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Technical descriptions of English windmills



Smock mill, standing today


From Millnotes, published by TIMS 1974:

Denis Sanders: A Cambridgeshire smock mill: West Wratting

West Wratting, Cambs, is an extremely interesting mill, small, cramped and ugly, with a number of curious features.  Indications of change and adaptation can be seen, the significance of which may best be appreciated after prolonged study. However the following incomplete notes are the result of a single visit on 30 April 1960, in company with K G Farries, who took an excellent series of interior and exterior photographs, while I examined the fabric, then retaining the working sails and most of the milling gear.

  {The mill is} a small three-floored octagonal smock on a round brick base, with pepperpot cap and four sails, clockwise viewed from the front; one pair is of patents, one of cloth. {The cap is} hand-winded, with a heavy wooden tailpole and side braces to a wide-span turning beam in the cap. The sheers extend at the rear and carry a vertical wooden slotted guide for the striking lever, with pulley over top; also a chain tie to the tailpole.

 The smock is horizontally boarded on eight sides, but overlaid with vertical boards and cover strips on the four southern (or weather) sides. An engine drive pulley is mounted low over the east door.

  There are eleven bays to the double-shuttered patent sails, and the bars are tenoned into the hemlaths, with a wood pin through the tenon tail, like a cog shank fixing.  Hemlaths present their broad edges to direction of rotation, and bars have barefaced tenons.  The common sails, on the forward stock, do not have this unusual feature.  Pairs of deep timber clamps used on both stocks.

Red brick base, circular and tarred, with slight batter.  About 7 feet (2.13m) high, measured outside, doors on west (now bricked in) and east sides. Former windows on north and south sides, both bricked in.  Internal diameter about 16 feet (4.88m), thickness of brickwork 18 inches (457mm).

  Two pairs of underdriven stones on first floor, on 8 foot 9 inch (2.67mm) centres; both bedstones burrs, with peak runner on west  side, burr on east.  Short wooden bridge trees between pair of main beams set across door lintels.  These beams give 6 foot 3 inch (1.91m) headroom over concrete floor, are 11 and a half inches (292mm) square, on 4 foot (1.22m) centres, and carry between them at mid-point the wooden sprattle of same section.  1 inch (25mm) iron rods on either side of sprattle tie the beams together, and a 6 foot (152mm) square wooden post gives direct central support from ground.  The west governor is between the main beams close to wall, the east one (damaged) in north-east corner. 

  Fixed ends of bridge trees are twin tenoned and carried by short vertical timbers bolted up to inside faces of the 11 and a half inch (292mm) square beams.  Each has an associated bray, of wood, carried parallel and close to the inside faces of the beams, with the neat arrangement of being in the opposite sense.  Thus the west bridge tree is pivoted at north end and its bray fixed on the south beam, while the east is pivoted at south end, with bray on north beam.

  Both brays are pivoted towards mill centre, and the tentering controls, of downturned cowhorn type, are just inside the doors and very dangerous, particularly the east which has a longer bray – 3 ft 9 inch (1.14m) overall, compared to three foot (0.91m) of west – and gives only 5 foot 4 inch (1.63m) headroom.

Both bridge trees have bridging boxes, and both stone nuts are raised out of gear, east by twin rods and ring, west by an all-wood rigger carried by two wood brackets like roller towel fittings.  When in use the control cord was belayed to a large wooden marine-type cleat.

  Stone floor beams are 9 feet (229mm) square, on 6 foot (1.83m) centres, and run east-west, same as the larger ones below, with about 24 inch (610mm) clear vertically between the two pairs.  These beams are most unusually made from two full-section pieces.  Each one has an angled splice joint centred about 18 inches (457mm) east of mill centre, with the splice 21 inches (533mm) long.  On each side of each splice is an iron tie 3 feet (914mm) long, dogged at its ends, and the splices are double-bolted vertically.  This scheme was probably used in order to assemble the beams in position, without disturbance to the structure and boarding, during the reconstruction.

  The beams are mounted between opposing cant posts and carried by a special adaption. The eight smock sills, 7 feet by 5 feet (178mm by 127mm), have been supplemented by eight extra sections 12 inches by 4 and a half inches (305mm X 114mm), fixed flat over them across the corners, butting inside faces of cant posts, and forming footings for eight vertical timbers spiked to these faces.  On the east and west quarters they are about 14 inches high, and 6 and a half inches by 4 inches (165mm X 102mm) thick, and form four short legs across which the stone floor beams stand.  On the north and south quarters the four timbers are about six feet (1.83m) high, 7 feet (178mm) wide and tapering upwards from 4 feet (102mm) to 1 foot (25mm) thick, as strengthening spurs for the posts.

