PART TWO: POWER AND ENGINEERING 262 equipment which is to be powered outside the horse path. This form of horizontal machine is often to be found as a portable machine which can be taken round the farm to do various jobs. To the vertical and horizontal machines should be added two forms of animal-powered machines which are outside the above classification. In the oblique treadmill the animal, usually a horse, is harnessed firmly between two frames and stands on an obliquely-mounted belt which moves off from under his feet. The upper end of the belt is on the same shaft as a pulley wheel so that there is a considerable speeding up between the engine—often called a paddle engine—and the machinery, which could be a circular saw or a threshing drum. The other ‘oddity’ is the oblique treadwheel, which consists of a fairly small-diameter circular tread plate which has treads fixed radially on its upper face. The underside of the oblique treadwheel carries a gear wheel from which the drive is taken, and which is used for small tasks like churning butter. The ancient world We have considerable knowledge of the use of animal-powered engines in prehistoric and classical times, but no certainty of their form until the Roman period. The use of the vertical treadwheel for hoisting purposes is shown in a relief in the Lateran Museum. This shows a treadwheel with at least four operatives inside. The windlass on the shaft of this treadwheel is lifting a stone by means of two two-sheave pulleys in order to give a further 4:1 lift in addition to the advantage of the treadwheel. Ropes pass from the treadwheel at the bottom of a single boom to lift a stone on to the roof of a temple. While this is not the only example, the quality of this relief shows how skilled the Roman engineers were in being able to set up the treadwheel in a temporary setting such as a building site. The Romans were probably the originators of the hourglass animal- powered corn-grinding mill. There are examples of this form of direct-drive animalpowered mill in London, Pompeii, Capernaum in Israel, and Mayen in the Eifel region of Germany, the best being the row of four set up in a bakery in Pompeii; the example in the Museum of London, from a London site, is similar. The fixed stone of the mill is a single stone, circular in plan and finished in a long cone on a short cylindrical base. The runner stone, to use the analogy of the ‘normal’ pair of millstones, consists of a large stone block which is carved to form two connected shells in the form of an upright and an inverted cone. This sits over the base and is cut to be a close fit. The middle of the runner stone has sockets on either side of the waist to take the fixings of the rigid wooden frame to which the animal, usually an ass, was harnessed. The grain, fed into the inverted cone—in effect a hopper—works its way down and round the lower cone, and is ground by the motion of the runner stone on WATER, WIND AND ANIMAL POWER 263 it. The meal is collected from the base of the mill after it is ground, but there appears to be no means of collecting it mechanically; it just remained to be swept up. Another direct-drive animal-powered engine used in Roman times is the trapetum. This is an olive-crushing mill, and it has a successor of more recent times: the cider apple crusher (see p. 260). In the trapetum two crushing rolls, in the form of frustrums or spheres, rotate and move around a circular trough. The spheres are suspended just clear of the trough so that the olive pips are not crushed, making the oil bitter. The animal is harnessed to arms which are inserted in sleeves in the roller crushers so that the rollers rotate about the sleeves while describing a circular path in the trough. The central part of the trough is raised to form a pillar on which the arms and rollers are pivoted. In the fertile areas of the eastern Mediterranean there were several forms of water-raising device which were used principally for irrigation. Some of these are still in use today in the same manner as they were some 2000 years ago, except that they are more sophisticated in their construction. The chain of buckets, raised at first by the action of men on levers, was fitted with a crude arrangement of gears at quite an early date. An ox or camel could be harnessed to the arms on top of the gear wheel, and by the movement of the animal walking round the central point the gear wheel, engaging with the gears on the same shaft as the chain of buckets, could raise these to the surface, where they discharged automatically into irrigation ditches. Their successors, which can be found in Portugal, Spain and the Greek islands, are now made of metal, but are rarely to be found in use as they have been superseded by electric or diesel pumps. In a similar way a bucket was wound out of a well on a drum windlass mounted on an upright shaft which was turned by an animal walking round the shaft in a circular path. The animal would be harnessed to one end of an arm socketed into or housed around the shaft. This form of water-raising device can still be found, regrettably not in use, on the North Downs, between Canterbury and Maidstone, in Kent. Mediaeval and Renaissance Europe As with waterwheels and windmills, the sources of information on the use of animal-powered engines in the mediaeval period are only archival or iconographic. There are one or two examples of treadwheels in place in the cathedrals of Europe where they were installed as lifting devices for the maintenance of the stone walls, roofs and timbers of the tower, or of spires and high roofs. These date back to the mediaeval period, and we know that they also played a large part in the