I own this blog

New series starting on Imagineering.blogspot.com

mind power

Is it worth the time

The time to set up the time to write articles it apears that no one reads I am thinking that the effort to continue is usless will give it another go for six months Went to Tasmania for a working holiday with out pay well, I was rediculed by the owner of the property I drove a tractor the first day cutting grass in 30 degree temperatures. The second day was cutting fire wood with an axe in high temperatures wich I enjoyed and the third day was the first and last straw. I did not try to split wood with knots in it as this wood does not split well . They had an open fire place that these pieces would fit into easily.I was attacked for not splitting the knotty wood, verbally and my man hood was even a target . I walked back to my tent and packed my napsack and walked with out saying anything. I was picked up by a contractor carpenter and taken 40 kilometers to town. So the morell of the story is :- Free hands are always busy.

Nothing has changed

Looking back it is all the same with the names changing faster than a revolving door ...

To good to be bad too bad to be good.

 When you think you know how to live in society the rules change.

As a child the rage was buck teeth and I had them with all the name calling it was the worst, Then came the day when I accidently knocked them out the front top teeth. and all the teeth went back in my face I just had too many teeth. Bliss for some years. 

Then came the aborigine colour thing Too black to be white and too white to be black, Boy did the family have a field day with this one, Have not spoken to them since my mother died and my father died on you guessed it on my birthday. No more birth days but I think we really have one anyway. So I don't know how old I am. I don't care.

I am judged by a white mans admirative court and found guilty, Want to go to court sign here now you are guilty but you can have a day in court, GUILTY did I miss something here? Yep certainly did you go figure out you are the smart ones. HAHAHA. Funny 'A'

So the black bastard thinks he knows ( that's me) Well somebody in America calls out wolf in a big way but yells Out COVID-19! NOW THIS IS LIKE YELLING OUT FIRE IN A CINIMA. But this is worse. I think his name is Dr. Josef Mengele or is that Dr Anthony Fauci who cares.

Now we have this imaginary disease going to kill the world with true life Dr. Fannkinstine. You people are so predictable. "We are all going to die ". Yep no one is going to get out of this living thing alive.

I for one maybe thinks death is the real life.

I joined a couple of clubs paid up for five years went to go in last night to meet a friend not on your nelly you have no proof of being inoculated, talk about taking money under false pretences. Now that was a wasted effort with out true justice or is that "just ice". Can I have that with whisky.

Was at the local hardware store "Hammer Barn" and there was a little girl a she looked a me and screamed. Because I had a face mask on, phuck I did not think I could do that must be a gift!

There it is the true story of my life in nine paragraphs who needs a expensive book deal.

Australia the great nation

I haven't written much about the political scene here lately. The government has changed and the people in power are getting set to run the country. What a mess was left for them, the old government did what they could do to sabotage the economy to make the new government look bad in there first year.

New blog

New blog is now at http://nrma.blogspot.com.au/

The right to bare arms

This right will be taken away from us. We will have the right to fly models and I would encourage all the people to have a hobby.  Being an old fart with times changing one must look inward for entertainment and happiness. It is your responsibility to enjoy life and look after ones family first.Grand supper funds will not make you happy in old age and don't be conned into this falicy of old age and insurance. It is up to ones self to look after ones health and happiness. Friends and neighbors are your best insurance policies you will ever have. This was proven to me in the floods of March of 2012 and the only help was from friends and family. To date no money or help have come from government or insurance policies. My knowledge from my hobbies is what have helped me cope and to repair my life.

New order

The "piece of work" will be thrown out like the whore she is dumped in the streets like an old prostitute. Gone and forgotten like a legless drunk. Yes used and abused.Yes the first and the last female custodian of this state. Australia.

money and power

Money and power does not make a man or woman, Being a man or woman comes from dedication and ability. Australia has no true leaders or orators. Greed and power is what our leaders are after, This is shown by the begging to become a member of the united nations. True leaders would start there own Asia Pacific united nations and then rule the world.. with ability and charm. These are things lacking in our society. We are now a target for fanatics because of the US militarization of OUR country in the Darwin and Pine Gap areas. Allowing such bases spreads the war machine to OUR country. Yes Australia has been invaded. We will now supply uranium to India bringing atomic war closer to OUR shores all because of the "piece of work" in Canberra. Political assassinations may become a sign of the times in this once peaceful country. Yes we are now the fifty first state. Yes we are now unofficially the fifty first state so we under the constitution have the right to bear arms. This automatically makes us a member of the United Nations.

