reverse overshot water wheel brands

Frequently used in mines and probably elsewhere (such as agricultural drainage), the reverse overshot water wheel was a Roman innovation to help remove water from the lowest levels of underground workings. It is described by Vitruvius in his work

The Roman author Vitruvius gives explicit instructions on the construction of dewatering devices, and describes three variants of the "tympanum" in Chapter X of

Pliny the Elder is probably referring to such devices in a discussion of silver/lead mines in his silver in his time, many of the silver mines having been started by Hannibal. One of the largest had galleries running for between one and two miles into the mountain, "water-men" (in Latin "aquatini") draining the mine, and they

That they stood suggests that they operated the wheels by standing on the top to turn the cleats, and continuous working would produce a steady stream of water.

Fragments of such machines have been found in mines which were re-opened in the Victorian era in Spain, especially at Rio Tinto, where one example used no less than 16 such wheels working in pairs, each pair of wheels lifting water about 3.5 metres (11 ft), so giving a total lift of 30 metres (98 ft). The system was carefully engineered, and was worked by individuals treading slats at the side of each wheel. It is not an isolated example, because Oliver Davies mentions examples from the Tharsis copper mine and Logroño in Spain, as well as from Dacia. The gold deposits in Dacia, now modern Romania were especially rich, and worked intensively after the successful Roman invasion under Trajan. According to Oliver Davies, one such sequence discovered at Ruda in Hunedoara County in modern Romania was 75 metres (246 ft) deep. If worked like the Rio Tinto example, it would have needed at least 32 wheels.

One such wheel from Spain was rescued and part of it is now on display in the British Museum. Some of the components are numbered, suggesting that it was prefabricated above ground before assembly in the underground passages. In the 1930s, a fragment of a wooden bucket from a drainage wheel was found in deep workings at the Dolaucothi gold mine in west Wales, and is now preserved in the National Museum of Wales in Cardiff. It has been carbon dated to about 90 AD. From the depth of 50 metres (160 ft) below known open workings, it can be inferred that the drainage wheel was part of a sequence just like that found in Spain. The shape of the edge of one of the lifting buckets is almost identical with that from Spain, suggesting that a template was used to make the devices.

They were also used in series, so increasing the lift of water from the workings. However, they must have been more difficult to operate since the user had to stand on a slanting surface to turn the screw. The steeper the incline, the greater the risk of the user slipping from the top of the screw. No doubt the reverse water wheel was easier to use with a horizontal treading surface. On the other hand, the screw could be operated by a crank handle fitted to the central axle, but would be more tiring since the weight of the operator does not bear on the crank, as it does when trod from above.

Like the reverse water wheel, the cochlea was used for many other purposes apart from draining mines. Irrigation of farmland would have been the most popular application, but any activity which involved lifting water would have employed the devices.

Multiple sequences of water wheels were used elsewhere in the Roman Empire, such as the famous example at Barbegal in southern France. This system was also a stack of 16 wheels but worked like a normal overshot wheel, the wheels driving stone mills and used to grind grains. The water mills were worked from a masonry aqueduct supplying the Roman town at Arles, and the remains of the masonry mills are still visible on the ground today, unlike the underground drainage systems of the mines, which were destroyed by later mining operations. Other such sequences of mills existed on the Janiculum in Rome, but have been covered and changed by later buildings built on top of them.

Water wheel design has evolved over time with some water wheels oriented vertically, some horizontally and some with elaborate pulleys and gears attached, but they are all designed to do the same function and that is too, “convert the linear motion of the moving water into a rotary motion which can be used to drive any piece of machinery connected to it via a rotating shaft”.

Early Waterwheel Design were quite primitive and simple machines consisting of a vertical wooden wheel with wooden blades or buckets fixed equally around their circumference all supported on a horizontal shaft with the force of the water flowing underneath it pushing the wheel in a tangential direction against the blades.

These vertical waterwheels were vastly superior to the earlier horizontal waterwheel design by the ancient Greeks and Egyptians, because they could operate more efficiently translating the hydrokinetic energy of the moving water into mechanical power. Pulleys and gearing was then attached to the waterwheel which allowed a change in direction of a rotating shaft from horizontal to vertical in order to operate millstones, saw wood, crush ore, stamping and cutting etc.

Most Waterwheels also known as Watermills or simply Water Wheels, are vertically mounted wheels rotating about a horizontal axle, and these types of waterwheels are classified by the way in which the water is applied to the wheel, relative to the wheel’s axle. As you may expect, waterwheels are relatively large machines which rotate at low angular speeds, and have a low efficiency, due to losses by friction and the incomplete filling of the buckets, etc.

The action of the water pushing against the wheels buckets or paddles develops torque on the axle but by directing the water at these paddles and buckets from different positions on the wheel the speed of rotation and its efficiency can be improved. The two most common types of waterwheel design is the “undershot waterwheel” and the “overshot waterwheel”.

The Undershot Water Wheel Design, also known as a “stream wheel” was the most commonly used type of waterwheel designed by the ancient Greeks and Romans as it is the simplest, cheapest and easiest type of wheel to construct.

In this type of waterwheel design, the wheel is simply placed directly into a fast flowing river and supported from above. The motion of the water below creates a pushing action against the submerged paddles on the lower part of the wheel allowing it to rotate in one direction only relative to the direction of the flow of the water.

This type of waterwheel design is generally used in flat areas with no natural slope of the land or where the flow of water is sufficiently fast moving. Compared with the other waterwheel designs, this type of design is very inefficient, with as little as 20% of the waters potential energy being used to actually rotate the wheel. Also the waters energy is used only once to rotate the wheel, after which it flows away with the rest of the water.

Another disadvantage of the undershot water wheel is that it requires large quantities of water moving at speed. Therefore, undershot waterwheels are usually situated on the banks of rivers as smaller streams or brooks do not have enough potential energy in the moving water.

One way of improving the efficiency slightly of an undershot waterwheel is to divert a percentage off the water in the river along a narrow channel or duct so that 100% of the diverted water is used to rotate the wheel. In order to achieve this the undershot wheel has to be narrow and fit very accurately within the channel to prevent the water from escaping around the sides or by increasing either the number or size of the paddles.

The Overshot Water Wheel Design is the most common type of waterwheel design. The overshot waterwheel is more complicated in its construction and design than the previous undershot waterwheel as it uses buckets or small compartments to both catch and hold the water.

