Different from the industrial windmills at Zaanse Schans, that processed goods like oil, paint, perfume and mustard, were the polder windmills. These were used in 17th century Holland to pump water out of low areas and to reclaim land from water, that is, to make polders.
The first polder, or piece of land reclaimed from water, in Dutch history, was the Beemster.
The Amsterdam Windmill Tour includes this area in its itinerary.
The Beemster is located some 25 km / 16 miles North from Amsterdam.
It’s an area of 70 km² / 44 miles² and has currently around 9000 inhabitants.
400 years ago, a large lake covered that entire piece of land.
In 1610, a number of courageous entrepreneurs from Amsterdam, took on the risky enterprise to reclaim the Beemster lake. They had made a lot of money in world trade and were in search of profitable investments to grow their wealth even more.
The purpose of this project was to resolve the problem of the lake’s rising waters that threatened nearby villages and even Amsterdam. Moreover, the rapidly growing population of 17th century Holland needed to be provided with food. Therefore, new lands were needed for agriculture. As agricultural lands were scarce, once reclaimed, they could be leased or sold for very high prices.
And so it happened that the Beemster lake was reclaimed within 2 years (1610-1612).
(Beemster lake before and after reclamation)
How did the Dutch proceed to reclaim the Beemster lake?
First, a moat was dug all around the lake. Still existent today, the “Beemsterringvaart” canal has a circumference of almost 19 km / 11 miles. With the earth that was dug out of the canal, a dike was built around the lake. The dike, a large wall, had to prevent the waters that were pumped out, from flowing back into the lake.
All around, by the board of the lake, windmills were placed to pump out the water.
Unfortunately, none of the 50 windmills that were used to reclaim the Beemster lake are left today.
However, in the Schermer, the adjacent area that was reclaimed after the Beemster, the windmills are still there. I took some pictures of one of them to illustrate the working of the polder windmills.
(Windmill at Schermer)
The windmill’s sail, moved by the wind, activates a screw pump.
(Screw pumps of Schermer windmill)
Positioned at the bottom of the windmill, the screw pumps the waters from the backside of the windmill, facing the low land, the polder, up to the higher front side of the windmill.
(Waters flowing from high side of the Schermer windmill into a moat)
Each windmill had the capacity of pumping the water up 1,5 meter / 4,9 ft
As the Beemster lake had a total depth of 4,5 meter, rows of 3 windmills each were placed around the lake.
(Row of 3 windmills)
The first windmill of the row would pump the waters 1,5 meters up into a moat. Now the water level had sunk by 1,5 meter. A second windmill was placed by the lowered water board. The second windmill would pump the waters up, again 1,5 meter higher, to the first windmill. Now the water level had sunk 3 meters. A third windmill was placed by the new water board. The third windmill would pump the remaning 1,5 meters of waters out of the lake, to the second windmill. From there, the waters were pumped to the first windmill and from there into the external canal. Eventually the water would stream into the sea.
By applying this ingenious technique, the 17th century Dutch reclaimed the Beemster lake and other large lakes in the West of Holland.
(An old map of Western Holland next to a new one)
As the famous saying goes: God created the earth, but the Dutch created Holland.