  The bedstones are carried by pairs of bearers between floor beams; runners still in place, exposed because cases, horses and hoppers all gone.  The great spur gear has double clasp arms and wooden rim, with iron segment teeth replacing wooden cogs.  Spur is about 7 feet 6 inches (2.29m) diameter, mounted close over sprattle, and has a slightly bevelled iron gear ring on underside of rim for machine drives. 

  Dresser drive was curious, due to cramped conditions.  An iron wood-cogged nut about 14 feet (356mm) diameter, on an iron shaft, takes the drive off the downturned ring below great spur, on west side.  Inner end of the shaft is carried by a beam pivoted to raise and lower nut in or out of gear.  This beam is between the main pair, inside the west bridge tree, and the nut (with a close-set wood pulley) is right alongside latter, the shaft passing over (or through) bridge tree in a special chase cut to clear it. 

  The shaft carries a second wooden pulley, 18 inches (457mm) diameter, at its outer end, which drove up to a countershaft having two more wooden pulleys, the driven one 14 inches (356mm), the other 24 inches (610mm) higher up, thus giving clearance for the large one to drive right across to the dresser hard against the south side of ground floor. 

  The eight pine cant posts are (out of) 6 and a half (165mm) square, and 17 feet (5.18m) long with two sets of transoms centred about 7 feet (2.13m) and 14 feet over the sills.  Crossed and halved bracing is used in the sixteen main panels, with three lines of vertical studs in each quarter.  The eight small upper panels have a central vertical, and two braces forming a “V”.  The transoms (which play no part in carrying the floors) and crossed braces are pine, 5 and a half inches X 3 inches (140mm X 76mm), all with long sides flat to frame, and all tenoned into cant posts with single pin fixings.  Rent lathing is nailed to exposed inside faces of weatherboarding, as key for plastering in all panels, between the timbers.

  Ex-post mill ladder strings seem to have been used for making the bin floor beams; they are pine, 9 and a half deep by 4 and a half wide (241mm X 114mm), on five feet 2 inch (1.57m) centres, and run   east-west, similar to the lower two pairs.  They are housed into the inside faces of the cant posts, have the tread housings (from their former use) blocked with wood, and the north beam has two heavy iron hooks bolted up on its south face, for use in conjunction with the vertical wooden millstone-raising winch on north side of stone floor.

  The winch consists of a long wooden drum, footed on a braced frame, and carried at the top by a wooden bearing block bolted to a ceiling joist.  Operation was by a detachable hand crank, with iron worm gearing at lower end of drum. A thick rope was used, and the self-locking action of the worm, automatically sustaining the load, must have made this a most useful piece of equipment.

  Since stone and bin floors (first and second) are not based on transoms, the outer ends of their joists (away from the beams) are carried by whatever part of the frame (stud, brace or cant post) comes conveniently on pitch; spiked fillets are also used. 

  Elm segments in two concentric rings, superposed and breaking joint, form the curb, which is about 9 feet (229mm) square, 11 feet (3.35m) diameter overall, and shod with iron on top and inside faces, for cap accommodation.  Iron dogs tie curb down to cant posts inside, and intermediately to centre of each flat, outside.

  The cap frame is of “split-sheers” pattern, where the lateral full-width spindle beam becomes a major structural component, rigidly uniting front and rear sections: as opposed to the type having full length wide-set sheers, with a non-structural spindle beam between them.  Here, the “sheers” consist of three parallel pairs, at varying distances apart, as required; all run fore and aft, one pair behind, and two in front of, the large central spindle beam.  They are disposed as follows:

  Those behind (tail sheers), on about 4 foot 9 inch (1.45m) centres, extend back beyond the cap; they carry the short tail beam, about 18 inches (457mm) forward of the curb.  Ahead of spindle beam, a short wide-set pair, one on either side of the brakewheel, connect with a heavy timber across curb just forward of wheel.  This timber carries the third (close set) pair, which extend forward again to the short weather beam, forming the base of windshaft carriage at head.

  This form of framing (with lack of inherent fore-and-aft stiffness) demands great rigidity of jointing.  Sheer pieces are usually tenoned into cross members, and brought tight with various iron clamps, dogs and tie-rods. “Handrail bolts” are often used to good effect, also; but these details were not checked at West Wratting.

  Ten curved equi-spaced elm spars, sawn out of the solid, rise from a rather light cap circle; all are tenoned and pinned at top into a two-piece horizontal wood disc about 2 feet (609mm) diameter, but the wooden acorn finial formerly footed here is missing.  The cap is covered by upright boarding, banded at base with hoop iron, finally weathered by a deep petticoat of vertical boards with cover strips, lipped behind at junction.  Internally the cap is lathed and plastered.

