Welcome to the chalkmill d’Admiraal

In the town district “Amsterdam North-Buiksloot” along the “Noord Hollands Kanaal”, there is a unique national monument : the last remaining wind powered trass- and chalkmill in the world.
The official name of this  stagemill is “d’Admiraal” , unofficially the mill is known as the “chalkmill” or the “chalkmill d’Admiraal”, referring to the major product the mill produced.  This mill was especially built for grinding stone of various kinds such as chalk and also trass, a vulcanic stone that was delved in the “Eiffel”. Trass being an important bricklaying product.

Come and get acquainted with this superb example of the Dutch industrial heritage. Since 1792 this mill has been very important in the history of Amsterdam-North across the harbour “ het IJ”.
The present miller and the board of the non-profit foundation do everything in their power to promote this working monument. It is possible to visit the mill on special “mill days” on which the mill is open to the public. One can also contact the miller for an individual- or a guided tour for groups or consult the miller

The history of the mill
Elisabeth Admiraal, born in 1702, widow of Roelof de Leeuw, ex alderman and mayor of Monnickendam, invested in the mill. She was already in her ninetees when she purchased the “Jan Betten” fen in the “Buiksloter” polder for the sum of 350 guilders in June 1792, the fen measuring “one deimpt and two and a half rod” (over half a hectare). In the same year the mill was built by the millwright Simon Krol and deployed by the end of the year.

At the end of 1793 Elisabeth Admiraal died  and was buried alongside her husband in the choir of the “Great Church” of Monnickendam. The heirs to Elisabeth sold the “shell sand” mill and accompaning land to Jan Spaans in Buiksloot in 1806 for the sum of 3500 guilders. Jan Spaans died six years later (1812) at the age of 52 and a son from his wives first marriage, Timon Grool, became the new owner of the mill. Timon Grool sold the property to his son Simon on November the 12th 1842 for the sum of 4000 guilders. In 1877 Karel Hendrik Ditmar became the owner of the “Admiraal” as did Willem Johan Melchers in 1888.

He deceased in September 1896 and his son inherited the mill. Daniel Melchers installed an (heavy) oil engine and later on an electricity powered engine, not to be totally dependant on wind power.

Apart from selling chalk to painters and trass to masons for mortar, Danial Melchers also sold “Brussels Earth” to iron and copper foundries. He traded asbestos- and pumice cement sheets and also China-clay to potteries.

The raw materials, which were stored in sheds, were supplied by ship over the “Noord-Hollands Canal”. Fine sand was delved nearby “Groet” , a village near the coast in the province of “Noord-Holland” , cray in the north of France and trass in the Eiffel in Germany. Before 1920 the grinded products were transported by rowing boats, gondolas as they were called, to customers in Amsterdam. After that year the boats were replaced by lorries.

Daniel Melchers, at the age of 87, having no successor, closed down his business in 1954. The following year Daniel Melchers died and his heirs sold the mill for the sum of 80.000 guilders in January 1956. The new owner of the mill was the neighbouring “Sand and Gravel trading company formerly D. van Baarsen”, who used the mill as a storing space. Through lack of maintenance the millwork deteriorated. The mill opened up to rain and wind and in the end the sails and wicks had to be removed because of danger of collapsing. Over time the mill and the sheds were reduced to ruins.

In the sixties a group of people decided the downfall of the mill had to be stopped.

The drying barn
The lumps of stone to be grinded are first of all dryed in a so called drying- or wind barn. In former days a number of these large barns stood next to the mill, but at the time of the restorarion in 1967 these had been pulled down because of the delapidated state they were in. In December 2007, a barn was built on the north side of the mill which is partly used as windbarn. The drying-proces can vary from a few weeks in the summer to a couple of months in the winterperiod.

The capstan wheel
As with all the wind-powered Dutch mills, before the grinding comes into operation, the cap construction with the sailcross has to be faced on the wind by the miller to make optimal use of the wind. This so called “winding” is done with the help of the tail at the back of the millcap. By means of ropes and hooks which can be shifted on the reefing gallery, the miller can turn the cap with tail and sailcross 360 degrees by turning the capstan wheel.
Setting of the sails and reefing
Depending on the windforce at that instant, the miller can catch extra wind by setting sail. He can also vary the amount of sail on the sails . The less wind, the more clothe the miller shall set. Reducing of the sail because of strengthening of the wind is called “reefing”.
The milling can commence by lifting the brake on top of the “headwheel”. This is done by pulling the rope hanging down from the “brakestick: sticking out at the back of the cap.

