Drainage Sentence Examples
The drainage of marshes and marshy lands has considerably extended.
The drainage of Manitoba is entirely northeastward to Hudson Bay.
Below the confluence the Kabul becomes a rapid stream with a great volume of water and gradually absorbs the whole drainage of the Hindu Kush.
These basins of internal drainage are calculated to amount to 22% of the land surface.
The suggested causes are (I) reduction of insects by drainage, (2) reduced population, (3) the use of quinine.Advertisement
Excellent examples of the indecisive drainage of a new land surface, on which the river system has not had time to impress itself, are to be seen in northern Canada and in Finland, where rivers are separated by scarcely perceptible divides, and the numerous lakes frequently belong to more than one river system.
On the south bank, owing to better natural drainage and a drier subsoil, movement was fairly easy, but the Austrians found it almost impossible.
The general slope of the plateau is toward the N., and the drainage of the state is chiefly through the above-named rivers - the principal tributaries of the Araguaya being the Grande and Vermelho, and of the Upper Tocantins, the Manoel Alves Grande, Somno, Paranan and Maranhao.
The drainage system here, including a water-closet, is of the most complete and modern kind.
South of the divide the level at once drops to the central depression of Gobi, which forms a vast interior, almost waterless space, where the local drainage is lost in deserts or swamps.Advertisement
The greater part of western Asia, including the basin of the Obi, the drainage area of the Aral Sea, together with Afghanistan, Baluchistan, Persia and Arabia, was covered by the sea during the later stages of the Cretaceous period; but a considerable part 3f this region was probably dry land in Jurassic times.
Various works of a more or less imperfect character were carried out, such as the bridging over in 1637 of the Drainage.
The Bebedero, in San Luis, and Porongos, in Cordoba, and others, are shallow, saline lakes which receive the drainage of a considerable area and have no outlet.
Among its many small tributaries are the Catuche, Caroata and Anauco, which flow down through the city from the north and give it a natural surface drainage.
The unhealthiness of the city is chiefly due to want of proper drainage, impure drinkingwater, miasma from the disturbed rubbish heaps, and contaminated dust from the uncleansed roads and streets.Advertisement
Thus, for example, in a mountain range at right angles to a prevailing sea-wind, it is the land forms which determine that one side of the range shall be richly watered and deeply dissected by a complete system of valleys, while the other side is dry, indefinite in its valley systems, and sends none of its scanty drainage to the sea.
It is fortunate that the city is not close-built or crowded, for since the first advent of foreigners in Peking in 1860 nothing whatever had been done until 1900 to improve the streets or the drainage.
On the western frontier a northern extension of the great central chain of Goyaz forms the water-parting between the drainage basins of the Sao Francisco and Tocantins, and is known at different points as the Serra do Paranan, Serra de Sao Domingos and Serra das Divisoes.
The central and greater part of the state, however, is included in the drainage basin of the upper Sao Francisco.
The natural process of sedimentation assisted the gradual artificial drainage of the marshes by means of embankments confining the river.Advertisement
The carbon compounds of the latter are of no direct nutritive value to the succeeding crop, but the decaying vegetable tissues very greatly assist in retaining moisture in light sandy soils, and in clay soils also have a beneficial effect in rendering them more open and allowing of better drainage of superfluous water and good circulation of fresh air within them.
The drainage of New York finds its way to the sea in various directions.
Fine stone palaces, richly decorated, with separate sleeping apartments, large halls, ingenious devices for admitting light and air, sanitary conveniences and marvellously modern arrangements for supply of water and for drainage, attest this fact.
In the case of proposed drainage improvements, notice in writing must be given to the landlord, who may then execute the improvements himself and charge the tenant with interest not exceeding 5% per annum on the outlay, or such annual instalments, payable for a period of twenty-five years, and recoverable as rent, as will repay the outlay, with interest at the rate of 3% a year.
In the moist bottom-lands along the rivers it is the custom to throw the soil up in high beds with the plough, and then to cultivate them deep. This is the more common method of drainage, but it is expensive, as it has to be renewed every few years.Advertisement
Shut off from the adjacent Indian Ocean by its mountain barrier, the drainage of the country is westward to the distant Atlantic. As its name implies, the chief rivers rise in Mont aux Sources.
A peculiar feature of the drainage of the state is the large number of subterranean streams and of springs, always found to a greater or less extent in limestone regions.
Florida, the richest class, which require drainage to fit them for cultivation.
It contains all the best land in Berar; it is full of deep, rich, black alluvial soil, of almost inexhaustible fertility, and it undulates sufficiently to maintain a natural system of drainage, but there is nothing picturesque about this broad strip of champaign country.
The city secured in 1906 a new and adequate water-supply, modern drainage works having been completed the previous year.
The tidal action of the gulf is so slight and the marshes are so low that perfect drainage cannot be obtained through tide gates, which must therefore be supplemented by pumping machinery when rains are heavy or landward winds long prevail.
There are many " bayous," several of which are of great importance, both for navigation and for drainage.
These prairies are traversed by ridges, which facilitate irrigation, and are underlaid by an impervious subsoil, which facilitates both effective storage and drainage.
The danger of floods and the difficulty of drainage make the extension of the practice unprofitable, and the opening of the prairies has made it unnecessary.
Many bayous are convertible by improvement into excellent drainage and irrigation canals.
Spain set up no claim to the region, and when Robert Cavalier, Sieur de la Salle, came down the river in 1682 from the French possessions to the north, he took possession in the name of France, which hereby gained her first title to the vast drainage basin of the Mississippi.
These pouch harbours are probably " drowned " drainage basins.
The drainage of the interior of Greenland is thus partly given off in the solid form of icebergs, partly by the melting of the snow and ice on the surface of the ice-cap, especially near its western margin, and to some slight extent also by the melting produced on its under side by the interior heat of the earth.
It was a lake until modern times, when it was included in a scheme of drainage.
This lake drained southward into the Gulf of Mexico via the Minnesota and Mississippi rivers, until the ice sheet which had prevented its natural drainage to the north had melted sufficiently to allow it to be drained off into Hudson Bay by way of the Nelson River.
These trenches have for successive geological periods been the drainage valleys of immense lakes (probably also of glaciers) which formerly extended over the plateau or fiords of the seas which surrounded it.
The White Horse Hills and the Chilterns strike right across the Thames basin, but almost their entire drainage from either flank lies within it, and similarly a great part of the low-lying Weald, though marked off from the rest of the basin by the North Downs, drains into it through these hills.