These buckets fill with water flowing onto the wheel through a penstock design above. The gravitational weight of the water in the full buckets causes the wheel to rotate around its central axis as the empty buckets on the other side of the wheel become lighter.

This type of water wheel uses gravity to improve output as well as the water itself, thus overshot waterwheels are much more efficient than undershot designs as almost all of the water and its weight is being used to produce output power. However as before, the waters energy is used only once to rotate the wheel, after which it flows away with the rest of the water.

Overshot waterwheels are suspended above a river or stream and are generally built on the sides of hills providing a water supply from above with a low head (the vertical distance between the water at the top and the river or stream below) of between 5-to-20 metres. A small dam or weir can be constructed and used to both channel and increase the speed of the water to the top of the wheel giving it more energy but it is the volume of water rather than its speed which helps rotate the wheel.

Generally, overshot waterwheels are built as large as possible to give the greatest possible head distance for the gravitational weight of the water to rotate the wheel. However, large diameter waterwheels are more complicated and expensive to construct due to the weight of the wheel and water.

When the individual buckets are filled with water, the gravitational weight of the water causes the wheel to rotate in the direction of the flow of water. As the angle of rotation gets nearer to the bottom of the wheel, the water inside the bucket empties out into the river or stream below, but the weight of the buckets rotating behind it causes the wheel to continue with its rotational speed.

Once the bucket is empty of water it continues around the rotating wheel until it gets back up to the top again ready to be filled with more water and the cycle repeats. One of the disadvantages of an overshot waterwheel design is that the water is only used once as it flows over the wheel.

The Pitchback Water Wheel Design is a variation on the previous overshot waterwheel as it also uses the gravitational weight of the water to help rotate the wheel, but it also uses the flow of the waste water below it to give an extra push. This type of waterwheel design uses a low head infeed system which provides the water near to the top of the wheel from a pentrough above.

Unlike the overshot waterwheel which channelled the water directly over the wheel causing it to rotate in the direction of the flow of the water, the pitchback waterwheel feeds the water vertically downwards through a funnel and into the bucket below causing the wheel to rotate in the opposite direction to the flow of the water above.

Just like the previous overshot waterwheel, the gravitational weight of the water in the buckets causes the wheel to rotate but in an anti-clockwise direction. As the angle of rotation nears the bottom of the wheel, the water trapped inside the buckets empties out below. As the empty bucket is attached to the wheel, it continues rotating with the wheel as before until it gets back up to the top again ready to be filled with more water and the cycle repeats.

The difference this time is that the waste water emptied out of the rotating bucket flows away in the direction of the rotating wheel (as it has nowhere else to go), similar to the undershot waterwheel principal. Thus the main advantage of the pitchback waterwheel is that it uses the energy of the water twice, once from above and once from below to rotate the wheel around its central axis.

The result is that the efficiency of the waterwheel design is greatly increased to over 80% of the waters energy as it is driven by both the gravitaional weight of the incoming water and by the force or pressure of water directed into the buckets from above, as well as the flow of the waste water below pushing against the buckets. The disadvantage though of an pitchback waterwheel is that it needs a slightly more complex water supply arrangement directly above the wheel with chutes and pentroughs.

The Breastshot Water Wheel Design is another vertically-mounted waterwheel design where the water enters the buckets about half way up at axle height, or just above it, and then flows out at the bottom in the direction of the wheels rotation. Generally, the breastshot waterwheel is used in situations were the head of water is insufficient to power an overshot or pitchback waterwheel design from above.

The disadvantage here is that the gravitational weight of the water is only used for about one quarter of the rotation unlike previously which was for half the rotation. To overcome this low head height, the waterwheels buckets are made wider to extract the required amount of potential energy from the water.

Breastshot waterwheels use about the same gravitational weight of the water to rotate the wheel but as the head height of the water is around half that of a typical overshot waterwheel, the buckets are a lot wider than previous waterwheel designs to increase the volume of the water caught in the buckets.

The disadvantage of this type of design is an increase in the width and weight of the water being carried by each bucket. As with the pitchback design, the breastshot wheel uses the energy of the water twice as the waterwheel is designed to sit in the water allowing the waste water to help in the rotation of the wheel as it flows away down stream.

Historically water wheels have been used for milling flour, cereals and other such mechanical tasks. But water wheels can also be used for the generation of electricity, called a Hydro Power system.

By connecting an electrical generator to the waterwheels rotating shaft, either directly or indirectly using drive belts and pulleys, waterwheels can be used to generate power continuously 24 hours a day unlike solar energy. If the waterwheel is designed correctly, a small or “micro” hydroelectric system can produce enough electricity to power lighting and/or electrical appliances in an average home.

Look for Water wheel Generators designed to produce its optimum output at relatively low speeds. For small projects, a small DC motor can be used as a low-speed generator or an automotive alternator but these are designed to work at much higher speeds so some form of gearing may be required. A wind turbine generator makes an ideal waterwheel generator as it is designed for low speed, high output operation.

If there is a fairly fast flowing river or stream near to your home or garden which you can use, then a small scale hydro power system may be a better alternative to other forms of renewable energy sources such as “Wind Energy” or “Solar Energy” as it has a lot less visual impact. Also just like wind and solar energy, with a grid-connected small scale waterwheel designed generating system connected to the local utility grid, any electricity you generate but don’t use can be sold back to the electricity company.

In the next tutorial about Hydro Energy, we will look at the different types of turbines available which we could attach to our waterwheel design for hydro power generation. For more information about Waterwheel Design and how to generate your own electricity using the power of water, or obtain more hydro energy information about the various waterwheel designs available, or to explore the advantages and disadvantages of hydro energy, then Click Here to order your copy from Amazon today about the principles and construction of waterwheels which can be used for generating electricity.

Water has been used to power simple and complex mills since antiquity. In colonial America, mills were powered by wooden waterwheels, but as technologies and manufacturing changed during the 19th century, water turbines began to be used more and more. In the period of 1850-1880 dozens of American manufacturers made cast iron turbines of nearly every conceivable configuration. Turbines could be readily ordered in different sizes that were suited for the specific water flow, shafting, and gearing needed for a particular mill. Turbines aren’t as susceptible to reduced flow when the water levels in the turbine pit are high or flooded. Perhaps best of all, turbines were iron and therefore did not require constant repair of a wooden waterwheel that began to rot from intermittent soaking even before installation was complete.

