« 上一頁繼續 »
the dyke must have been overflowed, and perhaps have given way, and Amsterdam would have suffered a calamitous inundation. Fortunately, in a moment when the danger was most urgent, the tide stopped, and the great pressure was immediately diminished and removed from the sea-wall; but the lower part of the town had already been laid under water. The injuries done at that time in the province of Holland were immense; but by Dutch industry all the damage was repaired within 2 years. (Gedenkboek van Neerlands Watersnood, in Feb. 1825, door J. C. Beijer, 2 vols. 8vo. te s' Gravenhage, 1826. It contains a notice of the more remarkable recorded floods in the Netherlands from the commencement of the Christian era to the great flood of 1825.) The arms of one of the United Provinces is a lion swimming, with the motto, Luctor, et emergo, "I strive, and keep my head above water.' It might be generally applied to the whole country, which has to maintain a perpetual struggle for existence against difficulties never to be entirely removed. The inhabitant of the provinces bordering on the sea, or the Rhine, constantly threatened with the danger of submersion, is not more secure than he who dwells on the side of Etna, or at the foot of Vesuvius, with a volcano heaving beneath him. A stranger can have a full impression of this only when he walks at the foot of one of those vast dykes, and hears the roar of the waves on the outside, 16 or 20 feet higher than his head. Some parts of the country lie several feet below the actual bed of the Rhine; as for instance, the Ablasserwaard, near Gorcum. Indeed, the industry of the early inhabitants of Holland in restraining their rivers between dykes, so as to prevent periodical inundations, threatens their descendants with a serious calamity at no distant period. It is the nature of all rivers liable to inundation to deposit great part of the sullage on their immediate banks, and raise them higher than the morass behind. Their beds, too, are continually raised by the deposit of the earthy particles mechanically suspended in the water. Hence the Rhine and other great rivers now flow along the ridges of great causeways or natural embankments formed of the deposit brought down by them in the course of ages, and far higher than the surrounding country. This must in all probability be broken through some day or other, and the Rhine will find a new outlet to the sea. The same effect may be seen in the Po and Adige. See Handbook for N. Italy, p. 368.
The expense of maintaining the dykes is supported by taxes levied by com missioners appointed for the purpose.
Holland is so intersected with canals, that to a person looking down upon it from a balloon they would have the appearance of a network extending from one end of the country to the other. They serve, 1st, as the means of communication; every little town and village having its own system of canals, which connect it with all the places around. 2dly, as drains to carry off the superfluous water of the country. 3dly, in the place of walls and hedges: fields, gardens, and houses are surrounded by canals or moats, as in other countries by fences; and they afford an equally good protection.
The canals differ considerably from those of England, which are measured out so as barely to admit two narrow barges to pass, and interrupted at short distances by locks. In Holland, as the canal is the drain as well as the highway of the country, and rids the land of its superabundant moisture, there is no restriction to its breadth; and as there is little variation of level, few locks are required: but those canals which empty themselves into the sea are provided with sluice-gates to prevent the influx of the tides, which are often higher than the waters of the canal itself.
The several heights of the waters of Holland are referred to the Amsterdam
Pile, which is considered to have been the mean height of the water in the Y in the century before last, but that high water is now 2 or 3 inches above this level.
The principal canals are 60 ft. broad and 6 ft. deep. Not only the surface, but even the bottom, is frequently higher than the adjoining land. The North Holland ship canal is truly one of the marvels of the country, and should be viewed by every traveller who visits Amsterdam. In its dimensions it is the largest not only in Holland, but in Europe (Route 3.).
