The types of windmills

Anyone reading, speaking, or writing about windmills is almost sure to think of the famous story of the Knight of the Rueful Countenance, Don Quixote de la Mancha, on his Rozinante. The sedate country squire who, having lost his head after reading a great many romances of chivalry, proclaims himself a knight errant and induces a poor peasant, Sancho Panza, to leave his wife and children and, seated on a donkey, accompany the knight as his shield-bearer on his odd expeditions.

They set out together and in the plain find a large number of windmills, which our knight takes for uncouth giants and accordingly has to fight. Lance in rest, he rushes at them, with the consequence that the turning sails cause him and his jade to roll over the plain. These mills had a cylindrical stone body, covered with a conical roof; they had four wooden stocks with frames on both sides.

The windmills of the type still to be found to-day in the regions of the Mediterranean, with five, six, or more primitive sails consisting of bars rigged with jib sails, in comparison with the Dutch windmills are also only humble wind machines.

But we will confine ourselves to the Dutch windmills, which are characteristic of the country and whose perfection and gracefulness are not surpassed by any other type, in any part of the world.

During our excursions through Holland, by train, by car, by bicycle, on foot, or - better still - in a wherry or a sailing-boat (for Holland is still most beautiful of all when seen from the water!), we shall see windmills, and in some places even very many of them together. They still exist indeed. It is true that they are no longer as numerous as they used to be, but close on one thousand of them are left. That the mills are still there is largely due to those who about 1920 took the initiative in fighting against the neglect of the windmills and the rage for demolition which assailed them from every side at that time. Owners who did not replace their windmills by mechanical pumping stations were considered old-fashioned, those who spoke in favour of windmills were called idealists not amenable to reason; neither the importance nor the value of the windmills in their technical, cultural, or artistic aspects were recognized any longer.

In 1926, under the leadership of Dr. P.G. van Tienhoven, a Dutchman of stature, the champions of the preservation of windmills in Holland published a pamphlet by which they opened the eyes of many people and solicited their membership of De Hollandsche Molen (Dutch Windmill Society), set up in 1923.

The efforts of these men made a considerable impression at that time. From every side people gave their sympathy and aid, so that in course of time the society was able to make its influence felt and to enlighten the general public; it developed into an organization which combined all efforts to preserve windmills.

Thanks to these efforts windmills still exist in relatively large numbers and variety, thus confirming the view of foreigners that Holland is the land of windmills.

On your wanderings in Holland you will see these windmills and they will be sure to fascinate you. But your pleasure will be enhanced when you know a little more about them, when you learn to distinguish between the various kinds and types, and when you know some particulars about their function and, in connection with this, about the way they are built and work. We will attempt to give you an outline and propose to discuss first the different types.

Windmills can be classified in several ways, viz. according to their outward appearance, the way they work, and the task they have to perform. These classifications do not coincide, but they do overlap here and there. This has given rise to names which are not always very clear or unambiguous.

According to their outward appearance the following windmills can be distinguished: the post mill (standaardmolen), the hollow post mill (wipmolen), the large Dutch drainage mill (kloeke poldermolen), the smaller types of drainage mill, the tower mill with a stage (stellingmolen), the paltrok, and the cylindrical tower mill without a stage (torenmolen).

Smock and tower mills are called bovenkruiers (lit. upper winders) and are subdivided into binnenkruiers (lit. inside winders), whose caps are turned by a winch inside the cap itself, and buitenkruiers, which have the winch on the end of a tail pole. There are also beltmolens, built in mounds, and windmills whose towers rise straight from ground level; these latter are called grondzeilers (lit. ground-sail mills).

Finally windmills are classified according to the task they perform into drainage mills, corn mills, sawmills, and further a group of industrial mills all of which, with some variations, have more or less similar, factory-like interior equipment and comprise oil mills, fulling mills, paper mills, and the like.

All these classifications are to some extent arbitrary. A corn mill is usually a tower mill with a stage and a tail pole; if it stands on a town wall, it will also be called a walmolen or wall mill.

Again a wipmolen or hollow post mill is sometimes a corn mill, while on the other hand occasionally - though rarely - a drainage mill with a stage is to be found.

A paltrokmolen is always a sawmill, but there are also sawmills which are smock mills, nor is a small wipmolen on the roof of a barn unknown, which acts as a lattenzagertje (small sawmill in which laths are sawn).

All this seems rather confusing, but we will choose the most obvious method, showing the different types of mill as they appear at first sight, so that you may be able to recognize them from afar.

To see a POST MILL you will have to go to North Brabant, Gelderland, Zeeland, or Limburg. Some are still to be found there, but this, the oldest type, is almost extinct. The post mill is a corn mill, and large numbers of them are to be seen in old engravings.

The body of a post mill consists of a large square box, constructed to turn about a heavy wooden pillar - the post. The breast and the tail of the body are narrower than the sides, so that they may catch as little wind as possible,

Arrangement of the drives in a post mill

while still providing sufficient space inside. The body is turned to enable the sails to be set into the eye of the wind with every change of direction.

The post is supported by a system of double quarterbars and heavy crosstrees resting on brick piers.

The mechanism is accommodated inside the body: two wooden gear wheels on the wind shaft drive two vertical spindles and rotate the millstones in their casings. As a rule the machinery is distributed between two floors, with one set of stones on each floor. It is not complicated and its operation is plain from the diagram. Details of the lay-out of a corn mill will be given later on.