The vertical water wheels has three main types- (1) the overshot(including the overshot and pitch-backvarieties); (2) the breastshot (including the low, middle and high breast shot varieties); (3)the undershot (including the undershot and flutter wheel). The namesindicate the point at which the water enters the wheel. If you look at andface the water wheel from the side and regard it as a clock face. Then onlythe overshot would revolve in a clockwise direction while the pitch-back,the breast shot and undershot water wheels revolve in an counterclockwisedirection.

The development of the mechanized factories both in England and the Unitedstates led to efforts to improve the efficiency of existing water wheels.The British engineer named John Smeaton in the eighteen century analyzedthe relative efficiency of two forms of water wheels, the undershot andthe overshot. "The average overshot wheel was far more efficient thanthe undershot, about 65% as opposed to 25%. The undershot wheel is an impulsewheel, since the water imparts its energy by pushing. If the hillside issteep, the water moves fast at the bottom and can push impressively againstthe paddles of an undershot wheel. The overshot wheel is a gravity wheel.It is a series of buckets attached to the outside of a big circle. The watergoes into a container at the top and drops all the way down." In the1840"s the Franklin Institute conducted tests in the United States, probingthe efficiencies of water wheels once and for all.

The overshot water wheeldirects is water onto the wheelto turn in the same direction without changing its direction. They are usuallyused on falls of over ten feet. The water is conveyed to the top of thewheel by a wooden trough or sluice box and fed into the buckets. The waterfrom the sluice box and the chute let the water into the buckets of thewheel from the control gate. The buckets are formed by boards set at anangle toward the stream and the ends or sides of the boards are set intoslots in the sides of the wheel. The depth of the shrouds varied but usuallyit was from 9 to 15 inches. The bottom edges of the front bucket boardsare fastened to the sole or drum formed by planks secured to the insideend of the shrouds. The seams are often covered with batten to prevent leakageof water. This type of water wheels is referred to as a bucket wheel. Thepower generated by an overshot water wheel depends almost entirely on theweight of the water in the buckets, and the forward momentum of the wateras it enters the buckets adds slightly to the increment of the wheel"s power.

The water wheel moves in the same direction of the stream. The wheel getsits benefit from the whole initial velocity and impulse of the water. Theadvantage will be lost of the bottom of the wheel is immersed in water andbegins moving against the current. It is only possible for the wheel toturn above the tail water. It the bottom portion begins to become coverimmersed in water this effect called back watering. In the case of an overshotwater wheel it will obstruct and impede its movement because air becomestrapped in the buckets as the water wheel is rotating. The direction ofthat the overshot water wheel turns in back water tends to draw floatingdebris into the water wheel and do damage to it. Another great problem withovershot water wheels is that often the water is directed from the chuteonto the wheel too far forward of the vertical center of the water wheeland too much water flies over the wheel and never enters the buckets.

The end of the water box and the end of the chute attached to it shouldbe just behind the vertical center so when the water enters the wheel itis just behind the vertical center. In this way the wheel takes full advantageof the water and the fall available. The general rule for building an overshot water wheel is to allow a foot above and a foot below the wheel subtractedfrom the available fall. This will give you the largest water wheel thatcould be possibly be constructed. I said to allow a foot above the wheelbut this does not mean that the water should ever drop upon the water wheelfrom the end of the chute by one foot. This is to allow the constructionof the sluice box, water box and its supports behind the back curve of thewater wheel on the upstream side only. The water should exit the chute andmove only in the direction of the turning water wheel and the stream andnot downward. One foot (or more) should be allow under the water wheel toallow the water to flow away from the water wheel. Then by the time thewater flows down the tail race to pass the end of the building it shouldhave dropped a total of three feet from the bottom of the water wheel.

If water is directed upon the water wheel not in the direction the waterwheel rotates a phenomenon will develop known as "shock" whichwill retard and in many cases stop the water wheel from turning especiallyin water wheels that are out of balance. Generally only wooden water wheelssuffer for being out of balance but rebuilt metal wheels sometimes alsohave this problem. The balance of the water wheel will greatly effect ifability to rotate properly. An out of balance water wheel will not rotateproperly. If shock is effecting a wooden water wheel it will sit there forhours without turning unless it is given a "kick" start. An outof balance water wheel will slow in its rotation when it reaches an imbalancepoint. An out of balance wheel with out an internal load will sometimesbegin to turn backwards and seesaw back and forth until it stops with theheavy end downward. A hidden water jet spray under the sluice box will wetthe whole water wheel and help improve this problem. It should be turnedoff in the winter months to prevent ice on the water wheel.

One of the largest water wheel in the United States was the constructedby Henry Burden, a Scottish born iron worker, near Troy, New York. He builtan over shot water wheel in 1851. It was 69 feet in diameter by 22 feetwide. It had a cast iron axle, wrought iron rods for spokes. The shroudingbeing made of cast iron sections, buckets of Georgia Pine, with iron reinforcing.The Burden wheel developed 278-280 horse power, with an efficiency of 80%to 84.25%. Today the largest remaining water wheel is the Fairwater Wheel,once part of the Fairwater Electric Company, Fair Water, Wisconsin. Thelargest water wheel constructed by the Fitz Water Wheel Company, Hanover,Pennsylvania. It is 50 Feet in diameter Steel Overshoot Water Wheel. Builtin 1924, the 29 ton wheel is 10 feet wide, and produced about 140 horsepower.The largest vertical water wheels in the world are the Noria Water Wheelsfound in Syria and Jordan. They are located in Hama that is a river town,built on the banks of the Orontes. The town is famous for the 17 huge woodenwater wheels, known as noria, which once scooped water from the river anddeposited it into the aqueducts, which then supplied homes, public buildingsand farms. These wheels are about 20 meters (90 feet) in diameter and stillturn today, although their water is not used. The noria situated in thetown center are located in a public park and the Four Norias of Bichriyatare situated on a weir about 1 kilometers up-river from the town center.The largest noria is known as Al-Mohammediyyah.

The pitch-back water wheel is another modification form of theovershot water wheel. This type of over shot water wheel the water is carriedto the back of the water wheel or over the top of the wheel were it is introducedinto the buckets and the water wheel turns in a pitch-back direction tothat of which it was moving in the sluice box. The buckets of the pitch-backare set at an angle opposite to that of an overshot. The end of the sluicebox and the control gate are adapted so that the water is fed downward intothe buckets at the reverse direction to the flow of the stream, thus causingthe wheel to revolve in the opposite direction. Behind the wheel is an archof stone, wood or metal known as an apron, usually of the same radius atthe wheel. The edge of the buckets run close to this apron to confine thewater and prevent it form spilling from the buckets before arriving at thelowest point of the fall. Like the overshot water wheels the pitch-backwater wheels derive most of their power from the weight of the water inthe buckets, but they receive a certain amount of additional impulse fromthe water as it is fed in and changes direction from the gate.

