipulation were worked with hydraulic presses for squeezing the juice out of the pulp produced in the raperies, the cane sugar planter in the West Indies could easily hold his own, notwithstanding the artificial competition created and maintained by sugar bounties.
But hydraulic presses have now been abandoned, for the juice is universally obtained by diffusion, and the small slicers have gone out of use, because the large amount of pulp they produced in proportion to slices is not suitable for the diffusion process, in which evenly cut slices are required, which present a much greater surface with far less resistance to the diffusion water.
In this form a large number, after being cooked or stoved in moist heat for about twenty-four hours, are piled between plates in an hydraulic press, and subjected to great pressure for a month or six weeks, during which time a slow fermentation takes place, and a considerable exudation of juice results from the severe pressure.
In an hydraulic press, by which they are moulded into Tobacco solid cakes.
When hydraulic pressure to the amount of 2000 to 3000 lb per square inch is applied, the saving is unquestioned, since less time is required to dry the pressed retort, its life in the furnaces is longer, its absorption of zinc is less, and the loss of zinc by passage through its walls in the form of vapour is reduced.
Modern methods of hydraulic mining have been introduced to work the auriferous banks of Poto; elsewhere antiquated methods only are employed.
A hydraulic canal provides the city with good water power, and in 1905, in the value of its factory products ($13,992,574, being 31.3% more than in 1900), Hamilton ranked tenth among the cities of the state.
In addition to the Adige embankment, other hydraulic works have been either completed or undertaken.
The Mad river is made to furnish good water-power by means of a hydraulic canal which takes its water through the city, and Dayton's manufactures are extensive and varied, the establishments of the National Cash Register Company employing in 1907 about 4000 wage-earners.
This decrease was largely caused by the practical suspension for many years of the hydraulic mining operations, in preparation for which millions of dollars had been expended in deep tunnels, flumes, &c., and the active continuance of which might have been expected to yield some £2,000,000 of gold annually.
This interruption, due to the practical prohibition of the industry by the United States courts, on the ground that it was injuring, through the deposit of tailings, agricultural lands and navigable streams, was lessened, though not entirely removed, by compromises and regulations which permit, under certain restrictions, the renewed exploitation of the ancient river-beds by the hydraulic method.
- This method is employed to extract gold from both alluvial and reef deposits: in the first case it is combined with " hydraulic mining," i.e.
Gold dredging is treated by Captain C. C. Longridge in Gold Dredging, and hydraulic mining is discussed by the same author in his Hydraulic Mining.
All attempts to dispense with a lead and line and to measure the depth by determining the pressure at the bottom have hitherto failed when applied to depths greater than 200 fathoms; a new hydraulic manometer has been tried on board the German surveying ship " Planet."
It consists of a small hydraulic press, which forces a set of expanding bits or wedges into a bore-hole previously bored by a long screw augur or drill, worked by hand, the action of the press being continued until a sufficient strain is obtained to bring down the coal.
The arrangement is, in fact, a modification of the plug and feather system used in stone quarrying for obtaining large blocks, but with the substitution of the powerful rending force of the hydraulic press for handpower in driving up the wedges.
An arrangement of this kind for shifting the load from a large cage at one operation was introduced by Fowler at Hucknall, in Leicestershire, where the trains are received into a framework with a number of platforms corresponding to those of the cage, carried on the head of a plunger movable by hydraulic pressure in a vertical cylinder.
With Fowler's hydraulic arrangement 2000 tons are raised 600 yds.