In this part of its course the river receives from the south the streams, often intermittent, which rise on the northern slopes of the Stormberg, Zuurberg and Sneeuwberg ranges - the mountain chain which forms the water-parting between the coast and inland drainage systems of South Africa.
Another important river is the Hlaing, which runs through the district from north to south, receiving from the east, through numerous channels, the drainage of the Pegu Yoma Mountains, which fertilizes the plain on its eastern bank.
If the Tocantins-Araguaya basin is included in the hydrographic system, the greater part of Goyaz and a small part of Maranhao should be added to this drainage area.
Piauhy is wholly within its drainage basin, although the river forms the boundary line between that state and Maranhao throughout its entire length.
Those of the Paraguay drain the south-western part of Matto Grosso, and the tributaries of the Parana cover the western slopes of the Serra do Mar from Rio Grande do Sul north to the south-west part of Minas Geraes, and include the south-east part of Matto Grosso and the south part of Goyaz within their drainage basin.
The Berettyo canal between the Koros and the Berettyo rivers, and the Kdrds canal along the White Kiirds were constructed in conjunction with the regulation of the Theiss, and for the drainage of the marshy region.
It receives the drainage of the northern slopes of the Satpuras, but not that of the Vindhyan tableland, the streams from which flow into the Ganges and Jumna.
The rest of the country is divided between the drainage areas of the Vaal and Limpopo.
All this region belongs to the drainage basin of the Orinoco, and rivers of large volume flow down between these spurs.
Drainage restored trade before 1634, and the act of 1773 for making Kinderley's Cut was the beginning of prosperity.
The area of the drainage basin is estimated at 56,000 sq.
A study of the changes going on in the rif tvalley in which the lakes lie leads, however, to the belief that the Albert Edward and Albert Nyanzas are drying up, a process which the nature of the drainage areas is helping to bring about.
Albert Nyanza, on the other hand, is threatened in the distant future with destruction from another cause - the filling of its bed by the alluvium poured into it by the Semliki, the Victoria Nile and, in a lesser degree, by other streams. The Semliki receives directly or indirectly the whole of the drainage of Ruwenzori, and also that of the eastern face of the Congo mountains as well as the drainage basin of Albert Edward Nyanza.
The combined drainage area, including the water surface of Albert Edward Nyanza, the Semliki and Albert Nyanza, is some 16,600 sq.
A system of main drainage was inaugurated by the Commissioners of Sewers in 1849, but their work proceeded very slowly.
The sanitary authorities are concerned only with the supervision of house drainage, and the construction and maintenance of local sewers discharging into the main system.
The Metropolitan Board of Works was also given certain powers of supervision over the vestries and district boards, and superseded the commissioners of sewers as authority for main drainage.
The vestries and district boards became the authorities for local drainage, paving, lighting, repairing and maintaining streets, and for the removal of nuisances, &c.
The latter includes not only the actual excavation of the mineral, but also haulage and hoisting by which it is brought to the surface, timbering and other means of supporting the excavations, and the drainage and ventilation of mines.
Either may be used for drainage of the mine workings, in which case it becomes an adit.
As already noted large pillars must always be left to protect shafts, adits and the more important mine-passages necessary for drainage, ventilation and the haulage of mineral.
In many mining regions long tunnels have been driven at great expense to secure natural drainage.
Under modern mining conditions drainage tunnels have lost much of their former importance.
Drainage channels are provided, usually along the main haulage roads, by which the water flows to a sump excavated at the pump shaft.
In driving mine passages thatj are to be used for drainage, care is taken to maintain sufficient gradient.
As the larger part of the water in a mine comes from the surface, the cost of drainage may be reduced by intercepting this surface water, and collecting it at convenient points in the pump shaft from which it may be raised at less cost than if permitted to go to the bottom.
As he is called upon to construct lines of transport, both underground and on the surface, works for water-supply and drainage, and buildings for the handling, storage and treatment of ore, he must be trained to some extent as a civil engineer.
The Hindu Kush is, in fact, but the face of a great upheaved mass of plateau-land lying beyond it northwards, just as the Himalaya forms the southern face of the great central tableland of Tibet, and its general physiography, exhibiting long, narrow, lateral valleys and transverse lines of "antecedent" drainage, is XIII.
It marks the commencement of the water-divide which primarily separates the Gilgit basin from that of the Yashkun, or Chitral, river, and subsequently divides the drainage of Swat and Bajour from that of the Chitral (or Kunar).
The Bahr-el-Ghazal itself is described as a drainage channel rather than a true river.
Its length is 300 m., and the area of its drainage basin extends to 22,800 sq.
The drainage system is still somewhat imperfect, but the water brought from the hills or from the Arno in pipes is fairly good, and the general sanitary conditions are satisfactory.
If it allows of too free drainage drought sets in and the plants, not getting enough water for their needs, become stunted in size.
It is the business of the farmer and gardener to promote the activity of these organisms by good tillage, careful drainage and occasional application of lime to soils which are deficient in this substance.
They are, however, very readily absorbed by growing plants, so that in summer, when nitrification is most active, the nitrates produced are usually made use of by crops before loss by drainage takes place.
In the majority of cases the good results obtained are more particularly due to the setting free of " dormant " or " latent " food constituents and to the amelioration of the texture of the soil, so that its aeration, drainage, temperature and water-holding capacity are altered for the better.
Gripping and draining ploughs are employed in opening the grips and trenches necessary both in surface and underground drainage.
He was unable, however, to proceed farther east than his predecessors, and the problem of the Jauf drainage and its possible connexion with the upper part of the Hadramut valley still remains unsolved.
The Itata river, which forms the southern boundary, and its principal tributary, the Nubee, form the drainage system of the province.
Another sanitary work of great importance was the improvement carried out in the drainage system, and the regulation of the river Wien.
Its length is 247 m., and its drainage area 479 0 sq.
The grand duke Cosmo I., a genuine statesman, not only restored the university, but instituted the "uffizio dei fossi," or drainage office for the reclamation of marsh lands, and founded the knighthood of St Stephen.
The Xauxa, becoming afterwards the Mantaro, received the drainage of Xauxa, Huancavelica and Ayacucho.
It is roughly mountainous, and belongs to the closed drainage basin of western Argentina, centring in the province of Mendoza.
