"When the dikes enclosing the lake were completed, the engineers set up three very powerful steam engines, and gave to each one ten or twelve enormous pumps to work. These pumping engines were made on such a grand scale that they lifted over sixty tuns of water at every stroke. But yet so large was the lake, and so vast the quantity of water to be drained, that though there were three of the engines working at this rate, and though they were kept at work night and day, it took them a year and a half to lay the ground dry. The work was, however, at last accomplished, and now, what was the bottom of the lake is all converted into pastures and green fields. But they still have to keep the pumps going all the time to lift out the surplus water that falls over the whole space in rain. You may judge that the amount is very large that falls on a district thirty miles round. They calculate that the quantity which they have to pump up now, every year, in order to keep the land from being overflowed again, is over fifty millions of tuns. And that is a quantity larger than you can ever conceive of.
"And yet the piece of ground is so large, that the cost of this pumping makes only about fifty cents for each acre of land, which is very little.
"Besides these great spreading inundations, which Holland has always been subject to from the lakes and rivers in the middle of the country, there has always been a greater danger still to be feared from the ice freshets of the Rhine, and other great rivers coming from the interior of the country. The Rhine, you know, flows from south to north, and often the ice, in the spring, breaks up in the middle of the course of the river, before it gets thawed in Holland. The broken ice, in coming down the stream towards the north, is kept within the banks of the stream where the banks are high; but when it reaches Holland it is not only no longer so confined, but it finds its flow obstructed by the ice which there still remains solid, and so it gets jammed and forms dams, and that makes the water rise very fast. At one time when such a dam was formed, the water rose seven feet in an hour. At such times the pressure becomes so prodigious that the dikes along the bank of the river are burst, and water, sand, gravel, and ice, all pour over together upon the surrounding country, and overwhelm and destroy every thing that comes in its way.
"Some of the inundations caused in Holland by these floods and freshets have been terrible. In ancient times they were worse than they are now; because now the dikes are stronger, and are better guarded. At one inundation that occurred about sixty years ago, eighty thousand persons were drowned. At another, three hundred years earlier, one hundred thousand perished. Think what awful floods there must have been.
"But I cannot write any more in this letter. I have taken up so much space and time in telling you about the inundations and freshets, that I have not time to describe a great many other things which I have seen, that are quite as curious and remarkable as they. But when I get home I can tell you all about them, in the winter evenings, and read to you about them from my journal.
"Your affectionate brother,
"George."
Rollo's Letter.
"Leyden, Tuesday, September 27.
"My Dear Mother:
"Uncle George and I are having a very fine time indeed in travelling about Holland; it is such a funny country, on account of there being so many canals. The water is all smooth and still in all the canals, (except when the wind blows,) and so there must be excellent skating every where in the winter.