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Rollo in Holland
Rollo in Holland
Chapter I.
Preparations
Holland is one of the most remarkable countries on the globe. The peculiarities which make it remarkable arise from the fact that it is almost perfectly level throughout, and it lies so low. A very large portion of it, in fact, lies below the level of the sea, the waters being kept out, as every body knows, by immense dikes that have stood for ages.
These dikes are so immense, and they are so concealed by the houses, and trees, and mills, and even villages that cover and disguise them, that when the traveller first sees them he can hardly believe that they are dikes. Some of them are several hundred feet wide, and have a good broad public road upon the top, with a canal perhaps by the side of it, and avenues of trees, and road-side inns, and immense wind mills on the other hand. When riding or walking along upon such a dike on one side, down a long slope, they have a glimpse of water between the trees. On the other, at an equal distance you see a green expanse of country, with gardens, orchards, fields of corn and grain, and scattered farm houses extending far and wide. At first you do not perceive that this beautiful country that you see spreading in every direction on one side of the road is below the level of the water that you see on the other side; but on a careful comparison you find that it is so. When the tide is high the difference is very great, and were it not for the dikes the people would be inundated.
Indeed, the dikes alone would not prevent the country from being inundated; for it is not possible to make them perfectly tight, and even if it were so, the soil beneath them is more or less pervious to water, and thus the water of the sea and of the rivers would slowly press its way through the lower strata, and oozing up into the land beyond, would soon make it all a swamp.
Then, besides the interpercolation from the soil, there is the rain. In upland countries, the surplus water that falls in rain flows off in brooks and rivers to the sea; but in land that is below the level of the sea, there can be no natural flow of either brooks or rivers. The rain water, therefore, that falls on this low land would remain there stagnant, except the comparatively small portion of it that would be evaporated by the sun and wind.
Thus you see, that if the people of Holland were to rely on the dikes alone to keep the land dry, the country would become in a very short time one immense morass.
To prevent this result it is necessary to adopt some plan to raise the water, as fast as it accumulates in the low grounds, and convey it away. This is done by pumps and other such hydraulic engines, and these are worked in general by wind mills.
They might be worked by steam engines; but steam engines are much more expensive than wind mills. It not only costs much more to make them, but the expense of working them from day to day is very great, on account of the fuel which they require. The necessary attendance on a steam engine, too, is very expensive. There must be engineers, with high pay, to watch the engine and to keep it always in order, and firemen to feed the fires, and ashmen to carry away the ashes and cinders. Whereas a wind mill takes care of itself.
The wind makes the wind mills go, and the wind costs nothing. It is true, that the head of the mill must be changed from time to time, so as to present the sails always in proper direction to the wind. But even this is done by the wind itself. There is a contrivance by which the mill is made to turn itself so as to face always in the right direction towards the wind; and not only so, but the mill is sometimes so constructed that if the wind blows too hard, it takes in a part of the sails by its own spontaneous action, and thus diminishes the strain which might otherwise be injurious to the machinery.
Now, since the advantages of wind mills are so great over steam engines, in respect especially to cheapness, perhaps you will ask why steam is employed at all to turn machinery, instead of always using the wind. The reason is, because the wind is so unsteady. Some days a wind mill will work, and some days it will lie still; and thus in regard to the time when it will do what is required of it, no reliance can be placed upon it. This is of very little consequence in the work of pumping up water from the sunken country in Holland; for, if for several days the mills should not do their work, no great harm would come of it, since the amount of water which would accumulate in that time would not do any harm. The ground might become more wet, and the canals and reservoirs get full,—just as brooks and rivers do on any upland country after a long rain. But then, after the calm was over and the wind began to blow again, the mills would all go industriously to work, and the surplus water would soon be pumped up, and discharged over the dikes into the sea again.
Thus the irregularity in the action of the wind mills in doing such work as this, is of comparatively little consequence.