New prime minister for Australia.

Nicola Roxin is to challenge for the prime ministers job. She will challenge a piece of work!

why worry

Why worry about Tomorrow and Armageddon because you might get whacked today!

Revenge

I experienced this first hand, Revenge. This is an amazing story of revenge that I wanted and want it I did. This is a emotion that I never want to experience again because it is negative and destructive. When these emotions take hold they sway reality to the extreme with great passion. My experience was a lesson that I was to experience to the enth degree.
This is how it happened and to my amazement it took hold in a split second, I was closing the door of the shed in the rain and this small piece of timber slid down the wall and wacked me on the toe. Instant pain took hold and the mind took me to want to kill the wood then to my astonishment my mind told me I was being stupid and the timber was already dead then I said im glad. What and where this came from I do not know but all in a micro second. .

New site with photos

My sites have been attacked and the problems are happening faster than I can fix them so a new site has been opened at http://footrotflat.wordpress.com

Yowie , Kangaroo valley panther or imagination

I was a scout leader and was camping with a group of cubs at Kangaroo valley south of Sydney. We decided to play a few tricks on the group of kids and we had a big claw made from steel on a long handle. There was also a large footprint made as well also on a long handle. While the other leader was doing camp inspections and breakfast duties with the group I made my way down to the river and on the way scratched the bark on various trees along the track at the river footprints were made in the sand while keeping up on the river bank. The scratchings were about twelve to fourteen feet from the ground and the footprints were spaced about five feet apart. I secretly put the tools of deception away. Then came the fun part, TRACKING, the group was told to look for tracks of the local wild animals. This was to get a badge. Then one of the more astute boys noticed the scratching in the tree and asked what could it be was asked.  I reached up and they were about two feet out of my reach then came the punch line "it was the infamous kangaroo valley panther that no one had ever seen! Now the adrenalin was flowing. I lead them on down to the river and then stopped in my tracks and stood still they all followed suit. What are you looking at I was asked and the reply came quite!! The silence was deafening and there over there and I ran to the river bank followed by the group. Again one of the group saw the foot prints and pointed then out to the rest of them. The funny thing is from then on they never wanderered off on there own. Back to the foot prints I paced them out and the were about a foot longer in stride than I could make. This thing must have been huge about as big as a horse. The excitement grew with there imaginations getting the better of them enlarged the beast and the stories of men eating tigers and the like were spreading like a wild fire threw the group. That night we had finished tea and it was then stories around the camp fire. During one of those moments where all conversations seem to cease and silence is golden a cow in the field let out this almighty bellow MOOOOOO. Not expecting what was to follow this little guy jumps up from the other side of the ring of kids and ran as fast as his little legs could carry him and darts under my left arm and says you can look after me wont you sir!? Yes I says and the conversations went on into the night. Back a the scout hall a week later the leaders myself included were asked as to what went on at the camp as all the kids had night mares for the following week. We were forced to reveal our hand and the tools of deception and not one of those kids would admit that they were conned and all said they knew and were going along to keep the leaders happy.

National parks and the water authorities

I was walking in the bush in a controlled area that is it is gated to stop the common trash entering the area. I walked deep into the area and low and behold trash dumped in the bush by whom you might ask.
If I was going to dump rubbish then I would have dumped it at the gate, not carry it two kilometers into the gated area and so would any normal person.
It appears to be the ones with the keys to the locks are dumping the rubbish. The custodians of the lands and the animals. We the people are being forced from the lands by greedy self serving officials with there own agenda. The question is what is really there agenda, the law states that persons squatting on the lands for more than twenty five years get to keep it. These payed positions are given to you guessed it politicians and there families and they will own the land and then there is nothing that can be done.
So the thing to do is enter these areas and keep the land in the public domain.