construction of the buildings themselves. As the great nave vaults were gradually being built the scaffolding followed the building from bay to bay. A treadwheel crane would be mounted on the PART TWO: POWER AND ENGINEERING 264 scaffolding, or on the top of a completed vault, and moved along as the work proceeded. Those which still remain are, of course, well constructed and properly built into permanent housings, but if they were used as part of the moveable scaffolding they could have been more crudely constructed. Some of the English survivors are interesting and worthy of note. At Tewkesbury there is a single rim supported off the shaft and windlass by a single set of spokes. A man worked the wheel by treading on the outside of rungs which project on either side of the rim. This example may date from about 1160 when the tower was completed. At Salisbury, a similar wheel in which the simple single rim is replaced by three rims, but which still has only one set of spokes, dates from about 1220. The conventional treadwheel, in which a man walks on the inside of a drum, can still be seen at Beverley Minster and at Canterbury. On the Continent examples of the treadwheel may be seen in Haarlem in the Netherlands and at Stralsund and Greifswald in the German Democratic Republic. While slaves and workmen had used the treadwheel to lift materials and water in the Roman and mediaeval periods, the deliberate use of machines as a punishment did not become general practice in Britain until the nineteenth century. Sir William Cubitt is thought to have invented the prison treadmill in about 1818, although he did not patent it. In this machine the prisoners trod the steps on the outside of a wheel which turned away underneath them. The power generated was used to grind grain into meal, to pump water or merely to work against a brake. The treadmills, of which the only survivors are at Beaumaris gaol in Anglesey and the one from York now at Madame Tussauds in London, appear to have been made from standard castings so that the length could be determined by the number of prisoners required to tread them. This form of punishment existed in nearly all British prisons until it was abandoned in about 1900. As with the watermill, the documentation of the form of the animal- powered engine can be seen in Agricola’s De Re Metallica of 1556 (see p. 232). The use of animal-powered machines in mining in the 1550s is also shown in the Kutna Hora Gradual which dates from the last years of the fifteenth century. This shows particularly accurately the use of a large-size windlass for winding ore out of mine shafts. The illustration shows four horses harnessed in this engine. What is more interesting in the history of technology is that this machine shows the horses to be harnessed outside a large-diameter gear wheel which engages with the windlass. The vertical horsewheel house containing the engine has a parallel in the preserved example at Kiesslich-Schieferbruch bei Lehesten in the DDR. While these iconographic examples are artistic, the details provided in De Re Metallica are factual, and appear quite workable. The horsewheel house (Book VI) with a conical roof has four arms to which eight horses can be harnessed. The upright shaft passes below ground where a crown wheel with peg teeth WATER, WIND AND ANIMAL POWER 265 engages with a pinion in which the teeth are carved out of a cylinder, rather like a lantern gear. The pinion then drives the lifting drum of a chain pump which is mounted on the same shaft. Again in Book VI there is a conventional treadwheel driving a chain pump through a train of a spur gear and a lantern gear. The evidence is all there to demonstrate a substantial use of animalpowered machines in the mediaeval period, and it is unfortunate that only very few examples survive to show how efficient they were. On ships, and sometimes on land, heavy loads such as the anchor and its cable or packages for transportation, were lifted by means of the capstan. This is usually a long wooden drum mounted on one deck with its head projecting above the main deck. This gives it stability when the load is taken up. Capstan bars are inserted in the head so that a large number of sailors can push on the bars and turn the cylinder. The load is drawn up by the chain or cable being wound on the lower portion of the drum. A ratchet stops the load pulling the chain off the drum again as it tries to sink back under its weight. As the industrialization of Europe grew in pace in the period following the 1500s, so the use of animal-powered machinery grew as well, although the number of these machines could never have been as great as the number of waterwheels, for they are more cumbersome and not necessarily as powerful. With the growth of printing, and with it the proliferation of wood-block illustrations (see Chapter 14), the designs of the various machines were published throughout Europe. Similarly, people travelling in Europe, either on the Grand Tour or as master craftsmen moving from job to job, were able to take the information on the many machines for use in other countries. One important book was Ramelli’s La Diverse et Artificiose Machine, published in 1588 in Paris. In this book there are many examples of animal-powered engines; some may be regarded as purely fanciful, but others, such as the horse-driven corn mill in figure CXXII, are examples of workable machines. This was followed by Zonca’s Novo Teatro di Machine et Edifici, published in 1607 in Padua. This showed similar examples to those above, and also the first example of the oblique treadwheel, driven by an ox, for grinding grain. The eighteenth century In the early 1700s the first really