Since the beginning of the 10th century strenuous efforts have been made to improve the sanitary condition by a new system of drainage, a better water service, the filling up of marshes wherein the malarial mosquito breeds, and in other directions.
The rivers are small and flow chiefly to the San Juan, a part of the Panuco drainage basin.
In 1892 work was begun on the Chicago Drainage Canal, whose controlling works are here and whose plant, developing 40,000 h.p. from the 40 ft.
For the drainage and sewerage of the city a subterranean river whose source and mouth are unknown is utilized.
This species swarms in some years in prodigious numbers; in Pennant's time amazing shoals appeared in the fens of Lincolnshire every seven or eight years, No instance of a similar increase of this fish has been observed in our time, and this possibly may be due to the diminished number of suitable breeding-places in consequence of the introduction of artificial drainage.
The city is provided with tramways, telephone service and electric lighting, but the water supply and drainage are inferior.
There is a modern system of drainage for the towns, and all sewerage has been intercepted from the Grand Harbour.
Tenders were strictly enforced in letting government property and contracts; a largely increased revenue was applied on water supply, drainage and other works.
The city is also one of the filthiest in the East, as there are no means of drainage or sewerage, and garbage of every description lies in heaps in the open streets.
Through this stretch of dasht the drainage from the main water-divide breaks downwards to the plains of Herat, where it is arrested and utilized for irrigation purposes.
The city is built in a bowllike depression of the great central plateau, and the drainage from the surrounding hillsides has produced a dangerously insanitary condition, from which one or two virulent fever epidemics have resulted.
The cause of this change is not known, but it is attributed to extensive drainage and removal of vegetation in the immediate neighbourhood of the town.
The drainage of the station is all modern, and the sewage is disposed of on a sewage farm under the direction of the war department.
Cape Town is provided with an excellent water supply and an efficient drainage system.
To the west of this ridge the water collects to form the Asan, a tributary of the Jumna; whilst to the east the Suswa receives the drainage and flows into the Ganges.
To the east the valley is characterized by swamps and forests, but to the west the natural depressions freely carry off the surface drainage.
The Valley, including the drainage basin of Lake Zumpango, has an area of 1219 sq.
Mexico was formerly one of the worst drained large cities of the New World, its subsoil being permanently saturated and its artificial drainage being through open ditches into the San Lazaro Canal which nominally discharged into Lake Texcoco.
In 1856 President Ignacio Comonfort invited tenders for drainage works conditional on the use of waste waters for irrigation purposes, and the plan executed consists of a canal and tunnel 43 m.
Muskhogean tribes were potters, but Siouan tribes, as a rule, in all the Mississippi drainage were not.
The Algonquin-Iroquois took up the journey at Bear Lake and its tributaries, and by means of paddling and portages traversed the area of middle and eastern Canada, including the entire St Lawrence drainage.
Algonquin-Iroquois Canada, thanks to the Geological Survey and the Department of Education in Ontario, has revealed old Indian camps, mounds and earthworks along the northern drainage of Lakes Erie and Ontario, and pottery in a curved line from Montreal to Lake of the Woods.
The fifth labour seems to symbolize some great improvement in the drainage of Elis.
It broadened and deepened many of the valleys; rounded the hills; turned aside many streams, causing changes in drainage and giving rise to innumerable waterfalls and rapids; and it formed the thousands of lakes, large and small, which dot the surface.
Thus New York is pre-eminently a divide region, sending its drainage, by various courses, into widely separated parts of the ocean.
The Hudson (q.v.) is essentially a New York stream, though it receives some drainage from the New England States through its small eastern tributaries.
The action of the continental glacier in scouring down the passes between the St Lawrence and southern drainage, and in turning streams southward, has facilitated the building of railways across the divides.
The drainage of the Vosges valleys and of the Rhine valley is collected and carried into the Rhine about 10 m.
The whole country forms part of the drainage basin of the Orange river, its streams, with insignificant exceptions, being tributaries of the Vaal or Caledon affluents of that river.
The main range of the Rocky Mountains separates that part which is drained west into the'Columbia river and the Pacific Ocean from that which is drained east into the Missouri and Mississippi rivers and the Gulf of Mexico, and from a very small part which is drained north-east into Hudson Bay; the water-parting which in Montana separates the drainage into Hudson Bay from the drainage into the Gulf of Mexico crosses only the north-west region of Teton county.
A " culvert " is a bridge of small span giving passage to drainage.
With the exception of the extreme north-east, the state lies within the drainage system of the Missouri river.
There are throughout the state occasional tracts in which, owing to deficient drainage, an excess of alkali '507 has accumulated, and which require special treatment before they can be made again productive.
It occupies an area of 44 square miles and has a drainage basin of 372 square miles.
To the south of Hythe this shore borders the wide expanse of Romney Marsh, which, immediately west of Hythe, is overlooked by a line of abrupt hills, but for the rest is divided on the north from the drainage system of the Stour only by a slight uplift.
The main watershed follows a tortuous course which crosses the mountainous belt just north of New river in Virginia; south of this the rivers head in the Blue Ridge, cross the higher Unakas, receive important tributaries from the Great Valley, and traversing the Cumberland Plateau in spreading gorges, escape by way of the Cumberland and Tennessee rivers to the Ohio and Mississippi, and thus to the Gulf of Mexico; in the central section the rivers, rising in or beyond the Valley Ridges, flow through great gorges (water gaps) to the Great Valley, and by southeasterly courses across the Blue Ridge to tidal estuaries penetrating the coastal plain; in the northern section the water-parting lies on the inland side of the mountainous belt, the main lines of drainage running from north to south.
The master streams of the present have inherited their channels from the drainage systems of the Cretaceous lowland, and though raised athwart the courses of the lowland trunk streams the great arch was developed so slowly that these channels could be maintained through pari passu deepening.
The drift plains also contain numerous shallow hollows, locally termed " pots and kettles," which receive the drainage of their vicinity and form sloughs.
Irrigation is confined to the western half of the state, and more especially to the north-west, being employed chiefly in the drainage basin of the Missouri river.
In the western parts of the system they mostly go to feed the Kara-muren or the Cherchen-darya, while farther east they flow down into some larger self-contained basin of internal drainage, such as the Achik-kol, the two lakes Kara-kol, or the Ghaz-kol, and even yet farther east make their way, some of them into the lakes of the Tsaidam depression or become lost in its sands or in those of the Kum-tagh desert on the north, or go to feed the headstreams of the great rivers, the Hwang-ho (Yellow River) and the Yangtsze-kiang (Blue River) in the south.