The wheel thus runs in a contrary direction to that of the head stream,and in the turn (some have said) it looses some of the impulse of the water.The upper part of the water wheel may turn contrary to that of the streambut the lower part of the water wheel turns in the direction of the downstream, therefore the tail water is less immersed than the over shot. Inthis case the pitch-back is more like a larger breast shot water wheel thana true overshot. The pitch-back runs in the same direction as that of abreast shot and it may be arched into the wheel like that of a breast shot.Many of the back of the pitch-back have an arch, apron or shroud that helpshold the water into the wheel, and prevents winds from blowing it out.

The largest metal water wheel in the world is the Lady Isabella, the LaxeyWheel on the Isle of Man, United Kingdom, pitch-back water wheel 72 1/2feet in diameter by 6 feet wide. The water wheel was connected to two armsthat each operated cranks that pumped air into mines.

The breast shot water wheel was the most common water wheel foundpowering American industry up until the 1840"s when the French developedthe water turbine from our application of the tub water wheel. In many casesthe breast shot water wheels and undershot water wheels are of larger diameterthan the overshot and pitch-back water wheels. The ordinary breast shotwater wheel the water comes into the water wheel about at the center axispoint. Some high breast shot water wheels the water is applied to the upwardtop of the water wheel. The weight of the water multiplied by the heightof decent and not by just its impulse yields effective power. This typeof water wheel has its lower upstream side or quarter encased by an archor apron. It is made to fit closely to the rim of the water wheel to preventthe loss of water from moving under the wheel and thus keeping more waterin the buckets keeping the water wheel more efficient.

The breast shot water wheel would have a wooden apron or breast behind theback one third of the water wheel. Once the water wheel is constructed orinstalled no one would be able to see this feature (but I think it shouldstill be constructed). I would build the basic simplified frame work ofwood but instead of using wooden boards or planks, I would use marine plywoodscrewed down the the wooden frame work. The wooden frame work underneathwould be bolted into the concrete slap at the bottom of the water wheelpit so it would not move or lift up if the water wheel were to ever turn.The surface wood of the breast should be "one" inch away fromthe curve of the water wheel. This is why this work should be done withgreat care and thought.

A breast shot water wheel is most commonly used in falls of between 6 to10 feet. These water wheels are constructed very similar to that of theovershot and pitch back design. Both often have elbow buckets. A breastshot is called a breast shot because behind and below where the water entersthe water wheel is a breast or apron. These are usually fitted one inchaway from the water wheel to retain the water in the buckets and make thewater wheel more efficient. The wooden breast was most common in America.In England and Europe it was common to have a stone breast, extended alongthe lower curve of the water wheel just beyond its vertical center.

The breast shot water wheel came in three different types: the middle, lowand high breast shots. The middle and low breast shot water wheels had deeperbuckets to deal with the increased volume of water required for the lowhead of water to develop power equivalent to that obtained by a high breastshot water wheel. A high breast shot water wheel would then have elbow buckets.A breast shot water wheel combined both the weight and impulse of the waterin their operation, and these water wheel were larger in diameter and widerthan many other water wheels. They were often well designed wheel that madethem very popular with industry.

One of the big differences between that of a breast shot water wheel andthat of the overshot and pitch-back is that the breast shot water wheelis much wider. An efficient type of apron would terminate with a step downwardof about 6 inches usually about a foot before the lowest point in the run.This would enable the water to be discharged rapidly from the buckets soas not to impede the upward motion of the wheel. In the middle and low breastshot water wheels the buckets are deeper as to deal with the increased volumeof water required for the lower head of water to develop power equivalentto that obtained by a high breast shot water wheel. Breast shot water wheelssuffer less from the problems of back watering because the wheel is turningin the same direction that the water is flowing down the tail race and ittends to push the water way from the wheel as it rotates. Another advantageof the breast shot water wheel operating in back water is that the directionof rotation pushes the floating debris away from the water wheel and notdamage the wheel.

The undershot water wheel is used on falls with very low head,where there may be only a slight fall to a stream. The wheels are foundusually with less than 4 feet or with no head at all. These water wheelsare moved entirely by the impulse of the water and consequently requiredmuch greater quantities of water to produce the same power as developedby the overshot, pitch-back and breast shot water wheels.

They are mainly found on tidal mills and boat or floating mills. The simpleform of the water wheel is that of a paddle wheel. They may only be placedwere they dip into the current and relay mainly on the movement of the waterthan by any fall. The weight of the water is not applied. The undershotwater wheels usually have no sole or shrouding. Of the three types of verticalwater wheels, the undershot is the least efficient and the power developedbeing comparatively small to that of the size of the wheel and the amountof water that moves it.

In order to make the undershot water wheel more efficient, a portion ofthe periphery of the wheel from the point of impact of the water to a pointbelow the center of the wheel is surrounded by a casing or dip called anarch. The inside of the wheel should be in cased by a sole or drum boardsand the sides shrouded around the periphery. A gate or fore bay should directthe water to the wheel. Undershot water wheels are designed open so if theriver or the tide rises on the wheel, the water wheels is open enough soit will simply stop turning and will not be damaged by the rising water.Pitch-back, breast shot and undershot water wheels do not have the nostalgicromance that a turning overshot water wheels have, they simply fill theair with a spray of water droplets as they rotate.

The velocity of the periphery of an undershot water wheel is usually from500 to 600 feet a minute and that of the breast shot or overshot water wheelis 300 to 450 feet per minute. Generally the larger the diameter that thewater wheel is constructed the slower the slower the water wheel will rotate.A wooden water wheel will only turn so fast before it tares itself apart.The overshot water wheel is usually not suitable for heads less than 8 feetor beyond 40 to 45 feet. The size and great weight involved may preludethem from being built as a rule beyond a given limit. This does not meanthat there were not water wheels much larger. There was a wheel in GreatBritain, at Greenock, 70 feet 2 inches in diameter by 13 feet wide, with160 buckets, having a depth of 17 inches. The fall of this wheel was 66feet, and it used 2,266 cubic feet of water per minute thus producing somewherearound 200 horse power.