Exterior of a post mill tail, breast and side elevation

The body is raised a considerable distance above the ground, for the sails should have a certain length if they are to reach well into the sky and catch sufficient wind. The wind pressure not only drives the sails round, but also exerts a rearward pressure on the sails and thus on the whole body of the mill. This pressure is taken mainly by the post, aided by the tail construction. At the rear of the mill a broad oaken ladder descends from the body to the ground; further there is a heavy tail pole which - being connected to the framework of the floor of the wooden body - extends from there backwards. This tail pole passes between two rungs of the ladder and then curves slightly downward, while its end is firmly fastened to the end of the ladder by means of two upright oaken posts. At the bottom of the ladder the winch or the winding wheel can be operated. This heavily constructed system of ladder and posts form a counterweight for the great weight of the stocks with the sails, so that everything is balanced. When the mill is working, the ladder with the tail structure may rest on the ground and thus help to take the pressure of the wind on the sails and the mill body. The mill body can be reached from the ground along the ladder.

In the simplest construction the supporting system of crosstrees and quarterbars is open; in this case the mill is called an 'open post mill'. If the base is enclosed and thatched, the system of crosstrees and quarterbars is protected from the weather, and a kind of primitive storage place is obtained; the mill is then called a 'post mill with a roundhouse'.

At the rear of the mill body is a balcony with a handrail, reached by the ladder, and here is the door which gives access to the mill body. Over the doorway there is a fair-sized opening with a shutter and at the top of the tail a pent roof or the like, the shape of which differs according to the region in which the mill is situated and which protects the sack hoist from the weather. The 'sack hoist' is the apparatus for hoisting and paying out the filled sacks and consists of a wooden shaft, which can be coupled to the wind shaft inside the mill and projects from the tail at the back. With the aid of this device the sacks can easily be hoisted by wind power.

In the sides of the mill body are a couple of vent-holes, which can be closed by shutters. When the wind starts to blow through a hole, it warns the miller that its direction has changed and that he should turn the mill. The front of the mill body, called the breast, is usually adorned with a 'prick post' and the lower edge is gracefully curved.

These post mills are very curious wooden structures of considerable antiquity.

The relative small space inside the post mill was not sufficient; the storage space was small, and loading and unloading always had to take place in the open. Hence, corn mills evolved in the direction of the larger mills built of brick. At first, use was also made of the round brick powder magazines found in the towns, which had fallen into disuse for the purpose for which they had originally been designed. These were the torenmolens (cylindrical tower mills).

The post mill is the type from which the wip mill (hollow post mill) developed; this is known to us chiefly as a drainage mill. In drainage mills the mechanism, the scoop wheel or the Archimedean screw, is of course always tied down to a fixed place on the ground and accordingly must not turn with the mill. The turning portion of the mill could therefore be smaller and in consequence more manageable. The base on the other hand became larger and developed into suitable living quarters for the miller.

The total number of post mills in Holland is no more than forty; so they should be carefully preserved. Handsome post mills are to be found in North Brabant at Nistelrode and Uden, in Gelderland at Nederasselt and the Doesburg mill near Ede, in Zeeland at Retranchement and at St.Annaland. There is also a good post mill at the Dutch Open Air Museum at Arnhem, but the appeal of such a mill is greatest in its own natural setting, in the midst of the corn fields. In the national park Buurserzand, in the municipality of Haaksbergen, you will find an open post mill in good condition in the midst of beautiful unspoilt scenery; the premises are owned by the Society for the Promotion of Nature reserves. There is yet another mill of this kind at Ter Apel in the Groningen region.

Hollow post mill
The drive from wind shaft to scoop wheel.
The brake wheel has 68 teeth, the wallower 35 staves; the crown wheel has 23 staves; the pit wheel has 95 teeth.
So the wind shaft has to make 2.12 revolutions for each revolution of the scoop wheel.

The WIP MILL is the graceful mill still to be found in great numbers in the polder regions, especially in South Holland and Friesland; wip mills are nearly always drainage mills and only a few wip mills function as corn mills.

All the indications are that the wip mill - the oldest drainage mill - evolved from the post mill. The square revolving upper part of the mill has now become relatively small, the stationary pyramidal base relatively large. The former has to accommodate nothing but the wind shaft, the brake wheel, and the wallower on the top of the upright shaft. The upright shaft in the centre of the mill extends vertically through the hollow post from the top to the bottom, where the weight is taken by a thrust bearing on the underframe. At its lower end the upright shaft carries the crown wheel, which meshes with the teeth of a large gear wheel, called the pit wheel. This pit wheel is fixed to the shaft on which the scoop wheel is mounted. In this way the scoop wheel is driven by the turning sails. The space occupied by the gearing in the base is fairly large, but the remaining space is often used as living accommodation.

Wip mills are generally painted in very bright colours and they provide a characteristic gay note in the polder landscape. The finest are those whose substructure is covered with the beautiful thick reed thatch protecting the dwelling, broken only here and there by a few small openings for the windows and doors. They impress us as a pattern of cosy domesticity, where in winter the inmates are effectively protected from the violence of the weather; they are in perfect keeping with the raw climate of the low countries, with its frequent rains, showers, and snow or hail storms. In summer, with their thin wasp-waists they look like dainty, gay damsels which, brightening up the whole landscape, are a pleasure to behold.

Wipmolen (hollow post mill).
Left: front view; Right: side elevation.

The wip mill, like the post mill, has a tail pole, ladder, and winch. A couple of additional braces consolidate the whole structure.