The discovery of the lock, an invention altogether modern, and which has given an entirely new feature to the inland navigation of Europe, has been claimed both by the Italians and the Dutch. "There is strong reason to believe that in Holland the lock was known, and in use, at least a century before its application in Italy."-Telford: Edin. Cycl. Inclined planes for transferring vessels from one level to another, similar to those in China, under the name of rolling bridges, have been long known in Holland. The object seems to have been, not so much to overcome a difference of level, as to prevent the transference of water from one tract of country to another, on account of the jealousy of drainage. One of the most remarkable of this kind is the Overtoon, between Amsterdam and the Haarlem Meer, which is preferred, on account of the interest which the city of Haarlem has in continuing the ship navigation through the ancient sea sluices of Sparendam. (On the subject of this section, see the article "Navigation Inland," in the Edin. Cycl. It was contributed by the celebrated engineer Telford.)
Polder is the name given to a piece of ground below the level of the sea or river, which having once been a morass or lake (plas, Anglice, plash), has been surrounded by embankments, and then cleared of the water by pumps. So large a part of Holland and Belgium was originally in the condition of morass, that whole districts are composed entirely of polders partitioned off by dykes or ramparts; and the ground thus drained is usually remarkable for its richness and fertility. Many of the polders in the Rhynland, or district around Leiden, are 32 ft. below the sea.
Besides the natural lakes, the extent of surface covered by water has been much increased by digging for fuel. The natural fuel of the Netherlands is peat, the brown spongy peat obtained from the higher bogs (hooge veenen, or fens) of Friesland, and the black, solid, and more earthy peat of the low mosses (laage veenen) of North Holland. The surface of the bogs of the latter country is rarely above the level of the sea. From Rotterdam to the Helder they cover a very large area, and have proved rich mines of fuel for many ages. But where the peat was extracted stagnant water took its place. Scooped up from beneath this gathering water as long as any available turf existed, or as long as it could easily be reached, the quaking bogs were succeeded by lakes, often from 12 to 20 ft. deep below low water, sometimes of considerable extent, scattered in numbers over the country, and frequently separated only by narrow intervals of unsteady land between.
In draining one of these morasses, or inland seas, and rendering it fit for cultivation, the first operation consists in damming it in with a rampart of earth sufficiently strong and high to prevent foreign water from flowing into it. side this rampart or dyke a ringsloot or surrounding drain is made, of dimen sions sufficient to be a navigable canal. Windmills are then erected on the edge of the dyke, each of which works a water-wheel. Pumps are very seldom used in draining, as the water is usually highly charged with silt, and is not required to be raised a very great height. The instruments employed are, the scoopwheel, the screw of Archimedes, and the inclined scoop-wheel, or Eckhardt
wheel. When a great undertaking of drainage is going on, houses are erected in a convenient situation on the dyke, where the engineers and a committee of the proprietors constantly reside, and carefully watch the progress which the windmills are making. In most cases the undertakers are compelled by government regulations to complete the drainage at a certain period of the year; for the very obvious reason that, if the ground were not cleared of the water until the beginning of the summer heat, the exhalations would materially increase the marsh fevers, which generally prevail in the first years of an extensive drainage.
The mills raise the water from the marsh to the ringsloot or canal, which conveys it to a river or to the sea. But most frequently the whole of this great operation cannot be performed at once: and where the marshes are of too great a depth below the surrounding country, 2 or 3 dykes and as many canals are made, at different levels, rising by degrees to the upper canal, in which the whole terminates. In the Schermer-Meer, for instance, there are four stages of canals. Every piece of ground forms a long parallelogram, separated from the next by a broad deep ditch, which, in reality, is a first canal. This serves
to convey part of the harvest; to carry off the water which, but for this, would continue on the ground; but, above all, as an inclosure, which renders it unne cessary to guard the flocks, which seldom attempt to pass over this obstruction. The canals communicate, by means of the above-mentioned mills, with those of the second stage along the roads; lastly, two or three upper canals traverse the whole of the polder, like great arteries, carrying all these lower waters into one grand canal made below the dyke, and immediately connected with the sea. These canals, on 4 different levels, are, in general, completely separated, but are made to communicate whenever it is desired, and the precise proportion which is thought necessary may be established between them.