The construction of these type of water wheels differed little from thatof other wheels except that the buckets were replaced by radial floats.The early undershot water wheels usually hand floats constructed of flatboards with no right angles or sole boards on the inside rim of the wheel.Some in later years were encased for increased efficiency by having thesebacks fitted to prevent the water from shooting over the floats. Some undershotwater wheels the floats are fitted into slots in deep shrouds or rims andothers the rims are not so deep but were thicker timber that was mortisedand had short protruding arms or starts driven into them so the floats couldbe fastened such as in a flutter wheel. Often from the gate or shut of theundershot water wheels the water flows or moves downward path to strikethe floats by an enclosed channel or ramp. The lower the water is channeledto the undershot the further forward of the vertical center the ramp extendsbeyond the water wheel. But the higher the water leaves the gate and thesteeper the ramp the farther behind the vertical center the ramp changesdirection and then levels off and extends outward from the water wheel.These channels or ramps were often built of stone or wood. They were closefitting aprons but generally not the tight fitting curve that the pitch-backor breast shot had. The undershot water wheels were built from about 10to 25 feet in diameter. The floats were from 14 to 16 inches apart at thecircumference of the wheel and about 12 to 28 inches in depth.

The buckets of these type of water wheels are either straight or flat, curvedor have "kneel buckets" or elbow buckets. The curved are generallyiron or steel. The kneel or elbow buckets and flat buckets are constructedon wooden water wheels. The curved buckets are made to retain water to itslowest point as possible and in many respects are superior to that of theelbow bucket. The power may be taken off by a torsion, that is a pulleyor gear mounted to the axle of the shaft or bolted in segments to the armsof the water wheel near the periphery, by means of a pinion engaging theteeth of the water wheel. Originally the gear was attached to the segmentalsections of the shrouding or rim of the water wheel. But because of theproblems in keeping a wooden water wheel balanced and in proper "round,"the gear was then placed on the arms of the water wheel. This was more effectiveon the down going side than on the ascending side.

In no way is the progress in any branch of art or industry more strikinglyillustrated than by a glance at the methods in use a century or more ago.The annals of the American Society of Civil Engineers are supposed to bea repository of American practice and American methods in engineering. Thewriter, therefore, deems it no un worthy task to collect for preservationtherein such examples as he can of the motors and methods employed by ourancestors of the preceding century in availing themselves of the power ofwater.

The sources of information available to the writer are: (1) Such isolatedexamples as have come within his knowledge and recollection. (2) The drawingsand sketches extant in old books, which are usually mere hints and indications,requiring to be carefully studied and pieced out in order to yield any intelligentnotion of methods of construction. Of these the book of Oliver Evans exceedsall others in value. (3) Suits at law for the interpretation of old grantsof water, in which he has been employed as expert, sometimes involving aninjury into the methods and appliances in use at the date of the grant.,From the testimony and traditional knowledge of old millwrights, and suchmeager records as are available, some knowledge can be obtained.

Up to the beginning of the present century the chief and almost the onlyapplication of water power was for grinding grain and sawing lumber. Occasionallya wheel was set up, to create a blast for a foundry, or for fulling cloth,or the carding wool, the spinning and weaving being carried on in the household.

A wooden water wheel consists in general of five principle parts, theshaft, the arms, the shrouding, the soling, and the floats. It is only inthe latter element and in the mode of letting on the water that any distinctionexists between the overshot, the undershot and the breast wheel. The shaftwas an oak log 18 to 30 inches in diameter, dressed to a square, circularor polygonal form, with iron bands and gudgeons. There were two methodsin use of attaching the arms to the shaft. The method of clasp arms wasnot so common in this country as that although much used in Europe. Theshaft was squared at the place of application of the arms, or, if octagonal,was made square by the insertion of corner blocks. The arms were halvedor locked together and set firmly upon the shaft by means of wedges. Theadmitted of some adjustment of the wheel with reference to the shaft. Thiswas a very strong and durable arrangement for wheels up to 14 feet in diameter.Beyond that size the four pieces forming the arms would not give sufficientsupport to the shrouding, and the additional pieces were inserted, withthe blocks on which they were footed. These were notched to the timbersand fastened with pins or keys.

The second method of inserting the arms is compass arms. Though the shaftis here represented as round, it was more commonly dressed to a polygonalform - six or eight sides, rounded at the ends to receive the bands. Thearms were inserted in mortises passing through the shaft. They were notchedand locked together in the center of the shaft. This method required thelength of the mortises to exceed the width of the arms by an amount sufficientto admit of their insertion. The widest vacancy thus made was closed bya heavy oak key solidly confining to the arms. A wheel might have six arms,each of the three pieces forming the arms being cut away to the extent oftwo thirds of its width. The same construction is used for a wheel of eightarms, each of the four pieces being three fourths cut away. When the numberof arms exceeded eight, the additional arms were inserted into the arm nextto it diagonally in the middle.

All wheels run upon iron gudgeons inserted into the ends of the shafts.These are cast iron gudgeons. The part inserted in the wood is a cross offour feathers coinciding with a shaft in diameter. It is confined by heavybands, driven on hot. A wrought iron gudgeon it is inserted in a mortisecut from the outside of the shaft to a depth sufficient to bring the gudgeonto its proper position. After driving on the bands, the mortise is closedwith keys and wedges driven with great force. The wood is further compressedby driving thin wedges into the end of the shaft.

The shrouding consists of segmental pieces of 3 or 4 inch plank, forminga ring like the fellows of a wheel. They are attached to the arms in differentways. Halved and pinned or forked which creates a wheel with radial floats.With shrouding of sufficient thickness the arms are attached with mortiseand tenon, which simplifies the insertion of the floats. The shrouding piecesare halved and pinned to one another at their ends, and where the solingis wanting the joints are strengthened with splicing pieces.

The floats were sometimes inserted in grooves cut in the shrouding, sometimesmerely "sprigged" to the shrouding and confined at their endsby blocks of one inch board, fitted in an nailed to the shrouding. In theearlier forms of breast and overshot wheels, they were inserted as flatfloats, rather than elbow buckets. They were different in the later forms,as will appear further on. The space contained between two consecutive floatswas called a bucket.