The lower portion of the wip mill has an entrance door in each of the two sides at right angles to the direction of the scoop wheel. These two outer doors are required in order to provide free access and exit with any position of the plane in which the sails are turning. The door past which the sails sweep is then kept firmly shut, for it would be highly dangerous if someone were to pass through inadvertently.

The wip mill, the first type of mill with which wind power began to be used for keeping the land dry, was developed in the early part of the fifteenth century. The mill was equipped with the familiar Old Dutch water-raising mechanism of simple construction: the SCOOP WHEEL. The scoop wheel may be mounted inside or outside the mill; in the latter case it is often enclosed in a wooden casing. Originally the wip mills were smaller in size and although they were made larger and larger, they have not the same dimensions and capacity as the larger drainage smock and tower mills, the sturdy fellows built later on, when greater experience had been gained and the task of draining the larger lakes and pools was undertaken. It is obvious that the size of the scoop wheel should vary with the length of the sails employed; its size has to be adapted to the capacity of the mill. We cannot therefore fail to be impressed by the considerable knowledge and practical experience which the millwrights of the early days must have possessed, since they were able to construct everything in proportion empirically and without calculations!

It was not until much later that besides the scoop wheel the Archimedean screw came to be used to raise water; it does not seem to have been adopted for use in windmills until about 1634, and in this connection the name of Symon Hulsbos is

The body of the wipmolen.
Left: tail with door and gable; right: breast with vertical prick post

mentioned. An 'invention' in the true sense of the word it can hardly be called, for Archimedes already knew the cochlea and it is natural to assume that it will have been used before - with hand-power - to drain deep pits or for similar jobs, which undoubtedly regularly had to be done during building operations in the watery regions of Holland.

Here again there is a striking analogy with developments in the sphere of shipping. The scoop wheel was the most obvious mechanism for raising water; it was also the most obvious means of propulsion for ships. In the case of windmills the scoop wheel is in a fixed place and the water is moving, in the case of ships it is the other way round: the water remains, as it were, in the same place, but the ship is propelled. In 1805 the first paddle steamer was put in service and it was only in 1836 that screws were used for propulsion and the ship's propeller was 'invented' by the Swede Eriksson. The ship's propeller is after all nothing but a modification of a section of an Archimedean screw and the paddle a modification of the water wheel.

Whilst in the post mill the body is able to turn about a solid pillar because as the mill body moves the mechanism inside turns as well, in the case of a wip mill the top had to be able to turn without interfering with the transmission from the wind shaft to the scoop wheel. To make this possible, instead of the solid wooden shaft a heavy hollow wooden post is made, about which the top can turn; through this post the shaft is passed. Hence the wip mills also used to be called kokermolens (hollow post mills).

The arrangement of the wip mill is fairly simple; by reference to the diagram its working can easily be understood. About midway the wind shaft carries a large gear wheel, the brake wheel, which drives an upper gear wheel on the upright shaft, the wallower. The latter may be constructed as a lantern wheel with staves mounted between two disk-shaped flanges or as a trundle wheel with cogs mounted in one wooden flange. Fitted round the rim of the brake wheel is a large-sized band with brake blocks, which can be clamped on to the wheel by means of the brake lever. When the brake handle is operated, the brake lever moves from its position at rest, so that by its own weight it contracts on the brake blocks, thus producing the braking effect.

The other components of the wip mills are similar to those of the larger drainage mills; we will revert to them later on.

The living accommodation inside a wip mill is not very large and hence a small cottage, the summer house, is often found close to the mill. It is there that the miller and his family live more comfortably in summer. The summer house is low, so as not to interfere with the catching of the wind. The smaller wip mills are not inhabited.

When the need of larger and more powerful windmills began to be felt, the large DUTCH DRAINAGE or POLDER MILL was developed. It is called a bovenkruier (cap winder), but the name is an indication of the variety rather than a name for a particular type.

These large drainage mills were developed in the watery region of North Holland in the second half of the sixteenth century. They evolved logically from the wip mills when the top was made smaller and the mill body proper larger, in consequence of which the mills could generate a much greater power while still remaining manageable. The larger construction also provides more suitable living accommodation. These mills soon ousted the wip mills in the fight against the water.

The cap is turned in the top of the mill on the inside with the aid of a winch with a hand-wheel or a handle.

It is a constantly recurring and fatiguing job for the miller to go upstairs to turn the mill whenever the direction of the wind changes. The further development of these large mills therefore was in the direction of making it possible to turn the cap from below, viz. on the outside by means of a TAIL POLE. Thus arose the familiar large mill of South Holland.

It is curious that in spite of this ease of handling of the buitenkruier or outside winder the unchanged North-Holland type yet has held its own to this day and the type has been preserved as the binnenkruier or inside winder. Outside the province of North Holland this type does not really occur, but several drainage mills in South Holland still show signs that they must once have been inside winders.

Large octagonal drainage mill or polder mill, South Holland type, with internal scoop wheel.
The tower in front elevation, the lower part in section, to show the working of the scoop wheel.

The only type found in South Holland is the outside winder, the familiar large classical drainage mill or octagonal mill.

The space inside the cap of the outside winder can be smaller than is necessary in the North-Holland type and this is clearly visible from the outside. The appearance of the North-Holland mill is more solid and less elegant, but it is very sturdy, powerful, and tall.

