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Technical descriptions of English windmills



Martin Watts’ article on Heath House Mill, Wedmore, in Millnotes No 5, August 1973, includes a diagram of Watchfield and Woolavington mills, Somerset, drawn from a lantern slide of 1907 in the library of the Institute of Archaeology, Oxford.

Excerpts from Martin Watts’ books on Somerset and Wiltshire are quoted by permission of the author.


Tower mill, standing today


M J Watts and A J Coulthard, Windmills Of Somerset And The Men Who Worked Them (1978): Ashton mill was built sometime during the third quarter of the eighteenth century, for it is known to have been standing in 1774 according to an estate map of 1797 by William White, preserved in the Somerset Record Office, but does not appear on Bowen’s map of 1760. It is said to have been built on a mound formerly occupied by a post mill and to have incorporated timbers from this earlier mill, one of which was dated 1736*. This cannot be proved, but the reuse of timbers was common practice and those at present supporting the stone floor, for example, have definitely been used previously. Ashton mill was however altered quite considerably at the turn of the century and has undergone extensive restoration within the past twenty-five years.

 Before being modernised by John Stevens in about 1900 Ashton mill contained some basic machinery of an earlier type than commonly survives in windmills. The sails were broad with cloth each side of the whip, a form which can be seen in illustrations of mediaeval windmills but had generally been superseded by the nineteenth century, and the sail stocks were morticed through the timber windshaft. The windshaft carried a trundle wheel which engaged with a lantern pinion mounted on a quant, the lower end of which engaged with an overdriven runner stone. The single pair of millstones were located probably one floor higher than those in the mill at present. About 1900 machinery was brought from the recently demolished Moorlinch tower mill, and Ashton was extensively refitted. The thatched cap, originally turned internally by a windlass, was re-framed, clad in corrugated iron and the endless chain winding gear from Moorlinch was fitted. A cast-iron poll end was fitted to the windshaft and two of the broad sails were replaced by spring sails, the only pair ever to be fitted to a Somerset mill. These provided a degree of self-regulation, while the common sails gave a little more power; a good working combination. It was at this time that the large bins were built in below the cap, the single pair of stones were moved down one floor and the upright shaft and underdrift gear installed. There is no room for more than a single pair of stones in the tower, and therefore the typical indirect drive designed for two or more pairs of stones is connected to a single pair only. The upright shaft, which consists of two sections connected by a dog clutch, is of pitch pine above and oak below, and carries the cast iron mortice spur wheel from Moorlinch, which drives a single iron mortice stone nut. At the head of the upright shaft can be seen the original wooden wallower, with the newer one close above it.

 A crown wheel provided a secondary take-off for the sack hoist, which also was brought from Moorlinch, and the dressing machinery which has now gone. The pre-1900 dressing machines consisted of one bolter about four feet long and two feet in circumference. The fabric cover was in one piece and drawn on like a glove; great care was taken of the cover and it was taken off and cleaned after every six sacks or so of meal. Some bolter cloths were silk, but Tom Petheram did not think that at Ashton was, but from Mr Stevens’ care and concern “it might well have been”. There was also a little brush machine about two feet long, the first quarter of which was clothed fine wire and the brushes were driven fairly fast. The feed to this machine came direct from the stones through the trough bottom by taking off a hand hold cover. This machine was very satisfactory and preferred by Tom Petheram to the bolter. With this set up and with a favourable wind the output of the mill was from 20-30 sacks per day. After 1900 these dressing machines were replaced with a new bolter, with a woollen cloth, and a new or second-hand wire machine, both apparently sited on the second floor.

 Externally, Ashton mill has a distinctive feature of three iron hoops around the upper part of the tower, which were also fitted around 1900. It has been said that parallel-sided towers are examples of bad design in that the cylinder of masonry is more inclined to distort under the weight of the cap and sails than a battered tower and if the rack on the curb is not truly horizontal or circular the cap would tend to jam. Both John Stevens and Tom Petheram however maintained that Ashton mill always “turned sweetly”, but the iron hoops were fitted during Mr Stevens’ ownership so presumably he was taking no chances. The mill was originally whitewashed internally {and is now}, as were several other Somerset tower mills, and had a number of wooden blocks through the thickness of the masonry wall just below the curb. These, and again they could be seen on other local tower mills, were presumably for levelling and fixing the timber curb too, an easier task than to rubble masonry.

*A beam above the stone floor bears the initials, name and date “Paul M Wilkins, June 2nd 1799”. The Paul Wilkins who worked at Ashton mill would have been ten years old at that time.

Guy Blythman, visit 12th June 2015:

There are four floors: dust, bin, stone and spout/ground floor, with the great spur wheel on the latter. There are two opposite loading doors on the stone floor(1). The mill stands on a slight mound, through which a path has been cut to the entrance door on the ground floor.

 The cap turns on an independent ring of rollers running on top of the laminated timber curb, a feature of Somerset tower mills(2). The curb is of wood, with several layers of packing above it one of which is iron, and dead. I did not count the total number of truck wheels but noted that there were two at the rear and two at the sides, mounted in large wooden shoes. I did not examine the winding gear, which is enclosed within a rearward extension of the cap, but from the diagram displayed in the mill it appears that the drive from the chainwheel was transmitted to the rack via a pair of spur pinions.