In the high breast wheel and the manner of letting on the water, the partloaded with water is surrounded, at a distance of about 3/4 of an inch,by a tight drum of planking called the apron. This prevents the water fromspilling freely out of the buckets as they descend. To transform this intoan overshot wheel it would only be necessary to remove the apron, reversethe direction of the floats and carry the water over the summit. The overshotwheel did not usually have an apron, as that forces the water to leave thewheel in the same direction as it approaches. both the overshot and breastwheel ran at a speed much in excess of what would be considered economicalin modern practice.

The undershot wheel in common use for grist mills, the floats being radial,the arms are forked on the shrouding. The floats are set in dovetail groovescut in the shrouding and confined with keys, the expectation being thatthey would yield instead of breaking when foreign matter was caught betweenthe float and the sill of the race. The whole structure is evidently madelight and elastic with the view. The floats moved with a velocity abouttwo thirds that due the head of water, instead of half, which is all thatmodern views of hydraulics would allow.

These wheels never required more than two sets of arms. They were nevergeared to more than two run of stones, and the width required was from 2to 6 feet.

The counter gearing was the style of gearing in use for two run of millstonesis the "big face wheel" which gears with the two "wallowers."On the same shaft with the wallower is the "little face wheel."This gears with the "trundle," which is attached to the spindleof the millstones. The velocity of millstones was about 100 turns per minutefor a 5 foot stone, more for a smaller stone, less for a larger, a roughrule being to give the circumference of the stone a velocity of 1,500 feetper minute. The gudgeon of the wallower shaft, next the main shaft, restedon a sliding block, which enabled the wallower to be drawn out of engagementwith the big face gear, leaving one stone idle. It will surprise some readersto learn that gudgeons of horizontal shafts ran on stone bearings. OliverEvans gives directions for the selection of these stones: "hard andfree from grit." He also enjoins great care, to prevent the heatingof gudgeons, as it is liable to crack the stone on which they run.

Another wheel much used for grist mills, viz, the tub wheel, so calledbecause it ran within a circular enclosure of thick planking put togetherin the form of a tub, without bottom. It runs upon a vertical shaft, and,with a head sufficient to give the necessary velocity, drives the stonewithout the intervention of gearing. More commonly a spur gear and trundlewere used as drive the millstones. The wheel is 7 feet external diameter,with a head of 10 to 12 feet. The floats are radial and are fastened tostarts inserted in the shrouding pieces by means of dovetail tenons andkeys. The water was let on through a spout leading from the flume to thewheel.

A wheel of this construction was running at Lowell machine shop some 30years ago, and isolated specimens are still extant in old mills. Sometimesthe circular rim was made lighter and attached to the floats forming a partof the wheel and revolving with it. Often the floats were set in an inclinedposition, more nearly perpendicular to the direction of the water issuingfrom the spout. Ordinarily a small wooden pipe was inserted in the top ofthe spout close to the flume, reaching to some height. The precaution wasnecessary, to prevent the collapsing of the spout on the sudden closingof the gate from the partial vacuum created by the momentum of water.

A flutter wheel was simply a tub wheel without the rim, or perhaps moreproperly, a tub wheel without the tub. Two examples of this form of wheelwas used in saw mills, which was their principle application. The wheelused for giving motion to the saw. This had to be small diameter in orderto give, under any ordinary head, the required speed of about 120 strokesper minute to the saw. The body of the wheel is represented as a solid pieceof 27 inches in diameter. At one end a gudgeon in inserted, at the otherend a crank for giving a reciprocating motion to the saw frame, by meansof a long wooden rod called the pit man. The floats are secured in forkedstarts set in the body of the wheel by dovetail tenons and keys. The weightof the water was considered advantageous as giving a more equable motionto the saw. The water was let on from an opening at the bottom of the flume.Another arrangement of sluice for applying the water, allowing it to falldown an inclined chute through a gate opening formed to give it the properinitial direction. An old method of lifting and dropping a gate, the agatestem passed through a guide. A chain for lifting the gate was attached ata point near the top. The chains pass in opposite directions around a drumand are fastened at the back. the operation of the gate by means of thelever is obvious.

The flutter wheel used in a saw mill for running back the carriage. It is4 1/2 feet in diameter to the extremity of the floats. Its constructionis the same as that of the tub wheel already described, except that theshaft is squared where the arms on, and the latter are applied.

The mechanism of the primitive saw mill now as much an antiquity as theold domestic spinning wheel. In the water wheel powered saw mill using aflutter wheel, the saw stretched in its frame, ran in grooves in the fenderposts. These were attached by hook tenons to the beams of the mill and wereadjustable laterally by wedges. The carriage which supports the log it runsupon the ways consisting of narrow plank set edgewise in notches by a trundleon the same shaft with the rag wheel. This wheel has an iron ratchet ringin its periphery, and is provided with teeth in the manner of a face wheel.The vertical shaft of the flutter wheel carries at its upper end a lanternwhich remains in gear with the face wheel, the flutter wheel conformingto the movements of the carriage. A series of teeth is inserted in the bottomof one of the side timbers of the carriage frame. They are alternately onopposite sides of the way on which it run and fit the latter closely. Theway is interrupted at the point where the trundle engages with these teeth.A lever worked by the top of the saw frame imparts a rocking movement toa shaft with a projecting arm to which the hand pole is jointed. This polecarries an iron "hand" at its opposite end resting on the ragwheel. This wheel is provided with a pawl which prevents it from going backward,advances the carriage slightly at each stroke of the saw. The hand poleis attached to the arm by a pin, and by means of a series of holes in thearm the feed can be varied according to necessarily. One end of the logrests upon the head block, fixed upon the carriage, the other on the tailblock which is adjustable to suit the length of the log. "Dogs,"attached to the blocks, are driven into the log to hold it in position.When the tail block closely approaches the saw, a projection on the carriagestrikes a trigger which lifts the hand pole and pawl off the rag wheel,turns a light stream of water on the flutter wheel and the carriage runsgently back till the saw, which does not stop, enters the recess in thehead block. The attendant then releases the dogs, adjusts the log with hismill bar to a new position, drives the dogs, drops the hand pole, and thework goes on.

There are several forms which the breast wheel assumed early in the presentcentury when textile manufactures began to extend. It was at a later datethat iron shafts were introduced. In this form many specimens still survive,though no new ones are constructed. It was not far from 1845, that the breastwheel in New England began to be replaced by turbines, and as the substitutionis not yet complete, it is apparent that the wheel must possess merit inorder to hold its ground so long.