The large South-Holland type mill not only has a smaller cap, but also a tapered form, so that it is more elegant, while moreover it has a rakish tail and owing to its gracefully curved lines makes a much more handsome impression; the inside winder always strikes us as rather 'bare' and uncompromising.

A further outward difference to be noted is that the windmill of the North-Holland type has a wooden base which is higher and is covered with overlapping boards which are tarred or painted. The base of the South-Holland windmill is somewhat less high and built of brick. The body of both types is usually thatched.

The two types therefore can be easily distinguished from a distance. Their interior machinery and operation are practically identical.

The base of the large drainage mill is usually built in the form of an octagon. Supported on this octagon is the wooden structure, consisting of heavy timbers, vertical and horizontal, joined together by sturdy diagonal beams and joists of the various floors. A rigid unit is thus formed; this is necessary indeed, for it sometimes has to withstand considerable force.

The beautifully curved hollow lines of the mill body, so satisfying to our aesthetic sense, also have a definite practical reason: the wind from the descending sail in this way meets with less resistance.

Plan of a large octagonal drainage mill

There are also mills made entirely of brick and they are sometimes six- or twelve-sided, and often also perfectly circular. However, it is not surprising that in Holland, with its soft subsoil, thatched mills built of wood were preferred. These are much less heavy than mills built of brick, Besides, in the Dutch climate it was always difficult to keep a tapering brick wall properly watertight.

The materials wood and reed have held the field up to the present day. They are quite appropriate in the Dutch countryside and climate; good oak timber will last for centuries, as witness the oaken staircases and beams in the handsome houses of the old towns. Timbers covered with reed have always furnished structures fully meeting all requirements of insulation, combined with ventilation, long before the days when this had to be deliberately sought in present-day materials. The same can also be seen in Dutch farmhouses; from the aesthetic point of view it is hardly possible to imagine anything more handsome in this respect.

Construction of the mill body

In the cap of the mill, slightly inclined to the horizontal, lies the heavy wind shaft, the front journal turning in the neck bearing, supported on a wooden block, called a pillow block. At the tail the shaft is supported in a combined journal and thrust bearing. Early bearings consisted of a simple hollowed-out piece of freestone, which was lubricated with tallow. At the present time ball journal and thrust bearings are often used.

The front end of the shaft (the poll end) projects from the cap and the stocks pass through it. The wind shaft is a very heavy wooden or iron affair of some four or five tons. To raise it to the top of the mill and locate it in its bearings without the aids and appliances nowadays available is a difficult and even dangerous job, which can only be accomplished successfully by highly experienced and capable skilled millwrights.

For the rest of the mechanism: upright shaft, brake wheels, wallowers, crown wheels, etc., reference may be made to the description of the wip mill. The gear wheels themselves are masterpieces of skilled craftsmanship; they are made of oak from the Balkans and of lignum vitae. Lignum vitae, besides its hardness, has the additional advantage of being to some extent self-lubricating. The gears mesh almost noiselessly and thus with a minimum of friction, having been made for many centuries by the method of trial and error.

It is pertinent here to say a little more about the function of the drainage mill in general and of the water-raising mechanism in particular.

The scoop wheel is a water-wheel and in its function for the 'transport' of water it may be compared with the wheel which, from time immemorial, has played such a big part in all transport by land: the ordinary waggon-wheel. Even outwardly the two resemble each other closely. If the spokes are imagined to have the form of broad plates (the floats), enclosed on both sides between the brick walls, trough-shaped spaces are formed; as the wheel turns each trough fills at the bottom, is moved upwards, and, when arrived at a given level, empties itself automatically. The outlet thus takes place at a higher level than the inlet, and in this way the water is lifted. The lift is naturally limited, since it is conditioned by the radius of the circular scoop wheel. On practical grounds there is a certain maximum size for the scoop wheel and this means that the water is not lifted beyond a difference in level of 4 feet, or at most 5 feet, by a scoop wheel.

How then was it possible to drain pools and lakes which often had a depth of 13 to 17 feet?

First a 'ring dyke' and a 'ring canal' would be constructed round the lake to be drained, and a number of windmills would be built in predetermined places, for the water to be pumped into the ring canal. When the work had progressed to the point where the level of the water was too low for the scoop wheel to reach it, it became necessary to build a second set of mills, which would start to drain the deeper part of the lake at a level some 5 feet lower. These mills would pump the water into a kind of intermediate storage basin or network of canals, from which the first mills pumped it into the ring canal again. Similarly a third and even a fourth 'stage' could be made if necessary, and thus the deepest pools could be drained. Each set of mills operating in series is called a molengang, a 'gang' of mills, and one or more of these have to be made, the number being dependent upon the size of the polder to be drained. There may thus be cases where pumping in stages comprises only three mills, which pump out the

Lifting in stages.
(three mills in series)

water one after the other; if the polder is not only deep but also covers a large area, more than one series of mills will be required. The mills pass on the water, as it were, from one to the other, and the last discharges it into the ring canal.

The water storage space required between the mills of different stages is formed by an intermediate storage basin; frequently a simple canal is used for this purpose.