"It is easy to conceive the extreme fertility acquired by land managed in this manner. Formed originally of mud, which was itself rich, it is covered almost all the year round with herbs which contribute to its fertility. All the water which might be injurious is drawn off at pleasure, by means of the mills, and a regular and gradual irrigation is introduced at the most favourable
"The appearance of the polder itself, when you have got into it, is very different from the upper country; and, though more remarkable, it is decidedly less agreeable. Each object reminds you that you are at the bottom of a lake, on a factitious soil, where every thing is calculated. When the draining is finished, the undertakers have very regularly portioned out the conquest they have made from the waters; they have divided and subdivided it into perfectly equal parts; they have dug canals, made roads, planted trees in perfect right lines, proscribed all curves, all variation in the distance, and placed at the head of each farm a square habitation, which is always similar to its neighbour. Very accurately surrounded with 20 trees, often fine, but never graceful, these redoubts resemble neither farm-houses, which would be less carefully kept, and more animated, nor country seats, where something could be dedicated to pleasure. Their large roofs, coming down nearly to the ground in 4 equal slopes, rest upon brick walls, which are always neat, but never elegant. They look as if they had just sprung up like mushrooms among the tufted grass which surrounds them, and which seems never to have been trodden under foot.". A Journey in North Holland.
In forming an idea of the power which will be required to bale out the water from a lake, or to maintain it in the state of a polder, 3 considerations are to be taken into account: 1st, the depth of water in the lake at its mean level, which indicates the power necessary merely to drain the lake; 2dly, the average yearly fall of rain and average yearly evaporation, the difference being
to be removed by pumping; lastly, the quantity of spring or ooze water likely to make its way into the hollow land.
An excellent opportunity will be afforded to the traveller to view the processes of a drainage on the very largest scale in the operations now in progress for emptying the great Lake of Haarlem (Route 2.).
The better class of polders, with a good soil, when richly manured, and carefully cleared of weeds, especially those recently redeemed from the sea, are of great value, and highly productive as arable land; but the greater part furnish pasture or hay for the cattle, and are by no means of inferior value in this grazing country.
Many polders are subjected to annual inundations in the winter time, which, however, do no harm, if the water which covers them be not salt, and provided it can be removed by the end of May. The proprietors of the polders pay a certain sum to be permitted to discharge the water pumped out of them into the neighbouring canals.
It may, at first sight, appear singular that the polders, the source of agricul tural wealth, should be equally important to the country in a military point of view; this is, however, the case. By opening the sluices, cutting the dykes, and inundating the low meadows they enclose-a measure fraught with ruin, and therefore only resorted to at the last extremity, -the Dutch may bid defiance to the strongest force brought against them; as, though the depth of water and mud upon a submerged polder is sufficiently great to check the advance of an army, it is too shallow to admit the passage of any but small boats. It is true, that a hard frost sometimes converts the water, which serves as a defence in summer, into a bridge for the invading foes in winter. By availing themselves of the desperate resource of drowning the land to save it, the Dutch purchased their freedom from the yoke of Spain; and Europe beheld with astonishment the most powerful monarch in the world, upon whose dominions the sun never set, baffled by the hardy efforts of the inhabitants of a country which in extent is not much greater than Yorkshire. In a following age, 1672, at a time when most of the provinces had opened their gates in consternation to Louis XIV., Holland opened to him her sluices, and was thus preserved from French tyranny. She has made the same sacrifice with equal success at various other periods of her history; and even in 1830-32 every thing was prepared to inundate the country, in the event of an inroad of the French army into Holland, which was at that time threatened.