In this form the wheel has a width, or as we should say, length, greatlyexceeding the old grist mill wheels, the one wheel being something over20 feet long. It has four sets of arms and shrouding. The shrouding at oneend is made much heavier than the others, and on this is bolted a seriesof segments forming a toothed ring through which the power is transmittedto a pinion called a jack gear. The arms radiate from cast iron hubs ordiscs fixed upon the shaft. The larger ends of the arms enter recesses inthe hub and are strongly secured by hard wood wedges, then covered by aplate united to the disc by bolts and nuts. The soling is secured to theshrouding by wood screws or lag screws. The buckets differ from the olderform of wheel in being made on two parts - the start, which is radial tothe wheel, and the float, which is usually in a direction nearly tangentto the soling. This bucket does not empty so soon as the older form. Inthe construction the floats and starts can be inserted in grooves cut inthe shrouding, the soling being applied afterwards. In that the soling isput in first, forming a continuous drum or barrel before inserting the buckets.

The admission of water is controlled by horizontal sliding gates, the wheelhaving three sets of three gates each. Each gate is attached by two rodsto arms on the rocking shaft, which is controlled by a regular in the mannerindicated. In wheel of more recent construction, the method of admittingthe water is employed, a heavy web of rubber cloth or leather is wound uponthe iron cylinder and uncovering the orifices according the the requirementsof the work. This method, however, does not appear to offer any advantagesover the old arrangement of sliding gates. On the contrary, the latter appearsto offer more ready adjustment of the velocity to sudden variations of power.

Ancient Gearing. - Large face wheels were made of two thicknessesof 4 inch plank, each wheel requiring 12 pieces called "cants."The pieces were all circled to the proper radius. Six of them were scribed,halved and pinned together into a continuous ring; the remaining six werebutted together, forming another ring; which was confined to the formerby a great number of wooden trenails. A face, some 6 inches wide and projecting1/2 inch. was formed on this later ring, in which teeth were inserted. Aset of arms was inserted in the shaft as already described for water wheels.To these the wheel was adjusted by suitable notches and shoulder and securedby pins.

The lantern was formed of two discs united by the rounds which served asteeth. Each disc was made of two thickness of plank or boards pinned togetherand strongly banded. These wheels were attached to their shafts or spindlesby wedges.

The Construction of the Spur Gear. - This is gathered from descriptionsof old gearing. A series of thick wooden staves or segments is bound togetherby iron hoops at the ends, leaving the central part free for the mortisesin which the teeth are inserted. The segments are cut with the grain parallelto the axis of the wheel The wheel thus formed is mounted on the arms inthe manner indicated. A mode of constructing large spur wheels more commonin Europe was the following; two sets of arms were mounted upon a squareshaft in the manner of a clasp arm. To these were applied shrouding pieces,as in the case of the water wheel, forming two rims at a suitable distanceapart. Between these rims was inserted a series of segmental blocks, thegrain radial, a tooth being formed on the outer end of each block. The wholewas firmly bound together with bolts and straps.

Old time water powered grist mill, though not comprehended in the titleof this paper, will be of interest in this connection. It is borrowed fromFairbairn"s "Useful Information for Engineers," and representsa corn mill erected in England in 1730. It is said by Mr. Fairbairn to correctlyrepresent the state of art with reference to mill gearing at that time.It shows that our American millwrights were not much behind their fellowcraftsmen of England at that early date.

F. COLLINGWOOD, M. Am. Soc. C.E.- I would like to ask Mr. Frizell whetherhe has paid any attention to cast iron wheels? As a lad, I remember therewas a foundry near where I lived where a great many cast iron wheels weremade. That was in 1845.

Mr. FRIZELL.- Many turbines have been and still are made almost wholly ofcast iron. Some very efficient wheels are made in this manner. A preferablemethod, in my opinion, is, to make the floats and guides of wrought ironor steel. These are set up in the molds before casting, and on pouring inthe molten metal they become solidly united with the cast iron parts.

Mr. COLLINGWOOD.- I asked the question because it seemed to me that wasprobably the beginning of the introduction of the turbine, which has finallydisplaced the wheels that are described in this paper.

Mr. FRIZELL. - Water wheels wholly of cast iron are not now, and never havebeen, to my knowledge, made. I use the term "water wheel," now,in distinction from "turbine," to indicate a wheel running ona horizontal shaft, with a diameter nearly or quite equal to the fall, sometimesgreatly exceeding the latter, the water acting on the wheel mainly by gravity.Such wheels continued to be made after the substation of iron for wood inconstruction. The shaft, and what we might call the "hubs," thatis, the members which unite the radial arms with the shaft, called rosettesor centers, were of cast iron; the remaining parts of wrought iron or wood.Wheels of this construction still continues to be made in Europe. As lateas 1886, as elaborate German work, by Bach, was issued, devoted mainly tothese wheels.

One of the largest and most elaborate wheels of this class, made whollyof iron, was erected at Greenock, in Scotland, some time previous to 1850.It was some 70 feet in height. Its construction was similar to that of theColumbia bicycle, the weight of the water acting directly on the gears andproducing no torsional strain on the shaft. For aught I know, it may bestill in operation.

The extension of the iron industry, and the substitution of iron for timber,was not, as had been suggested, the sole cause of the replacing of thesewheel by turbines. Other reasons contribute largely to this result. Thesewheels were bulky and occupied valuable space. In our rigorous northernclimate they had to be housed in to protect them from frost. I imagine thata turbine 5 feet in diameter would furnish as much power as the enormousbreast wheel that I have just referred to. There was still another reasonof great force. These wheels revolved with a slow speed. The Greenock wheelreferred to would not probably make more than two revolutions per minute,and an ordinary 20 foot breast wheel not more than seven or eight. To bringthis speed up to the requirements of modern industry involved changes andtransformations consuming much power. So that although the old overshotand breast wheel might, and no doubt often did realize quite as large apercentage of the power of the water as the modern turbine, the losses incidentto the intermediate gearing made the net result materially less. When wereflect that, as compared with the great wheel at Greenock, a modern turbineof 5 feet diameter, would not only furnish the same power, but would runwith a speed of 200 or 300 revolutions a minute, we perceive the enormouspractical disadvantage under which the great wheel works.

For operations requiring a very slow movement, there is no question thatwater wheels may be made to use water with an efficiency quite equal tothat of the turbine, or even greater. The Sagebein wheel, invented in Europe,some 20 years ago, yielded by actual test, and under the hands of an experimenterno less distinguished than M. Tresca, an efficiency of 93%, a result neverequaled or closely approached by any turbine. This wheel had a diametermany times the fall, and revolved with a very low velocity, not more than4 feet per second at the circumference - this wholly unsuited to most modernrequirements.