To secure perfect drainage and greater warmth a fair quantity of sand or grit should be present.
From the point of view of public convenience, too large a space is fatiguing and makes it more difficult to see the animals, whilst the expenses of maintenance, drainage and supervision increase out of proportion to the advantages.
There must be an abundant supply of fresh air and of water, and a drainage system as complete as possible.
A water-parting extending from north-east to south-west and close to the Atlantic border separates the East Shore into two drainage systems, though that next to the Atlantic is insignificant.
The drainage of the region under which the caverns lie is mostly underground.
They may be divided into two classes; those of the plateau region which occupy lacustrine depressions and receive the drainage of the surrounding country; and the tide-water lagoons of the coast formed by the building up of new sand beaches across the indentations in the coast-line.
They receive considerable surface drainage, but are slowly diminishing in area.
Its surroundings are bleak and sterile and its waters brackish and polluted with the drainage of the neighbouring city for nearly four centuries.
Texcoco is now connected with the new drainage works of the capital and is no longer a menace to its population through inundations and pestilential fevers.
The size of this isolated drainage basin is very large, the Nazas River alone having a length of about 370 m.
The problem for the agriculturist here is not irrigation, but drainage and keeping down spontaneous growths.
The great drainage scheme which completed the works of the 17th century by taking out the surplus waters of the southern lakes of the valley of Mexico was devised in 1856, begun under Maximilian, proceeded with intermittently till 1885, then taken up with improved plans, practically completed by 1896, and inaugurated in 1900; 2 the harbour of Vera Cruz was finished in 1902; the Tehuantepec railway, likely to prove a formidable rival to any interoceanic canal, was opened on the 24th of January 1906.
The lacustrine system of the St Lawrence flows eastward from a relatively narrow drainage area.
The south-east course of the middle-section rivers is the result of many changes from the initial drainage; the Mesozoic and Tertiary upwarprngs were probably very influential in determining the present general courses.
The drainage of New England is unlike that of the middle and south-western Appalachians in the occurrence of numerous lakes and falls.
In New England also a wellestablished drainage undoubtedly prevailed in preglacial times; but partly in consequence of the irregular scouring of the rock floor, and even more because of the very irregular deposition of unstratified and stratified drift in the valleys, the drainage is now in great disorder.
It is a peculiar feature of the drainage in North Carolina that the headwaters lie to the east of the highest mountains, and that the chief rivers flow north-westward through the mountains to the broad valley lowland of the stratified belt and then through the plateau, as the members of the Mississippi system.
The coastal lowland between the sea arms is so flat that, although distinctly above sea-level, vegetation hinders drainage and extensive swamps or pocossins occur.
When the ice of the last glacial epoch had retreated so far that Its front lay on a northward slope, belonging to the drainage area of the Great Lakes, bodies of water accumulated in front of the ice margin, forming glacio-marginal lakes.
The drift deposits thereabouts are so heavy that the present divides between the drainage basins of Hudson Bay, Lake Superior and the Gulf of Mexico evidently stand in no very definite relation to the preglacial divides.
The northern part of the peninsula is composed largely of a weak limestone; here much of the lowland drainage is underground, forming many sink-holes (swallOwholes).
The h L lower Mississippi receives no large tributary from the T e ower east, but two important ones come from the west; the Mississippi Arkansas drainage area being a little less than that River.
This valley in the coastal plain, with the much narrower rock-walled valley of the upper river in the prairie states, is the true valley of the S3ississippi river; but in popular phrase the Mississippi valley is taken to include a large central part of the Mississippi drainage basin.
The floods of the Mississippi usually occur in spring or aummer; Owing to the great size of the drainage basin, it seldom happens that the three upper tributaries are in flood at the same time; the coincident occurrence of floods in only two tributaries is of serious import in the lower river, which rises 30, 40, or occasionally 50 ft.
Its total length is about 2000 m., and its drainage basin (greater than that of the Upper Mississippi) about 185,000 sq.
The cyst should be treated like a liver-abscess, by incision through the abdominal or thoracic wall, by circumferential suturing and by exploration and drainage.
The slope of the land is from north-west to south-east, but the general drainage is very inadequate.
The larch of Europe is essentially a mountain tree, and requires not only free air above, but a certain moderate amount of moisture in the soil beneath, with, at the same time, perfect drainage, to bring the timber to perfection.
Another improvement was the completion and embellishment of the Mangue canal, originally designed as an entrance to a central market for the boats plying on the bay, but now destined for drainage purposes and as a public pleasure ground.
The high land and temperate climate, and the excellent drainage and water-supply systems, make Buffalo one of the most healthy cities in the United States, its death-rate in 1900 being 14.8 per thousand, and in 1907 15.58.
The zone between Burma and Siam, established by an agreement between Great Britain and France dated the 15th of January 1896, declared " the portion of Siam which is comprised within the drainage basin of the Menam, and of the coast streams of a corresponding longitude," neutral as between them.
With the exception of the Kunhar river, which flows down the Kagan valley to the Jhelum, the whole drainage of the province eventually finds its way into the Indus.
Three miles below Lakki it is joined by the Tochi or Gambela, which carries the drainage of North Waziristan.
The greater part of the drainage is discharged into the Chambal, which forms the north-western and northern and eastern boundary.
All this drainage, collected into two rivers, the Belikh and the Khabur, is towards the left bank of the Euphrates, for the Mesopotamian watershed seems to be only some 15 m.
The length of the river is nearly 3000 m., and the area of its drainage basin 970,000 sq.
The present course of the Upper Allegheny river is the result of the glacier which blocked the northward drainage of the region through which it flows and turned it southward.
Provision for drainage was made by a channel running round the enclosure.
The drainage of the Altis followed two main lines.
Formerly it was common in Britain, but extensive drainage and persecution Bittern.
Its waters are mainly collected from the rainfall upon the plateaux, and from the hot springs and geysers, most of which are within its drainage area.
The efficiency of drainage, digging, hoeing and like operations is accounted for by the manner in which they promote aeration of the soil, raise its temperature and remove its stagnant water.
When the subsoil is too compact to be pervious to water, effectual drainage must be resorted to; when it is very loose, so that it drains away the fertile ingredients of the soil as well as those which are artificially supplied, the compactness of the stratum should be increased by the addition of clay, marl or loam.