The water that is continually pumped into the ring canal has to be removed and it is either drained off into one of the large rivers which carries it to the sea or direct into the sea. The number of discharge possibilities for a large area, however, is limited through natural conditions; in the old days the only possibility of getting rid of the superfluous water was the natural fall, i.e. at the times of sufficiently low level of the sea or river water. It was thus necessary for the water removed from the polders to be stored in a big reservoir until it could be drained off into the sea. Such a reservoir is called a boezem (storage basin) and it is formed by a complex of canals and lakes, of which the above-mentioned ring canal therefore forms part. It may temporarily hold a lot of water, and this is especially important in periods of great rains. Such a storage basin may cover a very large area in one or more provinces and it forms a separate unit. A waterschap (drainage district) has a board of its own; there are also Heemraadschappen (Drainage Boards) and Hoogheemraadschappen (River Boards).

Later, the construction of powerful mechanical pumping stations made possible a better control of the discharge of the water in the storage basin, so that this was no longer dependent on the caprice of natural conditions. Thus the Hoogheemraadschap Rijnland (the Rhineland River Board) has powerful pumping stations at Gouda, at Katwijk, at Spaarndam, and at Halfweg, by means of which the water is drained off either directly or indirectly into the sea.

While every drainage board is autonomous in its own area and authorized to make its own regulations (polderkeur), it stands to reason that the Hoogheemraadschappen also have their own extensive jurisdiction; they may also lay down rules to which the drainage boards have to conform. From the earliest times the drainage districts in Holland possessed sweeping powers, and this is indeed necessary, for the lives of the inhabitants, living many feet below sea-level, depend upon them!

All these drainage districts form peculiar autonomous areas with great influence in Holland. They have left their mark on the whole economy and the administration of the Netherlands as a land of polders, according to the ancient maxim: 'wien 't water deert, die 't water keert' (who is hindered by the water shall stem it). The specific character of the Dutch rural population, the landholders proper, and also of the Dutch people in general, their attachment to property and individuality, all this is closely connected with it.

Reverting to the scoop wheel of the drainage mill, we may observe that it is mounted inside in some cases and outside in others.

The water is fed from the polder by a large polder ditch, along which it is conducted near the mill to the scoop wheel between two brick-lined water walls. The scoop wheel fits accurately between the two water walls, pumps up the water via the water guide, and discharges it between the water walls to the ditch, mill race, ring canal, or whatever the name of the water may be. At the mill, the feed side of the water is called the intake, the discharge side the tail race. To prevent the water flowing back from the tail race to the intake during the periods when the mill is not working, the tail race is shut off immediately behind the scoop wheel by an automatic sluice door, which, in the same way as a lock gate, is closed automatically by the pressure of the water. As soon as the scoop wheel starts working, the dammed-up water automatically opens the door, so that it can flow off to the tail race. It is obvious that some over-pressure is required to open the door; this accounts for the fact that the mill does not displace water with the slightest movement, but has to reach a given minimum speed to keep the door open, although very little water, if any, is then displaced; the displacement does not start until the speed of the sails begins to increase.

The WATER SCREW (i.e. an Archimedean screw which is partly enclosed in a casing and is adapted to raise water) was used in drainage mills only from 1634 onwards. If such a screw is made long enough, it is possible to pump up water with it from a depth of 13 to 17 feet. This means a considerable simplification as compared with a series of three mills one behind the other. For deep polders and reclamation projects therefore Archimedean screws would often be employed.

One of the results of the competition held by the Dutch Windmill Society was the suggestion of the millwright A. J. Dekker to use centrifugal pumps in a drainage mill where the lift required is not very high. This was not a success after all; these pumps may sometimes involve too heavy a loading on the windmill. We have already pointed out before that the water-raising mechanism, the size and capacity of the mill, and the tensile strength of the parts, all have to be adapted very accurately to each other if unexpected unpleasant consequences are to be avoided; in the old windmills this relationship, well-tried through the years, is always present.

Arrangement showing method of driving the
Archimedean screw, of a drainage mill (after Krook)

The Archimedean screw is inclined downwards into the polder water; it turns in a brick-lined casing enclosing approximately one half of the screw, but open at the top. When it has reached the top of the screw, the water flows over a low sill to the tail race. A sluice door or trap, which is closed by its own weight as soon as the screw stops, prevents the water in the storage basin flowing back to the polder.

In the provinces of North Holland, Friesland, and Groningen many screw mills are found and few mills with a scoop wheel. In South Holland it is just the other way round: the scoop wheel has held its own there.

To prevent floating fragments of wood, tangles of waterplants, or accumulations of duck-weed from interfering with the operation of the scoop wheel or screw, on the intake side near the mill, i.e. on the polder side, there is a gate, which with its bars holds back any undesirable objects. It is the task of the miller to clean this gate regularly by removing the dirt; this is done from a plankbridge which has been built across the water intake along the upper part of the gate.

At its further end the scoop-wheel shaft carries a large gear wheel driven by the crown wheel on the upright shaft; this is the PIT WHEEL. It turns partly above ground level and partly in a bricklined culvert sunk into the ground. When the scoop wheel is built inside the mill, all these components, along with the upright shaft, occupy a considerable area on the ground floor of the mill, approximately one half of it. Next to this is the passage, and the other half of the ground-floor space is taken up by the living-room with built-in beds. Next to this, on one side are stairs leading to the first floor with the other sleeping-quarters and thence to the other floors; on the other side is a small ladder leading to the cellar.

Below is the storage space for fishing-tackle and the like, at least if this space is not occupied by the culvert in which the pit wheel turns and by the scoop wheel itself.