 The relatively small clasp-arm brakewheel, with four cants, is stayed at the front to the windshaft, also wood, by diagonal timber struts. The brake lever is of wood and curved. The windshaft is bound with several iron hoops at the neck.

 The sack hoist on the bin floor is in the form of a solid wood pulley and bollard; the former received a chain or rope from a corresponding pulley mounted beneath it on a wooden layshaft on which is a spur pinion meshing with the solid all-wood crownwheel. The latter, and thus the drive to the sack hoist, is positioned just above floor level. The hoist is put in and out of gear by working a long curved lever, suspended on a rod from a wooden plate in the wall, on the dust floor from which chains go but there is also provision for disengaging the mechanism from the crownwheel using an adjustable timber, pivoted in a wooden upright, to which the layshaft is attached. The “new” wallower is all iron, the old one solid wood, iron bound, with the cogs sawn off flush.

 The wooden upright shaft goes right down to the bottom of the mill, and is footed in a beam let into the ground floor. This rests on a pair of timbers at right angles to it, which each support one of the upright posts between whom the bridgetree is mounted. The governor is belt-driven from a drum on the stone spindle below the nut; its own spindle is very long and terminates in the floor with the governor just above the latter. I found the tentering gear, which appeared to be incomplete, difficult to interpret but it appears initially to have been split, the steelyard going to links on each of the timbers supporting the uprights carrying the bridgetree, and then up to the bridgetree itself.

 The scant use of iron in the machinery suggests a preference for re-employment of the wooden shafting and gearing from Moorlinch rather than thorough modernisation. Other timberwork may have come from there too, one of the bridgetree supports displaying an empty mortice.

The great spur wheel is part protected by wooden safety guards on hangers from the ceiling joists. There is a crane on the stone floor, with calipers.

 There was at one time a drive from a portable engine, and although no trace of this may now be seen a photograph survives showing it in use, with a belt going from the engine to the external pulley on the windmill.(3). The pulley is at bin floor level and so presumably the drive was to the crownwheel. The photograph dates from the late nineteenth century but before the refitting, and shows the mill with common sails.

(1) M Watts 12/9/2019

(2) Ibid

(3) On display at the mill

HIGH HAM, Stembridge mill

Tower mill, standing today


Coulthard and Watts: Stembridge mill was built in 1822 on what was part of the Eastfield, enclosed in 1792, and incorporated some gear from the tower mill known as Ham Mill which stood nearby. The tower, of random coursed blue lias stone, is parallel-sided to above the heads of the first floor opposite doorways and then tapers quite steeply to the curb. The thatched gable-shaped cap is now unique in England, although many windmills once had thatched caps, and the mill was winded by an endless chain geared to a worm meshing with a rack on the outside of the curb. The sails have no stocks, the frames being supported by backs bolted to an iron coffin cross fixed into the end of the timber windshaft. The sails were set from a circular earth and masonry mound built up around the base of the tower, and access is obtained to the tower at ground floor level on the lee side through the mound and to the opposite first floor doorways from the mound level. The mill contains four floors and incomplete gear which once drove two pairs of stones. An interesting feature which occurs in several Somerset tower mills is a fireplace, located in the wall of the lowest floor, with a flue running up within the thickness of the tower wall to an outlet just below the cap. The brakewheel is of clasp-arm construction and was probably salvaged from the earlier mill, bearing notches which indicate it was once supported by compass arms, and has morticed wooden cogs. The overdrive to the stones, an upright shaft which carried a spur wheel and the pinions and spindle it drove, is missing but the two pairs of 4ft stones are in place. Those at the front of the tower are French Burr, the runner carrying balance weight pockets patented by Clarke and Dunham in 1859 in its plaster back, and those at the rear are of sandstone conglomerate bedstone and French burr runner stone and were underdriven by bevel gearing from a portable steam engine set up outside the tower. This gear is still in place, and the horizontal shaft from the engine drive also carries a belt pulley which drove the wire machine which is situated behind the meal trough. There were no bins built into the mill and the hoppers and associated timberwork as well as the cases enclosing the stones have gone.   

 The mill carries the names of former millers and workmen, among them F W Lavis, millwright of Long Street, Ernest Fisher, thatcher of Pitney Hill, and J Spearing with the date 1898 written in red oxide on a stone floor beam.

WORLE, Vale Mill

Tower mill


Coulthard and Watts: Vale Mill was a typical Somerset tower mill, a parallel-sided stone tower with a gable-shaped cap, originally thatched but later covered with corrugated iron. The cap was winded from inside, the gear being housed in a tailbox, and the four common sails drove two pairs of stones through spur gearing on a pitch pine upright shaft. The gear was predominantly of timber, even though the mill was of nineteenth-century origin, with a clasp-arm timber brakewheel mounted on the timber windshaft and a clasp-arm timber great spur wheel on the upright shaft which drove the stones from below. Like Ashton mill Vale Mill had a governor driven by belt from the upright shaft below the stones. There were no big bins in the mill, the corn being emptied into the hoppers of the stones in the usual Somerset windmill fashion, and the dressing machinery and sack hoist were driven from a crown wheel on the upright shaft on the second floor.