  To centre the cap, six iron truck wheels are mounted in oak blocks bolted beneath spindle beam and sheers, two at front, two at back, one each side. For turning to wind the dead system is used, with iron skids or slippers secured beneath beams and rollers, to bear direct on iron-faced curb.  However two rollers, below the short weather beam, at front, give some relief at this point of heavy pressure. The main cross winding beam, extending on either side to receive the long tailpole braces, is bolted on forward face of spindle beam.

  The neck bearing for windshaft is on a short thick timber set between a pair of uprights on weather beam, and blocked below also, for extra support. The neck journal is about three feet (0.91m) over curb level, giving very sharp inclination to shaft, about 15 degrees, but distortion of the cap frame may have altered this.  The shaft is iron, circular, 12 feet (305mm) diameter at neck journal, and about 8 feet (203 mm) just behind, tapering to 5 and a half inches (140mm) at tail; two 18 inch (457mm) square flanges about 18 inches (457mm) apart are cast on for wheel mounting, and shaft is 9 feet (2.74m) long behind canister to tail journal. 

  The brakewheel is about 7 feet (2.13m) diameter, of clasp-arm type, with single arms splay-locked at joints to resist wedging thrust; iron segment teeth, arranged as face gear, are of about three and a half inch (89mm) pitch, with 4 foot (102mm) face.  It was formerly a compass-arm wheel, with two intersecting arms (four spokes): this dictated the simple robust pattern of four deep cants giving a large (basically square) opening.  However, a curious decorative feature was added.  In each of the four angles, a corner block was fitted, and then the three members (two cants and a block in each case), were circled out internally, and a delicate moulding formed on rear face. These patterns are not concentric with the wheel but struck from a point nearer the circumference. They terminate at the position of the former compass-arms. The “new” clasp-arm ends cut rudely into the fine work – one wonders whether any regret was felt when making the conversion!  There is a carved date 1726, also I.W., on the wheel.

The elm brake is in segments, 7 and a half inches (191mm) face by 5 inches (127mm) thick, with iron butt-straps.  On left side the wooden lever, tenoned to a stub, is 5 inches by 7 inches (127mm by 178mm) deep (constant throughout), with a natural curve towards centre at rear; an iron catch in a slotted timber is hung from roof. 

  Although of clasp-arm pattern the wallower, about 5 feet (1.52m) diameter, is a hybrid, with only two arms whole; the other two complete the square internally to clasp the shaft, but do not continue out to join rim.  All arms are 12 inches deep; the short ones are set in splayed housings on inside faces of long ones, for wedge thrust, and doubled iron tie rods, right through long pair on each side of the square, bring all tight.  It may be a conversion, and is certainly strong; (the type occurs elsewhere).  Here, the heavy wood rim carries wood cogs, held by wood pins through shanks, driven down from top face.  Flat wood segments are secured below wallower, for a right angle (not bevelled) drive for sack hoist.  The iron-bound wood friction wheel, with bollard, is carried in a wood frame, with cord and lever control. 

  The upright shaft is in two parts; the lower of iron, the upper of wood. There is a dog-clutch coupling at bin floor level, with an intermediate bearing just below. The bearing is mounted on a beam 7 and a half inches square, offset 9 inches east of mill centre, to clear shaft.  This full-width beam runs north-south, is bolted to soffits of bin floor beams, and is carried at its ends by the smock framing.  The iron section of the shaft is 7 inches in diameter, footed in a bridging box on sprattle below.  The wooden upper part was either weak or damaged, it seems, so has been cased on four sides with pine plates about 1 and a half inches thick, though-bolted in both directions. The corners are chamfered to give an octagonal shape overall. The wallower is stayed to this shaft, from below, by four iron members which rise up at about 30 degrees.  The great spur is positioned very low on the iron section of upright shaft, within the box frame formed by the two pairs of parallel beams in the ceiling of ground floor.  This wheel, with the stone and machine drives, is described above.  Both stone nuts are of iron with wooden cogs. 

  The “split sheers” cap frame occurs at a number of mills in this area; large and small versions can be seen at two Soham mills, Downfield tower and Shade smock, where the caps have about 15 feet and 10 feet diameters respectively.  The type is occasionally found further afield; in mid-Essex, at Terling smock mill for example.  As hinted above troubles may develop, and this was so at West Wratting.

  At some time, with the heavy imposed load of sails and windshaft at the front, and downward strain on the overhung sheers at the rear, the cap frame became like a hogged ship, down at the ends and high in the middle.  To remedy this a system of twin central pylons, with iron tie-rods to cap extremities, was installed.  The rear sheers have been doubled, with full length timbers over their tops, possibly at the same time. The two pylons are of pine, about 7 inches by 5 inches, set on the central spindle beam, in line with the rear sheers.  They rise up about seven feet, are tied together with a pine beam near their tops, for stability, and have iron anchor plates at their heads, with provision for connection of ties, fore and aft. 