good millwrights’ books were published, true text-books with scale drawings and fairly complete constructional details. The great millwrighting books of Holland (see p. 251) were in circulation in Europe: it is known that John Smeaton had his own copies and used them. They were clearly intended for the new professionals, for they were written by millwrights and engineers. While these millwrights’ books were comprehensive in that they dealt with windmill and watermill construction, they also gave details of the construction of horse-driven corn mills and other horse engines. The use of PART TWO: POWER AND ENGINEERING 266 horses to drive corn mills in Dutch towns is unexpected, as there were windmills all round the towns and on the town walls in many cases. These horsedriven corn mills, called grutterij, were established at the back of bakers’ shops to grind buckwheat for the production of poffertjes and pancakes. In the eighteenth century the use of the high-level horse-driven engine became well established for industrial purposes, although it is now impossible to determine the scale of this introduction. In Europe the established use of the horse-driven corn mill is well documented, particularly by the presence of preserved examples in the open-air museums of the Netherlands, Germany and Hungary. In Hungary, for example, there are several horse-driven corn mills and a preserved example of the oblique treadwheel, as shown in Zonca, drove the corn mill from Mosonszentmiklos in the open-air museum at Szentendre. These appear to date from the eighteenth century, for although they do not have sophisticated cycloidal gearing, the cog and rung gearing has reached a high standard. In England there is a fine example of a horse-driven corn mill at Woolley Park in Berkshire, but there are not many records to show that other examples existed in substantial numbers. In industrial terms, too, there are not many records to identify particular sites where these machines were used. It is known, for example, that Strutt and Arkwright had a horse-driven cotton mill in Derbyshire before the foundation, by Arkwright, of the large water-driven mills in the Derwent valley. In Holland, the use of horse-driven machinery to drive oil-seed crushing mills was well known. In these mills, which exist in museums, the horse pulls round the great edge- runner stones, and by the same motion drives the oil stamps and the rotating ‘cracking’ plates, by means of trains of gears on the head of the shaft. Similar machines existed for the grinding of black powder in gunpowder works and for the grinding of pigments in colour mills. In the national open-air museum at Arnhem there is an example of a horse-driven laundry which was rescued from a site between Haarlem and Amsterdam. In going round the vertical shaft, the horse turned a shaft on which cams were mounted which effectively rotated and squeezed the clothes in three wooden tubs. These laundries, of which there were several near Amsterdam, provided a service for the twice- yearly spring and winter washes. The normal weekly wash of a town house was not done here, for after washing in the mechanical laundry, the linen would be bleached in the fields. High-level direct-drive mine windlasses must have been fairly numerous, as the illustrations from the English mining districts show many examples. The drawings of T.H.Hair in his book Sketches of the Coal Mines in Northumberland and Durham show one or two examples of these high-level winding drums with a good example as a vignette on the title page. This was published in 1839, long after the introduction of the steam-driven winding engine to the mines. We know from the insurance papers of 1777 from Wylam colliery, Northumberland, that there were five horse-driven winding engines (locally WATER, WIND AND ANIMAL POWER 267 called ‘whin gins’) there. Horse engines, erected temporarily on scaffolding, were needed when mine shafts had to be dug. There was one at East Herrington, near Sunderland, which was left in place to service the pumps in the pump shaft of this mine, and there is the preserved example at Wollaton Hall Industrial Museum, Nottingham, known to have been built in 1844 as a colliery gin, and which ended its days being used for shaft inspection and repair. The same type of horse-driven winding drum continued in use until much more recently in the Kimberley diamond mining field in South Africa and in the Australian goldfields. At the turn of the century, the ‘Big Hole’ in Kimberley was ringed with these winding drums. While the industrial use of horse-driven machinery remained low, the real growth in the use of the horse-driven engine was on farms in the last quarter of the eighteenth century. Andrew Meikle patented a horse-driven threshing drum in 1788 in Scotland, and this helped to overcome the shortage of labour which existed on farms in Scotland and the north of England, from which the country labourer had been driven to more remunerative work in the coalfields and the expanding industrial towns. These machines did not grow in number in the south of England where labour was still available to work on the land and where the ‘Captain Swing’ riots of the 1830s took place to protest against mechanization. Meikle’s horse engine was a high-level machine with a large gear wheel mounted so that the horses could be harnessed underneath it. Clearly, while it was set up in permanent structures attached to the barns, it could be used for other purposes such as chaff or turnip cutting, wood sawing and water pumping. The number of these high-level wooden horse engines in existence is extremely small, but the buildings which housed them can still be found in quite