Owing to the shape of the mill and the way in which all the living quarters are fitted in, these rooms have very peculiar dimensions and make for a cosy, though somewhat primitive, interior. The living-room has fairly large windows, divided into small panes; on the upper floors small windows are let into the thatch. No fuss is made about the way in which the smoke from the hearth in the living-room is to be carried off: the chimney is extended some distance upwards inside the mill and discharges into one of the upper floors, whence the smoke has to make its way out as best it can through the chinks in the cap! Incidentally this has a great advantage: the woodwork is preserved marvellously well by it!

The genuine large octagonal polder mill of South Holland, with its brick base and thatched body, is the finest type of all.

Anyone interested in windmills should go and have a look at the magnificent group on the Kinderdijk. Sixteen large drainage mills are there grouped close together, a really fantastic spectacle. This mill complex of the Overwaard and the Nederwaard near Alblasserdam is of the greatest importance from the point of view of scenery as well as for historical reasons.

But other, smaller, complexes of windmills presenting a magnificent sight are also to be found in the heart of South Holland. When following the motorway from Gouda to The Hague, one will see on the left the four mills belonging to the Tweemanspolder under Zevenhuizen, a gang of four mills which make a fine spectacle as seen from the road and which are still in good condition, although they are no longer regularly in working order. Another complex, near Leidschendam, to be seen from the motorway from Ypenburg to Schiphol, consists of the three handsome mills of the Driemanspolder, which again are not in regular working order.

Anyone who wants to see a wonderful set of windmills still in working order should visit the gang of four mills of the Drooggemaakte Polder aan de Westzijde van Aarlanderveen (a drained polder to the West of Aarlanderveen); these windmills, situated in the municipality of Alphen aan den Rijn, are easily accessible from the road leading from the Aar canal eastward to the village of Aarlanderveen. They are each of them splendid mills, with their own picturesque setting and grouped together in an unique meadow landscape.

Besides the large polder mills (which pump some 1,750 to 2,000 cubic feet of water per minute) and the wip mills, of which there are larger and smaller specimens, there is yet another type, a kind of small wip mill, known by the name of SPINNEKOP (spider), a mill whose capacity is relatively small and which is equipped with an open Archimedean screw. The construction and equipment of this mill are wholly similar to the ordinary wip mill. The 'spiders' are mainly found in Friesland and the stationary base is there covered with rooftiles. The miller has to visit them regularly to control them, often from a considerable distance. The span of the 'spider' is rarely more than 30 to 40 feet.

It may sometimes happen that a few plots of land in a polder for some reason or another require additional pumping. In such a case a much smaller mill suffices and a WEIDEMOLENTJE (meadow mill) or AANBRENGERTJE is used. This need not pump the water into the ring canal, but discharges it into one of the polder ditches of the surrounding land. It is an even smaller specimen of the wip-mill type and it requires little attention, if any. These small windmills came into use in the course of the nineteenth century and at the present day there are still fair numbers of them in the province of North Holland.

At the back of the movable top there is a large, flat wind vane. Thus the mill will automatically face the wind and is always kept into the eye of the wind. The stationary base is an enclosed empty space; including the cap, the height of this mill above ground level generally does not exceed 10 to 13 feet and the span of the sails is in accordance with this. The water-raising mechanism consists of a simple centrifugal pump, usually three- or four-bladed, made of wood, which raises the water vertically.

Small meadow mill

Latterly instead of these small windmills the ugly iron aeromotors with a pump were used. Still, in the long run they were found to involve some disadvantages, so that after World War II the wooden windmills came into their own again. In order to keep the cost low, they are now made to a more modern design, although the old characteristic shape has been retained. The base is of concrete and thus requires no maintenance at all. Mounted on this concrete base is the pyramidal body, made of wood, with on the top a winding gear running on ball bearings. The sails have only boards and no sail-cloths.

The revolving top therefore is very easily turned to face the wind; this is brought about by the familiar large wind vane at the back, and the whole mechanism runs very smoothly. The construction of the wind vane in these modem windmills has the additional feature of a gale-safe device: in stormy weather the vane flaps aside altogether against spring action, and thus moves the sails out of the wind. The mill then stops and cannot be damaged by the gale. When the gale is over, the vane has to be readjusted to its original position by hand. For the rest this mill does not require the slightest supervision; the whole mechanism runs so smoothly that the sails need no cloths; the wind shaft as well as the upright shaft turn on anti-friction bearings. The rare occasions on which some one has to go up to the mill to readjust the vane provide sufficient opportunity to check whether everything is still in good order.

Finally there is still a small windmill of the simplest construction conceivable: the TJASKER.

The simplest drainage mill: the Frisian tjasker

This is found almost exclusively in the province of Friesland, and even there only very few specimens exist.

Properly speaking, it merely consists of a continuous inclined shaft, the upper end of which carries a set of sails, while the lower part ends in a closed Archimedean screw. A casing is thus not even required. The bottom of the screw is immersed in a deep pond, which communicates with the polder water via a culvert. The stocks have a length of 17 to 20 feet; they carry the common sails with leading boards and cloths. On the shaft a brake is present.

The legs of the trestle rest on a circular wooden beam, which sometimes lies loosely on a ring of concrete fitted round the pond; in this way the trestle can be turned round on this ring, the pole in the centre of the pond acting as pivot. The turning of the tjasker is a rather heavy and cumbersome job; as a matter of fact, the whole thing is extremely primitive. It is therefore not surprising that these mills have fallen entirely into disuse. But they are very curious indeed.

The STELLINGMOLEN or tower mill with a stage can easily be recognized from a distance; it towers above other buildings, the hideous tower flats of recent years excepted!