  For these plates, two stout hooked iron tie-rods, each in two parts, descend steeply forwards over brake and brakewheel, connecting with the weather beam.  Two similar ties, longer and shallower, are secured to eye bolts on the tail sheers well outside cap at rear, balancing the pull. The complete assembly, with cap frame, forms a double triangulated truss, giving an overtop hold on the affected parts.  Similar remedial schemes have been adopted at many mills; they make an interesting study.

  Knowing of his former connection with the mill, I showed my notes to Frank Farrow, of Great Wratting in Suffolk, and asked him some questions. He gave the following information:

“Father took the mill over in October 1911. She belonged to West Wratting Hall Estate, and was given a general overhaul at this time. The Derby peak runner stone was then new, and weighed 24 cwt (1219 kg). 

  The wedged joints to hemlaths on the patent sails, which you mention, are also found on Six-Mile Bottom post mill, and on one pair at Swaffham Prior tower mill.  Father said that Mr Noble told him that at one time West Wratting and Six Mile Bottom mills had all common sails.  Mr Noble then owned both mills.  He bought four patent sails coming off a mill being demolished (I believe a Soham mill), and put two on Six Mile and two on West Wratting.

  Hunt of Soham measured our common sails for new cloths, and I believe the length was 22 feet 6 inches by 4 feet 6 inches. We used the patent sails to the full, and spread enough cloth for working conditions. The only difficulty with cloths, in the Winter they would get frozen when wet or coated with snow. Also, if wet and not frozen, when spreading cloth water would run down your arms – most unpleasant. 

  In stormy weather the clouds must be watched for extra strong winds, also a quick change in direction, mostly from south to west. Standing where she does, the best winds were SE to NW.  Although the brake is a heavy one, it would not always hold the sails in a very strong wind.  A winch, chain and posts were used to wind her. If the curb was kept well greased, you could turn the winch with one hand.

  Stone raising was very good and easy, as you surmise; I have not used a better method. There was no trouble with the tentering; a governor strap would break sometimes, of course. When we were there, the ground floor was boarded, at a little lower level than the present concrete one. Even so the tentering screw was low and you could hit your head on it; we always used to leave it straight with the beam. 

  There was a grating near the doorway, which you could take up, and look under the floor. I can remember that the rats would get under there.

  On the countershaft driven from below the spur wheel, just back of the iron wood-cogged nut, was a wooden pulley for driving an oat crusher, and the outer (dresser) pulley was also used for a bean crusher. 

  The outside pulley was the engine drive used in Mr Tredgett’s time – he had the mill before us. There was a bevel on the end of the shaft inside, driving another on the east stone spindle.  One snag: if you wished to run the other pair of stones, you had to raise the runner off the crosshead(1).  This gear had been removed when we took over, and we never used an engine. 

  As to the kind of trade carried on, up to the First World War it was farm grist grinding for stock feeding, also wheat grinding for making flour.  As the War developed restrictions were imposed and father could not get enough flour out of a sack of wheat as required by the government, so he gave up making flour.  He started to make a little again after the War, but that trade never returned sufficiently to make it worthwhile. 

  We carried on grinding for cattle food until we left the mill. The decline in trade was due to farmers getting their own little plate mills, which were driven by oil engines.  I would add that no wheat was ground for flour during the last 4 or 5 years of our time, during which I worked her.

  On the death of the Squire, the Estate was sold up, and we left in October 1924.  The patent sails were then getting into a bad state, otherwise she was in fair working order.  Not long before, I had recogged the west stone nut, using beech, and dressed the peak runner stone. She was last used by myself in October 1924, and never used again.

(1) Mr Farrow writes, “The phrase “lift the runner stone off the crosshead”, was a phrase of father’s.  He meant, lift the runner so that the gimbal bar was up and out of the mace.”

YAXLEY, Old Stone Mill

Tower mill, gone


Dated 1671, the date being on the stonework inside the building, this small tower mill had a distinctive shape, being parallel-sided until near the curb at which point it was cambered inwards. It is said to have originally been a land lighthouse and to have borne the date 1500. It was built of dressed and rough stone to first floor level, with a moulded stone plinth, and above this was of brick, the whole being plastered. The cap had a petticoat of horizontal boards and the curb and skids were of wood.(1) 

(1) Peterborough Advertiser 14/1/1827; RW 19/4/50

YAXLEY, Farcet Road Mill

Tower mill, gone


The three-storey tower is thirty feet high. It was originally tailpole-winded; later a fantail was fitted, driving down to an internal rack. The wallower is of trundle wheel type, with 29 pegs of 5” pitch, 2 and a half inches in diameter, and 4 and a half inch face. The stone nuts were on octagonal tapers.(1)

(1) RW 19/4/50