The Headwheel, the Wallowwheel and the Kingsspindle
The rotation of the sails of a mill starts off the interior mechanism. The “sailcross” is secured to the “windshaft” on which the “headwheel” is fitted. The rotation of the sails is transmitted to the “windshaft” and the “headwheel”in the cap. The “headwheel”grabs into a smaller wheel, the “upper wallowwheel”, which is fastened to the upright mainshaft, the “kingsspindle “, running down the interior of the mill. At the other end of the “kingsspindle” the “underwallowwheel” is secured, which grabs into a larger wheel the “stonewheel” . This wheel is found on the “gallery floor”of the stagemill and propels two large upright stones, the “rollercrusher”, on the groundfloor.

The Headwheel, the Wallowwheel and the Kingsspindle
The most impressive part of the mill is the grinding mechanism, the “rollercrusher “. The vertical “rollercrusher” consists of two blue granite stones, an inner and an outer stone, each weighing two and a half thousand kilograms. Both stones roll over a horizontal millingstone, the “bed- or understone”. A walled-up elevation on which the “bedstone” rests is called the “deathbed”. The two stones of the “rollercrusher” are encased in a heavy wooden casement, the “stone window”. Seen from above the upright stones roll clockwise. The crusherstones have some room in the bearings to be able to absorb irregularities. A pair of bent wooden collecting bars, just above the bedstone, ensure that the grinded product is slided back under the crushers.

The Jacobsladder and the boulter
When the stone has been grinded to powder, the miller opens a trapdoor. The stonepowder is caught in the buckets of the “jacobsladder” behind the trapdoor and transported to the “boulter”. The “jacobsladder” is a canvasbelt with buckets at equal distance of one another, running through a wooden pipe with the boulter at the end. The revolving boulter sifts the stonepowder. The sifted “fine sand” is caught in sacks, ready for transport. The coarse particles left behind in the boulter are feeded back to the rollercrusher for a second crushing.

Restoration
After a committee of restoration was established by Mr T.C.Groot in 1964 (later on converted into the present day non-profit foundation), the preparations of preservation of the mill could be set in motion. From the fact that the chalkmill was not mentioned in the book on mills, published by the provence “Noord-Holland” in 1964, one can conclude that the mill was actually abandoned.
The chalkmill was granted to the non-pofit foundation by the “Sand- and Gravel Trading Companyformerly D.van Baarsen” on March the 30th 1965. The foundation had the intention to reinstate the mill in full glory for the grinding of misformed fireclay bricks, obtained from the brickworks. These bricks were to be grinded to powder which was to be used as basis for new bricks.

Restoration costs
The funding of the restoration was largely obtained through contributions made by the state, the province “Noord-Holland” and the city of Amsterdam. The contributions did however not completely cover the estimated costs of 212.617 guilders. Therefore organisations, such as the “Union of Businesses Amsterdam-Noord” stepped in and individuals also contributed. A large sum was acquired by means of the sale of specially made buttons which could be bought for one guilder in all the offices of the Savingsbank “City of Amsterdam”. The non-profit foundation made good use of the button craze which at that time was very popular with the youth in the Netherlands.

The restoration started in October 1965 and did not pass off without problems. At first one thought the foundation of the mill to be in a good enough state, yet later on that appeared not to be the case. The millbody was lifted from its foundation and put down dozens of meters further on by a floating derrick. The millwright J.C.Jonker from “Zaandijk” was able to commence the repair of the foundation and the renewing of the base of the shed and the square substructure under the reefing galery of this stagemill. This structure has been carried out in red iron wood, which has also been used for the new tailconstruction and components of the millcap. Other parts, such as the eight-sided hull, the “kingspindle”( the main shaft) and various cogs did not have to be replaced due to conservation  by the chalk-and trassdust. On May the 30th 1967 the millbody was put back on its original setting and the cap with its castiron uppershaft (dating from 1876) was lifted on top of the hull of the mill. The iron rods of the millwicks were also renewed.

D’Admiraal reopend
On Saturday, November the 4th, 1967, the  Mayor of Amsterdam, Dr.I.Samkalden, put d’Admiraal back into service by lifting the brake. One assumed at that time that the chalkmill  could be fully deployed again. One expected that the yield would cover the exploitation- and service costs and that even a small profit could be made. Despite various efforts it appeared not possible to exploit the mill on a commercial basis.