The same end, that of keeping the finer particles of the soil from mixing with the drainage crocks, may be attained by shaking in a little clean moss.
The soil for these may be somewhat coarser, and the amount of drainage material more ample.
For epiphytal plants like orchids the most thorough drainage must be secured by the abundant use of potsherds, small pots being sometimes inserted inside the larger ones, or by planting in shallow pots or pans, so that there shall be no large mass of soil to get consolidated.
When repotting is adopted as a temporary expedient, as in the case of bedding-out plants which it is required to push forward as much as possible, it will suffice if provision is made to prevent the drainage hole from getting blocked, and a rich light compost is provided for the encouragement of the roots.
For potting or basketing purposes, or for plants requiring blockculture, the materials used are light fibrous peat, special leaf-mould, osmunda or polypodium fibre and living sphagnum moss, which supply free drainage for the copious supply of water required.
It must be further remarked that both the " dunepans," or depressions, which are naturally marshy through their defective drainage, and the geest grounds - that is, the grounds along the foot of the downs - have been in various places either planted with wood or turned into arable and pasture land; while the numerous springs at the base of the dunes are of the utmost value to the great cities situated on the marshy soil inland, the example set by Amsterdam in 1853 in supplying itself with this water having been readily followed by Leiden, the Hague, Flushing, &c.
The entire drainage of Holland is into the North Sea.
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.
The circumstance that so much of Holland is below the sea-level necessarily exercises a very important influence on the drainage, the climate and the sanitary conditions of the country, as well as on its defence by means of inundation.
Impoldering for its own sake or on a large scale was impossible as long as the means of drainage were restricted.
It became usual, therefore, to make the subsequent drainage of the land a condition of the extraction of peat from it, this condition being established by proclamation in 1595.
The drainage of the country is effected by natural or artificial means, according to the slope of the ground.
As a matter of course the smaller streams have been largely utilized in their formation, while the necessity for a comprehensive drainage system has also contributed in no small degree.
After 1849 the canal programme was again taken up by the state, which alone or in conjunction with the provincial authorities constructed the Apeldoorn-Dieren canal (1859-1869), the drainage canals of the " Peel " marsh in North Brabant, and of the eastern provinces, namely, the Deurne canal (1876-1892) from the Maas to Helenaveen, the Almelo (1851-1858) and Overysel (1884-1888) canals from Zwolle, Deventer and Almelo to Koevorden, and the Stieltjes (1880-1884), and Orange (1853-1858 and 1881-1889) canals in Drente, the North Williams canal (1856-1862) between Assen and Groningen, the Ems (1866-1876) ship canal from Groningen to Delfzyl, and the New Merwede, and enlarged the canal from Harlingen by way of Leeuwarden to the Lauwars Zee.
In 1876 an agreement was arrived at with Germany for connecting the important drainage canals in Overysel, Drente and Groningen with the Ems canal system, as a result of which the Almelo-Noordhorn (1884-1888) and other canals came into existence.
Again, a totally different character belongs to the canals in North Brabant, and the east and north-east of Holland where, in the absence of great rivers, they form the only waterways which render possible the drainage of the fens and the export of peat; and unite the lesser streams with each other.
Thus in Overysel, in addition to the canals already mentioned, the Dedemsvaart connects the Vecht with the Zwarte Water near Hasselt; in Drente the Smildervaart and Drentsche Hoofdvaart unites Assen with Meppel, and receives on the eastern side the drainage canals of the Drente fens, namely, the Orange canal and the Hoogeveen Vaart (1850-1860; 1880-1893).
The district sloping down from Velletri to the dead level of the Pontine (Pomptine) Marshes has not, like the western and northern slopes of the Alban Hills, drainage towards the Tiber.
In ancient, and probably pre-Roman, times this district was drained by an elaborate system of cuniculi, small drainage tunnels, about 5 ft.
When they fell into desuetude, malaria gained the upper hand, the lack of drainage providing breeding-places for the malarial mosquito.
Remains of similar drainage channels exist in many parts of the Campagna Romana and of southern Etruria at points where the natural drainage was not sufficient, and especially in cultivated or inhabited hills (though it was not necessary here, as in the neighbourhood of Velletri, to create a drainage system, as streams and rivers were already present as natural collectors) and streams very frequently pass through them at the present day.
The drainage channels which were dug for the various crater lakes in the neighbourhood of Rome are also interesting in this regard.
As the drainage by cuniculi removed the moisture in the subsoil, so the drainage of the lakes by emissaria, outlet channels at a low level, prevented the permeable strata below the tufa from becoming impregnated with moisture which they would otherwise have derived from the lakes of the Alban Hills.
What had previously, it seems, been a well-peopled region, with peasant proprietors, kept healthy by careful drainage, became in the 4th and 3rd centuries B.C. a district consisting in large measure of huge estates (latifundia) owned by the Roman aristocracy, cultivated by gangs tion, of slaves.
The methods employed have been three - (i.) the cutting of drainage channels and clearing the marshes by pumping, the method principally employed; (ii.) the system of warping, i.e.
The latter part of the palace is composed of a number of private rooms and halls, and is especially remarkable for its skilful drainage and water-supply systems.
A little east of the Gulf of Enzeli, which resembles the Kara-boghaz, though on a much smaller scale, the Sefid-rud pours into the Caspian the drainage of the western end of the Elburz range, and several smaller streams bring down the precipitation that falls on the northern face of the same range farther to the east.
The surface of this table-land slopes from west to east, as indicated by the direction of the drainage of the country, - the great rivers, the Cauvery, Godavari, Kistna and Pennar, though deriving their sources from the base of the Western Ghats, all finding their way into the Bay of Bengal through fissures in the Eastern Ghats.
When opened up by an elaborate and complete system of drainage, they have been found to possess the power of producing enormously heavy yields, and it is from such estates that the greatest yields in India have come.
Experience in these sub-tropical countries shows the absolute necessity of having, for successful irrigation, also a system of thorough drainage.
The first impression of a great alluvial plain is that it is absolutely flat, with no drainage at all.
Before the systematic conversion of a tract into water-meadows can be safely determined on, care must be taken to have good drainage, natural or artificial, a sufficient supply of water, and water of good quality.
It might indeed have been thought that thorough drainage would be unnecessary, but it must be noted that porous subsoils or efficient drains do not act merely by carrying away stagnant water which would otherwise cool the earth, incrust the surface, and retard plant growth.