large numbers in north-east England. More than 1300 horsewheel houses have been identified in Kenneth Hutton’s paper ‘The Distribution of Wheelhouses in the British Isles’, in the Agricultural History Review, vol. 24, 1976. The nineteenth century The large number of horsewheel houses indicates the number of high-level horse-driven gear wheels which must have existed at one time. They were manufactured throughout the eighteenth and nineteenth centuries. Early in the nineteenth century the universal use of cast iron made it possible to introduce the low-level horse engine. In this the horse or horses went round the central shaft harnessed to the end of the horse arm. The central shaft was usually short and carried a small-diameter crown wheel of cast iron. The first gear wheel would engage with a smaller bevel wheel which could be connected with the farm machinery to be driven by means of a universal joint. Sometimes the frame carrying the horse wheel would carry a train of gears so that the PART TWO: POWER AND ENGINEERING 268 shaft, which is the final element in the engine, could rotate extremely fast in relation to the 4kph (2.5mph) which the horse imparted to the ends of the horse arms. If the machinery required to be driven with considerable rotational speed, then the horse engine could be connected with it by means of intermediate pulleys and belts. Examples of the low-level horse engine exist in which the engine is mounted on a frame with wheels so that it can be pulled around as necessary. One or two designs for threshing engines with integral horse engines are known and these were dismantled and placed on a frame so that the whole unit could be taken from farm to farm by contract threshers. These, of course, were displaced by the portable steam engine. The production of the low-level horse engine must have reached enormous numbers during the nineteenth century; so much so that competitions were held at the shows of the Royal Agricultural Society to evaluate the work done by these machines. The low-level gear came in several forms, but the type usually met with is the one in which there is no casing to protect the user from being trapped in the gear. Later, safety models were introduced in which all the gears were enclosed in a casing, so that all that was to be seen was the horse arm and upright shaft at the top, and the drive shaft and universal joint coming out at the bottom for connection to the machinery. The example of the safety gear produced by the Reading Iron Works in England, was a cylinder of iron some 90cm (3ft) high and 60cm (2ft) in diameter. Examples of this Reading safety engine have appeared in Western Australia, together with the ‘standard’ Reading Iron Works corn mill. This corn mill had one pair of stones, mounted on an iron hurst frame, driven by gears from the associated horse engine. The Reading Iron Works, which had previously been the firm of Barratt, Exall & Andrewes, maintained offices in Berlin and Budapest in the nineteenth century, and even printed their catalogues in Russian as well as other European languages. England exported a great many low-level horse engines. Hunt of Earls Colne and Bentall of Malden, both in Essex, and Wilder of Reading are names of manufacturers whose products have been found overseas. In the USA and Canada horse engines were required in large numbers and these countries produced their own models. The manufacturers were usually based in the prairie states, such as the Case Co. of Racine, Wisconsin. In the USA horse engines were considerably larger than in Europe, for on the vast prairies reaping machines had large blades and were hauled by teams of up to twenty-four horses. When the reaping had been completed, the horses were harnessed to low-level horse engines to drive the threshing machines. As a result of this, the horse arms grew in size and number so that they could take twelve horses rather than the three or four catered for by European designs. The horses were harnessed to the horse engine and the teamster then stood on the machine to ensure that the horses pulled their weight. In the USA, too, the paddle engine, or oblique treadmill WATER, WIND AND ANIMAL POWER 269 (see p. 262), was frequently to be found in farmyards where it was attached to saw benches or to farm machinery. These were worked by one or more horses and were usually made to be portable. The oblique treadmill for churning butter, and worked by dogs, was also known. On the dry chalk uplands of England low-level horse engines are occasionally to be found operating pumps to deliver water from deep wells to isolated houses. In other places they are to be found in use for haulage from small mine shafts such as the copper mines on the Tilberthwaite Fells in the English Lake District. Nowadays, animal-powered machines can still be found at work in countries where irrigation is necessary, such as Egypt, Syria and Iran, but these survivals are rare. Occasionally they are to be found in use on farms in Europe. It is to be regretted that so little remains of this element of natural-power machinery for it played a significant part in the history of agriculture, and a minor part in the development of industry. GLOSSARY Bell crank a means of turning a pulling motion at right angles. Two arms at right angles are mounted to pivot about a point between their tips. Cog and rung gears a gear system in which plain, unshaped teeth engage with a set of staves held between two flanged rings. Cycloidal gears gears formed to a precise profile so that when they engage they roll along the face of the teeth to give a smooth motion and not the striking effect of the cog and rung gear. Fantail a means of turning a