, are about six
feet wide. They are wide enough to prevent the cattle from jumping
across them, and so they serve for fences to divide the fields from each
other. They also serve for roads, for the Dutchmen use boats on their
farms to get in their hay and produce, instead of carts.

"The water that collects in these low canals and drains, which run
across the polders, cannot flow out into the large canals, which are
higher than they are, and so they have to pump it out. They pump it out
generally by means of wind mills. So wherever you go, throughout all
Holland, you find an immense number of wind mills. These wind mills are
very curious indeed. Some of them are immensely large. They look like
lighthouses. The large ones are generally built of brick, and some of
them are several hundred years old. The sails of the big ones are often
fifty feet long, and sometimes eighty feet. This makes a wheel one
hundred and sixty feet in diameter. When you stand under one of these
mills, and look up, and see these immense sails revolving so high in the
air that the lowest point, when the sail comes round, is higher than the
tops of the four story houses, the effect is quite sublime.

"With these wind mills they pump the water up from one drain or canal to
another, till they get it high enough to run off into the sea. In some
places, however, it is very difficult to get the water into the sea even
in this way, even at low tides. The River Amstel, for instance, which
comes out at Amsterdam, and into which a great many canals and channels
are pumped, is so low at its mouth that the sea is never, at the lowest
tides, more than a foot and a half below it. At high tides the sea is a
great deal above it. The average is about a foot above. Of course it
requires a great deal of management to get the waters of the river out,
and avoid letting the water of the sea in. They do it by immense
sluices, which are generally kept shut, and only opened when the tide is
low.

"In the mean time, if it should ever so happen that they could not
succeed in letting the water out fast enough, it would, of course,
accumulate, and rise in the rivers, and press against the dikes that run
along the banks of it, till at last it would break through in some weak
place; and then, unless the people could stop the breach, the whole
polder on that side would be gradually overflowed. The inundation would
extend until it came to some other dike to stop it. The polder th