Owing to the need of additional working and storage space, about 1604 Dutch millwrights started to build large and tall mills; these were able to catch the wind across other buildings and did not have to be erected on the outskirts of the towns, where the walmolens or wall mills used to be placed. In villages, too, the tall windmill was useful, for there it was the trees which, in addition to the houses, tended to interfere with the free wind, while the large space inside the mill was also quite welcome there.

In the polders and the flat fields there is no difficulty in catching the wind and the drainage mills therefore are not very tall; they can be operated from ground level, they are grondzeilers (ground-sail mills). With tall windmills the cap is sometimes at a height of more than 100 feet and a special provision has to be made to enable the miller to get at the sails so as to set or reef the cloths, to turn the capstan wheel of the tail pole, or to operate the brake rope. This provision consists of a CIRCULAR STAGE with a HAND-RAIL, which is built round the mill tower halfway up.

The stellingmolens are familiar to us as industrial mills and corn mills. It is only rarely - as at Haastrecht - that a tower mill with a stage is used as a drainage mill. On the other hand there are corn mills built as grondzeilers, where wind conditions are such that a tall mill is not necessary.

The stage dominates the outward appearance of the mill entirely, and that is why it is often called a STAGE MILL. They are huge structures; their height is properly appreciated when they are seen in the midst of the town houses, as at Schiedam, for instance.

The tall construction is eminently suited for corn-milling; there are as many as six or seven floors and each floor can be used for a separate part of the process. The grain is hoisted up in sacks to the bin floor; this is done quite simply by means of the sack hoist, which is driven by the wind power. The grain then flows by gravity from the hoppers to the stones on the stone floor, where it is ground. The meal flows to a lower floor, the meal floor, where it is collected in sacks. Below the meal floor are the grain floor and the grain store.

The stone floor or the meal floor, or a combination of the two, as a rule is to be found at the level of the stage; the latter can only be reached from the inside.

Above the bin floor is the dust floor, and above this the top floor in the cap. On the dust floor there is sometimes an awful mess: dripping oil, dust, smoke from the chimneys whirling round there before escaping through openings and chinks, so that the miller enters this part of the mill only when necessary.

In the lower part of the mill the first - and sometimes the second - floor form the living quarters for the miller and his family; this accommodation is very spacious and comfortable when we compare it with that of a drainage mill.

The tower mill with a stage, the corn mill that is often seen
in old towns, generally on the town walls (wall mill) (after Krook)

The diameter of the tower mill, which is always round and made of brick, at the foot is about 30 feet. Several rooms and cabins are present, all of which - owing to the round shape of the mill - have windows giving out on the surrounding scenery; thus they form a very pleasant interior. On the ground floor are the big stable doors, two pairs facing each other, for the horse and cart, which brings the grain or takes the meal to the customers, to enter and leave the mill.

As already said, the loading and unloading of the sacks takes place with the aid of the sack hoist in the top of the mill. Square holes are cut in each floor, vertically above each other, through which the sacks are hoisted. Each hole is closed with a double-flap trap-door having a hole in the centre, for the hoisting rope to pass through. When the sacks are hoisted, they themselves push up the two flaps; when the sack has passed through, the flaps close automatically again, thus closing the opening.

The interior of an industrial windmill

The tail pole ends at the stage. It is there that the cap is turned, and instead of the anchor posts, which for other mills are planted in the ground, the anchor chain is hitched to the beams of the stage with the aid of a couple of hooks.

The BERGMOLEN or BELTMOLEN (mill built in a mound) is found in the higher regions of the Netherlands; it is a halfway house between the tower mill and the grondzeiler (ground-sail mill).

The mill itself is not particularly tall, but it stands on, or rather: in, an - artificial - mound. The base up to the first floor is built entirely into it, and the surrounding ground thus has the same function as the stage in tall mills.

Parts of the mound are dug away to give access to the large loading doors in the base, through which the horse and cart can enter, and leave the mill on the opposite side.

The interior arrangement of the bergmolen does not differ from that of corn mills in general, and this will be discussed separately below.

The PALTROKMOLEN was developed in the Zaan district, the area where wooden houses and ships were being built, where timber arrived from various parts of the world, and where sawmill yards and the timber trade were established.

Timber, which often arrives in the form of rafts, has to remain in the water for a long time before it is sawn. On this account sawmills are always situated along a water-front, and sometimes they are completely surrounded by the water, in which the logs float.

The logs and beams have to be sawn in the longitudinal direction and for this purpose they are passed through saw frames, i.e. frames in which the saw blades are tensioned and which are moved vertically up and down by the working mill.

Owing to their length the logs project considerably on either side of the mill. For this reason on both sides of the mill body some sort of roof or penthouse is provided, closed in front and open at the back. As the mill is always turned to face the wind, these wings protect the workers from the weather. They are part of the working-space, form an integral unit with the mill, and give it the characteristic appearance to which this sawmill owes its curious name and to which we have referred above.

The paltrok sawmill, front elevation (after Boorsma and Visser)

The mill itself also is entirely open at the back; it has a stage over part of its circumference and on this stage the miller can pass from one wing to the other. The floors of the wings form a continuation of the working floor in the mill and the whole is called the sawing floor, for here, in the centre of the mill, are the saw frames and on the floor are the carriers on which the beams and logs to be sawn are lashed up to be fed through the saws.

