Delfzyl, which was formerly an important fortress for the protection of the ancient sluices on the little river Delf (hence its name), has greatly benefited by the construction of the Ems (Eems) shipcanal connecting it with Groningen, and has a good harbour with a considerable import trade in wood.
As examples of class (i.) may be mentioned - erection or enlargement of buildings, laying down of permanent pasture, making of gardens or fences, planting of hops, embankments and sluices; as examples of (ii.) - chalking of land, clay burning, application to land of purchased artificial or purchased manure, except they have been made for the purpose of making provision to protect the holding from injury or deterioration.
Under ordinary conditions the sluices are raised to admit boats to pass from the half flood to half ebb, so that the river remains tidal up to Teddington, the next lock.
Long ditches with stone-paved sluices for washing this mineral-bearing material have long been used by the Indians, who also construct stone bars across the beds of the streams to make riffles and hold the deposited grains of gold.
The area south of this would be divided into four polders, with reservation, however, of a lake, Yselmeer, in the centre, whence branches would run to Ysel and the Zwolsche Diep, to Amsterdam, and, by sluices near Wieringen, to the northern part of the sea.
The gain would be the addition to the kingdom of a new and fertile province of the area of North Brabant, a saving of expenses on dikes, diminution of inundations, improvement of communication between the south and the north of the kingdom, protection of isles of the sea, &c. The costs were calculated as follows: (I) enclosing dike, sluices, and regulation of Zwolsche Diep, £1,760,000; (2) reclamation of four polders, £5,200,000; (3) defensive works, £400,000; (4) indemnity to fishermen, £180,000; total, £7,540,000.
Resolved as he said "to die in the last ditch," he rejected all thought of surrender and appealed to the last resource of Dutch patriotism by opening the sluices and laying vast tracts under water.
In workings on a larger scale, where the supply of water is abundant, as in California, sluices were generally employed.
In larger plant the upper ends of the sluices are often cut in rock or lined with stone blocks, the grating stopping the larger stones being known as a " grizzly."
In order to save very fine and especially rusty particles of gold, so-called " under-current sluices " are used; these are shallow wooden tanks, 50 sq.
Sluices are often made double, and they are usually cleaned up - that is, the deposit rich in gold is removed from them - once a week.
The stream, laden with stones and gravel, passes into the sluices, where the gold is recovered in the manner already described.
Now, the dykes were cut and the sluices opened, and Amsterdam was covered by a wide inundation, against which the invader was powerless.
Sluices were arranged to slide be tween the wheel and casing, and by their means the range of action could be varied from 300 H.P. at 120 revs.
1808), who designed the sea-sluices at Katwyk.
The famous dam of Ma'rib and its sluices were the work of this ancient prince - structures which Arnaud in the 19th century found in the same state in which Hamdani saw them a thousand years ago.
By a system of sluices regulating the outflow of the Achray.
It is navigable from Naumburg, too m., with the help of sluices, and is connected with the Elster near Leipzig by a canal.
Long, and over loo bays or sluices, each 161 ft.
There are three distinct classes of weirs, namely, solid weirs, draw-door weirs, including regulating sluices for irrigation, and movable weirs, which retain the water above them for navigation during the low stage of the river, and can be lowered or removed so as to leave the channel quite open in flood-time.
The barrage at the head of the Nile delta, and the regulating sluices across the Nile at Assiut and Esna in Upper Egypt below Assuan, are examples of draw-door weirs, with their numerous openings closed by sluice-gates sliding on free rollers, which control the discharge of water from the river for irrigation.
10, by which date, by damming the lower reaches of the Yser and opening the sluices between Dixmude and Nieuport, a large flooded area was placed between the two armies.
In 1643 it stood a siege of six weeks, but the new governor Ferdinando Fairfax, 2nd Baron Fairfax, obliged the Royalist army to retreat by opening the sluices and placing the surrounding country under water.
Seems to be the first who made it an axiom that strongholds are only to be defended by artillery, the defence before his time having relied mostly on small firearms. He was the inventor of defence by a system of sluices, which proved of the highest importance for the Netherlands.
The Rhine in its course through Holland is merely the parent stream of several important branches, splitting up into Rhine and Waal, Rhine and Ysel, Crooked Rhine and Lek (which takes two-thirds of the waters), and at Utrecht into Old Rhine and Vecht, finally reaching the sea through the sluices at Katwijk as little more than a drainage canal.