Some of the best water-meadows in England have but a thin soil resting on gravel and flints, this constituting a most effectual system of natural drainage.
Amongst causes of variation in the quantity of water needed will be its quality and temperature and rate of flow, the climate, the season, the soil, the subsoil, the artificial drainage, the slope, the aspect and the crop. In actual practice the amount of water varies from 300 gallons per acre in the hour to no less than 28,000 gallons.
River water, especially that which has received town sewage, or the drainage of highly manured land, would naturally be considered most suitable for irrigation, but excellent results are obtained also with waters which are uncontaminated with manurial matters, and which contain but 8 or io grains per gallon of the usual dissolved constituents of spring water.
The mixture of seeds for sowing a water-meadow demands much consideration, and must be modified according to local circumstances of soil, aspect, climate and drainage.
Beneath each cap, and near the upper end of the shaft, are a number of vertical slits through which the drainage water which rises passes out into the conduit or trench from which the irrigating streams originate.
In the ordinary English system of upward or drainage irrigation, ditches are dug all round the field.
The practice of irrigating differs in different places with differences in the quality of the water, the soil, the drainage, &c. As a general rule, when the irrigating season begins in November the water may flow for a fortnight continuously, but subsequent waterings, especially after December, should be shortened gradually in duration till the first week in April, when irrigation should cease.
The great Cavour canal is drawn from the left bank of the Po a few miles below Turin, and it is carried right across the drainage of the country.
Like the Cavour canal, the Villoresi is taken across the drainage of the country, entailing a number of very bold and costly works.
In the earlier section of this article it is explained how necessary it is that irrigation should always be accompanied by drainage.
This canal was badly constructed, and by entirely blocking the drainage of the valley did a great deal of harm to the lands.
In these years, too, owing to the extension of drainage works, the irrigable area of Egypt was greatly enlarged, so that if perennial cultivation was at all to be increased, it was necessary to increase the volume of the river, and this could only be done by storing up the flood supply.
He learned practical engineering at Middlesborough-on-Tees, and about 1850 invented a mechanical system for the drainage of land.
It has narrow streets badly paved and drained, and made still more dirty and offensive by the surface drainage of the upper town.
Since the British occupation in 1882 much has been done to better this state of things, notably by a good water-supply and a proper system of drainage.
Large sums were so advanced for the purposes of drainage and irrigation and other public works, and in relief of taxation.
The work is conducted on a regular system of fen colonization, the first operation being directed towards the drainage of the country.
This is effected by means of drainage canals cut at regular intervals and connected by means of cross ditches.
These draining ditches all have their issue in a main drainage canal, along which the transport of the peat and peatlitter takes place and the houses of the colonists are built.
Or the stream by cutting into another stream (piracy), but cutting through a barrier near its head waters, by entering a region of looser or softer rock; and by glacial drainage, may form a flood plain simply by filling up its valley (alluviation only).
When the drainage system has ceased to act or is entirely diverted owing to any cause, the flood plain may become a level area of great fertility, similar in appearance to the floor of an old lake.
Deposits of rock-salt have evidently been formed by the evaporation of salt water, probably in areas of inland drainage or enclosed basins, like the Dead Sea and the Great Salt Lake of Utah, or perhaps in some cases in an arm of the sea partially cut off, like the Kara Bughaz, which forms a natural salt-pan on the east side of the Caspian.
Drainage works were continued, roads cut, and other improvements effected during the 9th century.
The difference of the general level on the two sides of the water-parting is reflected in the length of their streams. On the west the drainage empties itself into the Atlantic after flowing only a very few miles, on the east it has to run 30 or 40 m.
Distinguished especially by the smoothness of their surface, they may be regarded as a roiling tableland or moorland, traversed by many valleys conducting the drainage to the sea.
Here again the longest slope is on the east side, where the Tweed bears the whole drainage of that side into the sea.
It should be noted that, according to Scottish usage, police " includes drainage, the suppression of nuisances, paving, lighting and cleansing, in addition to the provision of a constabulary force, and that in point of fact, paradoxical as it appears, the bulk of the police burghs do not manage their police.
The city has gas and electric illumination, street and suburban railways, drainage and a public water supply drawn from a small tributary of the Beberibe about 7 m.
Throughout the plains of Afghan Turkestan the drainage from the southern hills is arrested and lost in the desert sands.
The drainage basin of the Guayas, according to Theodor Wolf, covers an area of 14,000 sq.
The new town, or southern part, is the business and residential quarter of the better classes, but the buildings are chiefly of wood and the streets are provided with surface drainage only.
The drainage of Illinois is far better than its low elevation and comparatively level surface would suggest.
The dampness and miasma, to which so many of the early settlers' fatal "chills and fever" were due, have practically disappeared before modern methods of sanitary drainage.
From the foot of the Unai pass it follows the Kabul river, and from the foot of the Shibar it follows the circuitous route which is offered by the drainage of the Ghorband valley to Charikar, and thence southwards to Kabul.
These rivers collect the drainage of the northern slopes of the Himalayas, and convey it, by long and tortuous although opposite routes, into India.
The third river system of northern India receives the drainage of their southern slopes, and eventually unites into the mighty stream of the Ganges.
The drainage from the northern or Vindhyan edge of the three-sided table-land falls into the Ganges.
The drainage has therefore to make its way across India to the eastwards, now turning sharply round projecting ranges, now tumbling down ravines, or rushing along the valleys, until the rain which the Bombay sea-breeze has dropped upon the Western Ghats finally falls into the Bay of Bengal.
Port Louis, which is governed by an elective municipal council, is surrounded by lofty hills and its unhealthy situation is aggravated by the difficulty of effective drainage owing to the small amount of tide in the harbour.
The drainage finds its way to the Irrawaddy by three main streams (the Pwon, Ma-htun and Ma-de) on the west, and by two (the Kye-ni and Hput) on the east.
The streets are well paved and have sufficient slope at all points to give easy surface drainage; Montevideo has the reputation of being one of the cleanest cities of the world.
Numerous smaller channels seam the whole face of the country carrying off the surplus drainage in the rains, but drying up in the hot season.
Arkansas lies in the drainage basin of the lower Mississippi, and has a remarkable river system.
Through this passes the entire drainage of the interior.
The drainage basin measured from the water-partings of the enclosing mountains is some three times as great.
Another peculiar and very general feature of the drainage system of the state is the presence of numerous so-called river " sinks," where the waters disappear, either directly by evaporation or (as in Death Valley) after flowing for a time beneath the surface.