windmill into the wind automatically. This consists of a set of blades mounted at the back of the mill at right angles to the sails, which rotate the cap by means of a gear train. Grain elevator a series of small rectangular buckets mounted on a continuous belt inside a double wooden shaft. Grain is poured in at the bottom of the rising shaft so that it falls into the buckets which empty themselves into a hopper at the top when the belt goes over the top pulley. Great spur wheel mounted on the upright shaft in a mill, drives the millstones by means of the stone nuts and stone spindles. Greek mill a mill in which a horizontal waterwheel is mounted on the same shaft as the runner millstone. As the horizontal waterwheel turns so the runner millstone is turned at the same speed. This type of watermill is in common use from Portugal across the Mediterranean area. Hemlath the longitudinal member at the outer edge of a sail frame. Horizontal feed screw a means of carrying meal horizontally in a watermill. A rotating shaft in a long square box or sheet metal tube carries a continuous screw of sheet metal or a series of small paddles set in a screw form. The meal is pushed along to the appropriate opening by the motion of the screw. PART TWO: POWER AND ENGINEERING 270 Horizontal waterwheel a waterwheel mounted to rotate in a horizontal plane so that its rotation is transmitted into the mill by means of a vertical shaft. Hurst frame the frame of stout timbers which carry the millstones. Often this frame is independent of the structural timbers of the mill. Impulse wheel waterwheels, or more particularly turbines, which are driven by the pressure of the water being forced on them through a nozzle, rather than by the weight of water flowing on to them directly. Lantern gears and pinions gears (resembling a lantern) having staves between two flanges, turned by pegs on the rim of another wheel. Mortice wheel a cast-iron wheel in which sockets in the rim are set to receive wooden gear teeth. Moulin pendant a form of watermill still to be found in France in which an undershot waterwheel is suspended in a frame so that the whole can be raised or lowered to meet variations in the water level caused by flood water. Norse mill another name given to the drive system found in the Greek mill (q.v.). This form of mill still exists in Scandinavia and was common in the north of Scotland and the Faroes. Overshot waterwheel a waterwheel in which the water is delivered to the top of the wheel so that it turns in the direction of flow. Panster Muhle the German equivalent of the French moulin pendant (q.v.) which can still be found in the German Democratic Republic. In some instances the frame carrying the waterwheel is hinged and raised by chains and large man-operated lifting wheels. Pit wheel name given to the first gear wheel in a watermill mounted on the waterwheel shaft. Because of its large size it usually runs in a pit on the inside of the wall which separates the waterwheel from the mill machinery. Querns name given to primitive hand-operated millstones. These can be stones between which the grain is ground by rubbing or in which an upper flat-faced circular stone is rotated over a fixed flat-faced stone. Stream waterwheel waterwheel in which there is no head of water but in which the floats are driven round by the flow of water striking them. Tail water the water emerging from the bottom of a waterwheel while it is turning. Undershot waterwheel a waterwheel in which there is a small head of water driving the wheel around. The water hits the wheel at about 60° below the horizontal line through the centre of the wheel. Vertical waterwheel waterwheel mounted on a horizontal axis and rotating in a vertical plane. Vitruvian mill the simplest form of watermill with a vertical waterwheel. The waterwheel is coupled by a pit wheel to a single runner millstone by means of a gear on the stone spindle. It is so called because it is described by Vitruvius in the tenth book of De Architectura which was published in about 20 BC. Wallower a gear wheel which transmits the drive from the pit wheel to the upright shaft in a watermill or from the brake wheel on the windshaft to the upright shaft in a windmill. WATER, WIND AND ANIMAL POWER 271 FURTHER READING Baker, T.L. A field guide to American windmills (University of Oklahoma Press, Norman, 1985) Hunter, L.C. Waterpower, a history of industrial power in the United States, 1780–1930 (The University Press of Virginia, Charlottesville, 1979) Major, J.K. Animal-powered engines (B.T.Batsford, London, 1978) Major, J.K. and Watts, M. Victorian and Edwardian windmills and watermills from old photographs (B.T.Batsford, London, 1977) Reynolds, J. Windmills and watermills (Hugh Evelyn, 1970) Reynolds, T.S. Stronger than a hundred men, a history of the vertical water wheel (Johns Hopkins University Press, Baltimore, 1983) Syson, L. The watermills of Britain (David and Charles, Newton Abbott, 1980) Wailes, R. Windmills in England, (The Architectural Press, London, 1948) —— The English windmill (Routledge & Kegan Paul, London, 1967) . the maintenance of the stone walls, roofs and timbers of the tower, or of spires and high roofs. These date back to the mediaeval period, and we know that they also played a large part in the construction. be harnessed to the arms on top of the gear wheel, and by the movement of the animal walking round the central point the gear wheel, engaging with the gears on the same shaft as the chain of buckets,. remains of this element of natural-power machinery for it played a significant part in the history of agriculture, and a minor part in the development of industry. GLOSSARY Bell crank a means of