Following the example of the great Kampen irrigation canal in Belgium, artificial irrigation is also practised by means of some of the smaller streams, especially in North Brabant, Drente and Overysel, and in the absence of streams, canals and sluices are sometimes specially constructed to perform the same service.
A new feature in diking was the construction of dams or sluices across the mouths of rivers, sometimes with important consequences for the villages situated on the spot.
Owing to the shrinkage of the soil in reclaimed lands, however, that is, lands which have been drained after fen or other reclamation, the sides of the polder are often higher than the middle, and it is necessary by means of small dams or sluices to make separate water-tight compartments (afpolderingen), each having its own unit of measurement.
Nearly all the polders of Zeeland and South Holland are able to discharge naturally into the sea at average low water, self-regulating sluices being used.
As the system of impoldering extended, the small sluggish rivers were gradually cut off by dikes from the marshy lands through which they flowed, and by sluices from the waters with which they communicated.
The chosen line of defence is marked by a series of forts which control the sluices, extending from Amsterdam, through Muiden, thence along the Vecht and through Utrecht to Gorinchem (Gorkum) on the Waal.
The Gedenboek uitgeven ter gelegenheid van het fijftig-jarig bestaan van het Koninklijk Instituut van Ingenieurs, 1847-1897 ('s Gravenhage, 1898), is an excellent aid in studying technically the remarkable works on Dutch rivers, canals, sluices, railways and harbours, and drainage and irrigation works.
In 1901 there were about 5000 negroes employed in the Bahia mines; methods were still primitive; the cascalho was dug out from the river beds or tunnelled out from the valley side, and washed once a week in sluices of running water, where it was turned over with the hoe, and finally washed in wooden basins and picked over by hand; sometimes also the diamantiferous material is scooped out of the bed of the shallow rivers by divers, and by men working under water in caissons.
When a river partakes of the nature of a torrent, dwindling to a paltry stream at one season and swelling into an enormous flood at another, it is impossible to construct a system of irrigation canals without very costly engineering works, sluices, dams, waste-weirs, &c., so as to give the engineer entire control of the water.
Long), at the ends and centre of which is a system of sluices feeding a network of canals.
For this monsoon irrigation there is always abundance of water, and so long as the canals and sluices are kept in repair, there is little trouble in distributing it over the fields.
The distribution of the water over the whole meadow is regulated by the sluices, which should be placed at the origin of every conductor.
By means of these sluices any portion of the meadow that is desired can be watered, whilst the rest remains dry; and alternate watering must be adopted when there is a scarcity of water.
All the sluices should be substantially built at first with stones and mortar, to prevent the leakage of water; for, should water from a leak be permitted to find its way into the meadow, that portion of it will stagnate and produce coarse grasses.
Of course it is necessary to build the mouths of such main drains of very solid masonry, and to construct efficient sluices for the retention of the water in the drains.
Large sluices of stone, with strong doors, to be shut when it is wished to exclude the tide, may be seen on both banks of the river, and from these great conduits are carried miles inward through the flat country to the point previously prepared by embankment over which the muddy waters are allowed to spread.
The water is admitted by valved sluices, which open as the tide flows into the field and shut by the pressure of the confined water when the tide recedes.
These sluices are placed on as low a level as possible to permit the most turbid water at the bottom of the tide to pass through a channel in the base of the embankment.
The expense of forming canals, embankments and sluices for warping land is from Do to £20 an acre.
The adjustment of the water by means of the sluices is a delicate operation when there is little water and also when there is much; in the latter case the fine earth may be washed away from some parts of the meadow; in the former case, by attempting too much with a limited water current, one may permit the languid streams to deposit their valuable suspended matters instead of carrying them forward to enrich the soil.
The ancient system seems simple enough; but in order really to flood the whole Nile Valley during seasons of defective as well as favourable floods, a system of regulating sluices, culverts and syphons is necessary; and for want of such a system it was found, in the feeble flood of 1888, that there was an area of 260,000 acres over which the water never flowed.
Works required for this system are a syphon to pass the high level under the main canal near its head, bridges fitted with sluices where each canal passes under an embankment, and an escape weir at the tail of the system, just south of the desert point, to return surplus water to the river.
There is a lock 80 metres long and 16 metres wide at the left or western end of the weir, and adjoining it are the regulating sluices of the Ibrahimia canal.
Accordingly, when it was determined to construct a dam, it was decided that it should be supplied with sluices large enough to discharge unchecked the whole volume of the river as it comes down until the middle of November, and then to begin the storage.
It is pierced by 140 under-sluices of 150 sq.