The way in which this sawing takes place will be shown later on, when the interior of the sawmills is discussed. In the ordinary windmills the brake lever as a rule projects at the back and it is there that the mill can be stopped; in sawmills the brake rope ends on the sawing floor, ready to hand, for sometimes the mill has to be stopped suddenly, when the saw makes a loud scratching noise on a nail or some other foreign object.

The mill with the wings is built entirely of wood; the cross- section of the body is rectangular rather than square, since the sides are slightly longer than the front is wide. It must be possible to turn it as a whole, along with the wings, to face the wind. It might thus be properly called a 'lower winder' - and it is the only mill of which this could be said - but this name is hardly used.

The paltrok sawmill, rear elevation
(after Boorsma and Visser)

The paltrok is supported on a circular brick wall with an oaken sill, called the winding floor. Moving on top of it are rollers, enclosed in the curb and covered by a wooden floor. The curb is connected in several places by means of radial spokes with the centre of rotation. This centre of rotation is formed by a KING POST, which rests on the heavy central pier of brickwork. Constructed round it and adapted to rotate on a heavy pin is the framework of beams on which the mill is erected, and also the heavy tail pole. This tail pole passes underneath the mill towards the back, where it projects about 10 to 13 feet beyond the curb.

The curb indeed takes part of the total weight of mill and wings, but it mainly acts as a guide during the turning. The major part of the weight is taken by the king post.

Inside the mill are several floors; from bottom to top there are the sawing floor, the frame floor, the 'empty' floor, the crank floor (where the crankshaft is to be found), and above this the top floor.

To feed the logs conveniently from the water to the sawing floor, which is some 7 feet above the water, use is made of a swivelling wooden crane mounted on one side at the end of the sawing floor. The crane rope passes towards the inside and is wound round a wooden roller, which can also be turned with a ratchet wheel mechanism through the mill gearing. Thus the log can be hoisted up by wind power, turned above the floor, and then lowered on to the carriers.

The paltrok sawmill, side elevation
(after Boorsma and Visser)

The first known sawmill was the mill called Het Juffertje (the Damsel), invented by Cornelis Cornelisz of Uitgeest; he obtained a patent on it in 1592 from the States of Holland.

In 1596 Het Juffertje was moved by water on a heavy wooden raft to Zaandam, where several improvements were made and a larger number of saws was installed in it; in this connection the name of Dirk Sybrandts is mentioned.

It was from this first sawmill that the paltrok developed about 1600, followed by sawmills of the smock-mill type. In general the span of such a smock mill is somewhat larger than that of a paltrok. Mills of this type therefore were able to saw slightly heavier logs or to work with a few more saw frames. As a rule the paltrok mills were used to saw wainscot, i.e. the oak timber that is sawn from a log which has first been cleft in two over its full length. It is then possible to saw in the direction of the medullary rays and thus to obtain the boards showing a richly grained surface, which is highly valued for the making of handsome furniture and panelling.

The body of a SAWMILL OF THE SMOCK-MILL TYPE is not erected as the customary octagon, for then there would be four upright posts in the working-space, near the carriers; a hexagon or a square is chosen. Built immediately against the mill are a couple of fixed, low sheds, extending beyond the wings forming part of a paltrok. Such a shed does not include a crane, but ends with a slipway in the water, so that the beams and logs can be dragged along it by wind power from the water and towards the saws.

The internal brake rope and other equipment are similar to those of the paltrok and will be referred to later on.

An attractive specimen of the smock-mill type can be seen as you travel from The Hague to Amsterdam; it is de Herder (the Shepherd), just to the north of Leiden on the Haarlemmertrekvaart.

Finally a few smaller sawmills exist: small smock mills and wip mills (with a stage). They were used for lighter work and in later years were sometimes equipped with circular saws.

The smallest sawmill is the lattenzagertje, a wip mill on the roof of a shed, where double laths and single laths are made.

Sawmill - smock-mill type - with sawing floor and timber stores
(front and side elevations)

Besides the sawmills there are also industrial mills of several other kinds, but to outward appearance all these mills, called after the product they delivered, belong to one of the types discussed above.

Paper mills included sheds which were exceptionally long (for the paper to be dried in), while there were oil mills with stores along the water-front and a hoisting crane for loading and unloading the barrels, but you will not be able to recognize their function from a distance; nor is it possible to tell whether the small wip mill on the roof of a shed was a pepper mill, a dye mill, or a mustard mill.

The only difference between all these industrial mills consists in the interior equipment.

The corn mills and mustard mills operated with stones rotating horizontally. In the oil and trass mills on the other hand the stones rolled on their edges in a kollergang or circular trough; the same applied to the cement mills, the shell-sand, white-lead, chalk, dye, starching-blue, cocoa, tan, and spice mills.

Oil mills and snuff mills work with stamps, in addition to the set of stones also required. But all these mills as to their appearance can be traced back to one of the types discussed above.

Wherever there were many windmills close together, such as in the Zaan district, practically every mill had its own name; in this way people knew exactly which mill was being spoken of. Besides, isolated mills too had often been given a name of their own. This stresses plainly the fact that a mill used to be looked upon as an individual, just like a ship.

Curious names are sometimes met with, names connected with certain peculiar circumstances, with the history of the mill or of one of its owners; the memory of this is thus kept alive for later generations. In many windmills one can find a foundation stone or a stone in the facade with an appropriate epigram or rhyme, which before he enters tells the visitor something about a past full of tradition. The millers and their descendants were greatly attached to their mills, which sometimes descended from father to son for many generations.

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