The Dunes, or sand-hills, which extend along the coast of Holland from Dunkirk, nearly without interruption, to the Helder, varying in breadth between 1 and 3 miles, and rising sometimes to 40 or 50 ft. in height, are formed entirely by the action of the wind blowing up the sand of the sea-shore; they are a source of good and evil to the country; they serve as a natural barrier to keep out the ocean; a benefit which, but for the ingenuity and contrivance of man, would be more than counterbalanced by the injury done by their progress inland. On the sea-shore they are mere loose heaps, driven about by every blast, like snow-wreaths on the Alps; and, were they not restrained, would move onward year after year, and inundate the country. In passing over a desert of this kind at Schevening, on a windy day, the atmosphere appears dim with the particles of sand blown like smoke through the air. The height of the dunes depends upon the fineness of the sand, as the wind has, of course, the most power in transporting the minuter particles. Camperdown, memorable in the naval annals of Britain, is one of the loftiest on the whole coast, owing to this
To check the dispersion of the sand, and the evil attending it, the dunes are
sowed regularly every year with plants congenial to it, for even sand has a vegetation peculiar to itself, which may be called luxuriant: but a species of coarse reed-grass, or seabent, which grows near the sea (Marum, Arundo arenaria), whose roots sometimes spread to a distance of 30 ft., is principally employed, and to greatest advantage. In a short time the roots spread and combine, so as to hold fast the sand, and cover the surface with a succession of verdant vegetation, which, growing and decaying on it, accumulates upon it a layer of earth capable at length of producing a crop of excellent potatoes, and even of supporting plantations of firs. Most of the plants thus cultivated on the Dunes may be seen in the Botanic Garden at Leyden.
Before the attempt was made to arrest the progress of the sand, it had advanced, in the course of centuries, far into the interior; and it has recently been found worth while, in some instances, to dig away and remove the superincumbent hillocks, and lay bare the good soil buried by them: since, on being again exposed to the air and light, it is found to be still fertile and productive. (As to the subjects treated of in Sections 8-12., see Art. VI. Edin. Rev., Oct. 1847, vol. lxxxvi. p. 419.)
13. GARDENS AND SUMMER-HOUSES.
Though the charm of variety of aspect and inequality of surface has been denied by nature to Holland, compensation is made for this, in a certain degree, by the high cultivation of its fields and gardens. In whatever direction the traveller passes through the country, and whether by road or canal, he will find the way enlivened by country seats (buiten plaatsen) and pleasure-gardens; in the laying out and maintaining of which great wealth is expended, though they do not always show much taste. They present the most perfect pictures of prettiness, with their meandering walks and fantastically cut parterres, filled with flowers of gaudiest hue. If possible, each garden is provided with a fish-pond; and, if it be wanting, the first step which a Dutch proprietor invariably takes, upon entering a newly-acquired demesne, is to dig a large hole that he may convert into a pond; so great an attachment does he appear to have for that element which surrounds him on all sides, which is never out of his sight, and which invariably stagnates before his door in the shape of a canal. At the extremity of the garden a pair of iron gates is erected, often more for ornament than use. Through these, or through a gap made purposely in the hedge, the passer-by is admitted to spend his admiration on the beauties within, -on the pyramids of flower-pots, trim box borders, and velvet lawns and grass-plots. At the very end of the garden, overlooking the high road or canal, a summer-house is always placed, called zomerhuis (summer-house), tuin huis (garden-house), or koepel (cupola); this is the resort of the family in spring and summer afternoons. Here the men smoke their pipes and sip their beer, coffee, or tea; the old ladies ply the knitting-needle, and the young ones amuse themselves with eyeing and criticising the passers-by. In the neighbourhood of all the large towns, the citizens and tradespeople, who have their shops and counting-houses in the crowded and narrow streets, generally have such a pavilion in a small garden on the outskirts, even though they have no house attached to it, to which they can retire when the business of the day is over. Very frequently, on entering the town, the traveller passes through a whole street of such gazabos. By a peculiarity of taste, they are invariably placed in a stagnant ditch, which is usually covered with a luxuriant crop of green duckweed, and often offends the nose by the noisome odours which it exhales. The consequence is, that ere the sun goes down, however warm the evening, these ditch-bestriding pleasurehouses must be abandoned to the neighbourly frogs; and they who should venture to prolong their evening recreations beyond a certain hour, might pay