Tulare lake, which with Buena Vista lake and Kern lake receives the drainage of the southern Sierra, shows extreme local variations of shore-line, and is generally believed to have shrunk extremely since 1850, though of this no adequate proof yet exists.
The drainage of Lassen, Siskiyou and Modoc counties has no outlet to the sea and is collected in a number of great alkaline lakes.
They have no drainage to the sea, save fitfully for slight areas through the Colorado river.
In the great lacustrine depression of Nicaragua is collected all the drainage from the eastern versant of the volcanic mountains, from the sheer western escarpment of the main cordillera, and from a large area of northern Costa Rica.
The exemption was attributed to cleanliness and good drainage.
Again, in Oporto there is an area which combines every possible sanitary defect - dense overcrowding, great poverty, no light, no air, no drainage, no scavenging, water brought in buckets.
The ideal soil for vinegrowing is that which possesses a sufficiency, but not an excess, of nutriment for the plant, and which is so constituted that it will afford good drainage.
The drainage system of the state is naturally very complicated.
The Deoha is another great drainage artery and receives many minor streams. The Gomati or Gumti also passes through the district.
In the plains where drainage is poor, especially in the S., the soils contain too much alkali; but in the highlands most of this has been dissolved and carried away by the rains, and the soils are well adapted for grazing grounds.
Its drainage area, which includes the whole of middle and eastern as well as part of south-eastern Russia, amounts to 563,300 sq.
They also pay great attention to drainage and general cleanliness.
Its excellent drainage makes street grading an easy matter.
When the industry was first established, the land which was supposed to be best for the plant was hill or undulating ground; but now it has been found in the Surma valley that with good drainage the heaviest crops of tea can be raised from low-lying land, even such as formerly supported rice cultivation.
The other drainage arteries are all small, but many in number; while lakes and marshes aggregate fully 222% of the total surface.
The Angerman receives the waters of a wider system of streams and lakes than the rivers north of it, and has thus a drainage area of 12,591 sq.
South of the Toro there are no large rivers on this coast, but the narrow fjords penetrate deeply into the mountains and bring away the drainage of their snow-capped, storm-swept elevations.
The third drainage area comprises Persian Seistan with part of the Helmund (Hilmend) basin and a considerable tract adjoining it on the west.
The fourth is a comparatively small area on the western frontier containing the basin of Lake Urmia, shut off from the rest of the inland drainage, and the fifth area takes in a part of Baluchistan, most of Kermgn, a part of Fars, all Yezd, Isfahan, Kashan, Kum, Irak, Khamseh, Kazvin, Teheran, Samnan, Damghan, Shahrud, Khorasan and the central desert regions.
The Herhaz, though not important in length of course or drainage, also, like the Seafid Rud, breaks through the Elburz range from the inner southern scarp to the north.
The drainage of the rivers which have no outlet to the sea and form inland lakes and swamps (kav-ir) may be estimated at 350,000 sq.
In the south the drainage is to the Atlantic, chiefly through the Orange River, in the north to the Indian Ocean through the Zambezi, Limpopo and other streams. A large number of smaller rivers rise on the outer slopes of the mountain ramparts and flow direct to the sea.
Here all the main drainage either runs northwards to the Gomal, passing through the uplands that lie west of the Suliman Range; or it gathers locally in narrow lateral valleys at the back of these mountains and then bursts directly eastwards through the limestone axis of the hills, making for the Indus by the shortest transverse route.
Here, throughout the elevated highlands of the Kalat plateau which are called Jalawan, the drainage gathers into channels which cut deep gorges in the hills, and passes eastwards into the plains of Sind.
Between the Takht Mountain and the Siwaliks, the intervening belt of ridge and furrow has been greatly denuded by transverse drainage - a system of drainage which we now know to have existed before the formation of the hills, and to have continued to cut through them as they gradually rose above the plain level.
The point of this desert inlet receives the drainage of two local basins, the Bolan and the Nari.
The drainage of the Bolan and Nari finally disappears in the irrigated flats of the alluvial bay (Kach Gandava), which extends 130 m.
Within this area the drainage generally trends south Southern .
To the south-west are the long sweeping valleys of Rakshan and Panjgur, which, curving northwards, likewise discharge their drainage into the Mashkel.
Throughout this vast space of elevated plateau and mountain face geologists now trace a system of main chains, or axes, extending from the Hindu Kush to Assam, arranged in approximately parallel lines, and traversed at intervals by main lines of drainage obliquely.
Recent investigations show that all the chief rivers of Nepal flowing southwards to the Tarai take their rise north of the line of highest crests, the " main range " of the Himalaya; and that some of them drain long lateral high-level valleys enclosed between minor ridges whose strike is parallel to the axis of the Himalaya and, occasionally, almost at right angles to the course of the main drainage channels breaking down to the plains.
The reason assigned for these extraordinary diversions of the drainage right across the general strike of the ridges is that it is antecedent - i.e.
The straits of the Jhelum, below Baramulla, probably account for the lovely vale of Kashmir, which is in form (if not in principles of construction) a repetition on grand scale of the Maidan of the Afridi Tirah, where the drainage from the slopes of a great amphitheatre of hills is collected and then arrested by the gorge which marks the outlet to the Bara.
The great drawback to this region is defective drainage; the streams have too sluggish a current to carry off the water in the rainy season.
The south-east drainage basin, which is smaller and economically less important than that of the Madeira, discharges into the Paraguay and extends from the Sierras de Chiquitos south to the Argentine frontier, and from the Cordillera Oriental east to the Paraguay.
The third drainage basin is that of the great central plateau, or alta-planicie.
The drainage of this extensive district seems to be wholly absorbed by the dry soil of the desert and by evaporation.
They fill slight depressions and are caused by defective drainage.
There is a further supply obtained from three reservoirs of a combined capacity of 513,000,000, constructed in 1866, 1874 and 1889 respectively in the Lliw and adjoining valleys, in the drainage area of the Loughor, about 10 m.
Their jurisdiction extends to watersupply, the drainage, lighting and cleaning of the streets, the care of the poor, hospitals and schools.
The drainage system is elaborate, and has stood the test of time.
The city is divided into twelve radial systems, each with a pumping station, and the drainage is forced through five mains to eighteen sewage farms, each of which is under careful sanitary supervision, in respect both of the persons employed thereon, and the products, mainly milk, passing thence to the city for human consumption.