There is one use to which a wheel of this kind may be applied in which itwill probably never be superseded by the turbine, viz, the raising of waterfor irrigation or other purposes. A wheel of large diameter working on avery low head, too low to be available for a turbine, is provided with aseries of small vessels, which fill when at the lowest point and at thesummit of the wheel, discharge into a spout leading to the irrigation ditches.Many such wheels are found in great numbers in India, China, Southern Italyand Spain. Being used exclusively in hot countries, they require no protectionfrom the frost. It is said that more water is raised by this means thanby any other device known to man.

T. C. CLARKE, M. Am. Soc. C.E. - I remember seeing the old fashioned wheels.It may be of interest to call the attention of the Society to the reason,which I do not see given in this paper, why all these wheels have gone outof date and have been superseded by the turbine. It is because the age ofiron had suppressed the age of wood. In the old days they made what theycould in wood; the facilities of the country in working in iron were notsufficient to make the modern turbine, even if it had been invented. Afterthe invention of modern machinery the wooden wheels were superseded by iron,just as you have seen the iron plows take the place of wooden plows on thefarm.

Mr. CLARKE. - That confirms the view which I suggested. It would be impossibleto make a turbine or Pelton wheel out of wood; you have got to learn howto work the iron before you can make these modern wheels at all.

JOSEPH T. DODGE, M. Am. Soc. C. E. - This being the first time I have happenedto attend a meeting here I feel a certain embarrassment about making anyremarks, but I remember the use of a wheel with cast iron curved bucketsplaced inside of a rim, which was used specially to run the carriage backwhere they were sawing lumber. The spout conveyed water down at an angleof about 45 degrees, striking the curved buckets at a right angle as nearlyas possible. Those curved buckets were supported by an outer and an innerrim. The overshot and undershot wheels were also in use, as has been described.That, of course, refers to the time between 1830 and 1840. I recall howthe wheel was propelled in one saw mill. The saw was an up and down one;the wheel consisted of two rims with straight floats between; the waterwas delivered at an angle of 45 degrees, striking the flat faces and workingthe crank which operated the saw. That is the way the country saw millswere operated. The overshot was used too, in some cases.

O.F. NICHOLS, M. Am. Soc. C.E. - The Burden overshot wheel at Troy, whichhas, I think, been mentioned, should rank among the old American wheels.IT was constructed of metal, and its diameter was very great about 60 feet.The conditions under which it was used are still maintained, and the wheelis now in use. These conditions were very peculiar. There was a comparativelyslight flow of water reaching the site of the wheel through the tail race,and falling 60 feet over the wheel. This was an uncertain flow, reliablewhen you could have it, but you could not always have it, and at very lowstages of the river every drop of the water was allowed to pass over thewheel. The wheel was 22 feet wide on the face. It had 36 buckets, each 6feet deep, and, of course, every time it turned around there was a greatdeal of work done with a relatively small amount of water.

Mr. Frizell has spoken about the necessity of housing in; as to the spaceoccupied by this Troy wheel, the wheel was placed in a niche or cranny ofthe rock that could hardly be used for any other purpose. They simply housedin a corner in the rock in which this wheel was placed. I doubt if the spacecould have been as well utilized in any other way. Working under a continuoussupply of water, efficiency of this wheel would be very great indeed, perhapssurpassing that of some of the modern turbines. The burden Iron Companyadvise me that the wheel was built in 1851, is still in operation and israted at 200 horse power.

The turbine wheels of modern times are among the most efficient of primemovers, and skill and ingenuity have so developed and improved these machinesthat they have been introduced to the exclusion almost of all the otherforms which utilize peculiar surroundings, as at Troy. The modern wheelis compact and convenient; you can use several smaller wheels in the samespace occupied by one large one.

I recall an instance in ordinary railway experience where it was desirableto furnish the power for drills, etc., in tunnel boring, and where it wouldhave been very difficult to obtain or set up steam apparatus or indeed anymachinery, and very expensive to transport it to the tunnel sites. In oneor two instances we arranged to use a large overshot wheel. The reason forselecting this character of wheel was that, having a pretty good grade inthe river, a mountain torrent, we could use a closed tube under very lightpressure, carried at very light grade, about one half of one per cent. Thiswas enough to carry the water along the bank of the river, and then we simplyextended this pipe or tube until we had reached the level of the top ofthe wheel. The wheel was made in sections and could be moved from one placeto another and had no expensive foundations. A turbine wheel in such caseswould be out of the question. I wish Mr. Frizell had given us some instancesand illustrations of the more celebrated of the older wheels. I know thatthe wheels he speaks of in Europe have been illustrated, and I wish theTroy wheel might have been pictures, and its efficiency, present conditionand relative usefulness made know; it was certainly one of the older ofthe powerful American wheels, and the forerunner of the more compact butnot more efficient turbine.

Mr. LEVALLE. - I hope I do not impose on the kindness of the members. InFrance, especially on the Seine, where the current is very rapid, they havelarge wheels made like those of a steamboat; these are in the front. Thepaddles are very long and instead of moving the boat, the boat is anchoredand the wheel is let loose and it is moved simply by the velocity of thecurrent, and this is utilized for small industries, for turning a lathe,or for grinding coffee, or probably chicory or whatever goes into the coffee.I do not know whether these have come to the knowledge of Mr. Frizell. Ithink it would be interesting to know. I think they would be of value tosmall industries. I do not suppose they could be applied in this countryto large industries.

Mr. COLLINGWOOD. - In reference to those wheels, I saw a great many of themin going down the Danube; these were quantities of those wheels. I thinkthey were used for all milling purposes, I think for grinding corn.

A. McC. PARKER, M. Am. Soc. C.E. - I have seen water wheel much of thatpattern used in Colorado for irrigating purposed. A wheel was put in a streamso it could turn, and as it turned it had boxes on the outside of it, eachof which took up a small amount of water which was thrown into a flume andused for irrigating purposes.

L. L TURNER, Assoc. M. Am. Soc. C.E. - I remember an instance of what mightbe called an automatic water wheel running a small saw mill which I cameacross in a small stream high up in a Swiss mountain district. I was curious,also wanting to rest, so went into the saw mill, but could find no one operatingit. There was, however, a vertical saw industriousl