Only in a few isolated cases has any contamination been traced to fever or other zymotic germs. In this connexion it is worth noting that the infectious diseases hospital has a separate system of drainage which is carefully disinfected, and not allowed to be employed for the purposes of manure.
The two most important works undertaken by the old municipality were the provision of a supply of filtered water and the construction of a main drainage system.
The climate of the city was originally very unhealthy, but it has improved greatly of recent years with modern sanitation and drainage.
Some parts of it lay below high-water mark on the Hugli, and its low level throughout rendered its drainage a most difficult problem.
On the north their drainage forms the Luni and Sakhi rivers, which fall into the Gulf of Cutch.
To the south, their drainage supplies two distinct river systems, one of which debouches in comparatively small streams on the Gulf of Cambay, while the other unites to form the Chambal river, a great southern tributary of the Jumna, flowing thence via the Ganges, into the Bay of Bengal on the other side of India.
At long intervals, however, a fertile tract marks some great natural line of drainage, and among such valleys Ajmere city, with its lake, stands conspicuous.
Commercially, however, this stream is less important than the Passaic. In the southern half of the state the drainage is simple, and the streams are unimportant, flowing straight to the Delaware or the Atlantic. The westward streams are only small creeks; the eastward and southward streams, however, on account of the wider slope, have greater length.
The Fens, the flat open levels in the lower basins of the Witham, Welland, Nene and Great Ouse, only kept from their former marshy conditions by an extensive system of artificial drainage, and the similar levels round the head of the Humber estuary, differ completely in appearance from the higher and firmer parts of the plain.
The variations in length of the general slope of the land towards successive natural divisions of the coast may be illustrated by a comparative table of the mileage and drainage areas of the principal English rivers.
It forms a roughly circular highland area, the drainage lines of which radiate outward from the centre in a series of narrow valleys, the upper parts of which cut deeply into the mountains, and the lower widen into the surrounding plain.
The Fossdyke in Lincolnshire, connecting the river Trent at Torksey with the Witham near Lincoln, and now belonging to the Great Northern and Great Eastern joint railways, is usually indicated as the earliest extant canal in England, inasmuch as it was constructed by the Romans for the purpose of drainage or water-supply, and must have been used for navigation at an early period.
There is some traffic on the navigable drainage cuts and rivers of the Fens, but beyond these, in a broad consideration of the waterways of England from the point of view of their commercial importance, it is unnecessary to go.
In the event of the borough fund being more than sufficient to meet the demands upon it without recourse to a borough rate, any surplus may be applied in payment of any expenses of the council as a sanitary authority or in improving the borough or any part thereof by drainage, enlargement of streets or otherwise.
It may be pointed out here that these expressions are defined by the act, the effect of the definitions being shortly that a drain is a conduit for the drainage of one building or of several within the same curtilage, while a sewer comprises every kind of drain except that which is covered by the definition of a drain as above stated.
For the most part it has reference only to what is called a special drainage district, that is to say, a district formed out of one or more parishes or parts of parishes for the purpose of the provision of a common water-supply, or scheme of sewerage, or the like, and in the event of such a district including part only of a parish, the remaining portion would, so far as the special expenses for which the district was created are concerned, be a separate contributory place.
These exist for the purpose of regulating drainage, and providing defence against water in fen lands or lands subject to floods from rivers or tidal waters.
The commissioners derive their authority from the Sewers Commission Acts, which date from the time of Henry VIII., from the Land Drainage Act 1861, and from various local acts.
At the head of Lynn Canal, the only place on the whole extent of the south-eastern Alaskan coast where a clear-cut waterparting is exhibited between the sea-board and interior drainage, the summits of the highest peaks in the Coast Range are 8000 to 9000 ft.
The Yukon is one of the great drainage systems of the world.
The willows in the Arctic drainage basin shrink to shrubs scarcely knee-high.
The glacier or ice sheet overran all Maine, irregularly scouring out the bed rock to produce rock basins, damming up many river valleys with glacial deposits and completely disarranging the drainage lines.
In conjunction with the regulation of the river Raab, and the drainage of the Hansag marsh, plans for the drainage of the lake have been proposed.
On the other hand, it is interesting to compare the arrangement of the drainage waters of the Caucasus with those of the Alps.
The Lyakhva and Aragva, tributaries of the Kura, carry off the waters of the main range south of Kasbek, and other tributaries, such as the Yora and the Alazan, collect the surplus drainage of the main Caucasus range farther east.
Such are the Takazze in the north, the Abai in the centre, and the Sobat in the south, and through these three arteries is discharged about four-fifths of the entire drainage.
Drainage and sanitary arrangements do not exist.
The western members of the high plateaus drain into the Great Basin for the most part, and in this drainage system the Sevier river is perhaps most prominent.
In the meantime much antiquated legislation which tended to restrict trade and industry was abolished; roads, canals and drainage works were carried out.
The gentle declivity of the surface and the porous character of the prevailing sandstone formation render the drainage excellent.
In the northern districts the rivers run along the valleys, receive the drainage from the country on !l either side, absorb broad tributaries and rush forward with an ever-increasing volume.
The drainage of the state is wholly into the Mississippi, directly or indirectly, and almost wholly into either that river or the Missouri within the borders of the state.
The Pacific coast rivers are numerous, and discharge a very large volume of water into the ocean in proportion to the area of their drainage basins, because of the heavy rainfall on the western slopes of the Coast range.
The four intendencias are called Goajira, Meta, Alto Caqueta and Putumayo, and their aggregate area is estimated to be considerably more than half of the republic. The first covers the Goajira peninsula, which formerly belonged to the department of Magdalena, and the other three roughly correspond to the drainage basins of the three great rivers of the eastern plains whose names they bear.
He also carried out considerable works in relation to the Nene Valley drainage and the reclamation of land at the Norfolk estuary.
South of the inner chain the drainage is direct to the Atlantic or Indian Oceans.
At the height of the season the town is much overcrowded, and the entire want of a drainage system is severely felt.
In English it has been called indifferently the " catchment basin," the " gathering ground," the " drainage area " and the " watershed."
If any observations exist upon the drainage area itself they are commonly only from a single gauge, and this gauge, unless the area is very level, may give results widely different from the mean fall on the whole area.
The ordinate to any point upon this curved line then represents on the left-hand scale the maximum continuous yield per day for each acre of drainage area, from a reservoir whose capacity is equal to the corresponding abscissa.