Protect your fairy doors and fairies

It has come to my attention that Roosters will chase and eat fairies. Please make sure that they are fenced in to protect your fairies. This little roster was Soo protective of his owners and had to be sent on a long journey never to return home.
The little girl in the sacred forrest told me.

Fairy condimiumn

This shows a fairy condomiumn near the house they only live in these for one year and then move out and go north for the winter and return the following year The goblins make them for the fairies.

Can anyone please tell me how to fix the stripes on the photos on blogger upload? cheers Iggle

If you left one of these comments do not read my blogs

Forest Service Feedback

These quotations are actual comments left on Forest Service registration sheets and comment cards by hikers completing wilderness camping trips.

---

• "Escalators would help on steep uphill sections."
• "A small deer came into my camp and stole my bag of pickles. Is there a way I can get reimbursed? Please call."
• "Instead of a permit system or regulations, the Forest Service needs to reduce worldwide population growth to limit the number of visitors to wilderness."
• "Trails need to be wider so people can walk while holding hands."
• "Ban walking sticks in wilderness. Hikers that use walking sticks are more likely to chase animals."
• "All the mile markers are missing this year."
• "Found a smoldering cigarette left by a horse."
• "Trails need to be reconstructed. Please avoid building trails that go uphill."
• "Too many bugs and leeches and spiders and spider webs. Please spray the wilderness to rid the area of these pests."
• "Please pave the trails so they can be plowed of snow in the winter."
• "Chairlifts need to be in some places so that we can get to wonderful views without having to hike to them."
• "The coyotes made too much noise last night and kept me awake. Please eradicate these annoying animals."
• "Reflectors need to be placed on trees every 50 feet so people can hike at night with flashlights."
• "A McDonald's would be nice at the trailhead."
• "The places where trails do not exist are not well marked."
• "Too many rocks in the mountains."
• "Need more signs to keep area pristine."

boat mills

http://www.lowtechmagazine.com/2010/11/boat-mills-bridge-mills-and-hanging-mills.html

November 16, 2010

Boat mills: water powered, floating factories

The waterwheel was seen as the most important power source in the world, from the Middle Ages to the end of the nineteenth century. When smaller streams became saturated, medieval engineers turned their attention to larger rivers, eventually leading to the development of the hydropower dams that still exists today. Lesser known are the intermediate steps toward that technology: boat mills, bridge mills and hanging mills. Boat mills had already appeared in 6th century Italy and spread all over the world. Most of them remained in use up until the end of the 1800s, with some of them surviving well into the 1900s.

Picture above: Last ship mill on the Rhine, 1925

Until recently, "boat mills", also known as "ship mills" or "floating mills", were largely thought of as a curiosity, a mere footnote in the long history of water power technology. Today some historians think that they were almost as widespread as windmills - although it should be noted that windmills, contrary to popular belief, were less common than watermills. The first monographs of boat mills only appeared in 2003 and 2006 (see sources). They contain, among many other new facts, the discovery of three tiny ship mills on a famous medieval painting from 1435 ("Madonna of Chancellor Rodin" by the Flemish painter Jan van Eyck). Nobody had noted them before, or weren't cognisant of exactly what they were.

Boat mill, Encyclopédie Diderot, 1751

Granted, boat mills are curious things. Some look like paddle-wheel riverboats, but in fact they are exactly the opposite. A waterwheel can be used in two ways: to create energy from moving water, as is the case with the water mill, or to apply energy to water with the result of motion, as is the case with a paddle-wheel boat.

The boat mill has the outside appearance of the latter, but it works just like a water mill. Basically, a ship mill is a water mill (waterwheel + milling house) built on a floating platform, moored to the river bank or anchored in the stream. The flowing water turns the water wheel, which in its turn drives the milling machinery. Ship mills could be used as single units, or fastened together side by side. 

Advantages of ship mills

Why build floating water mills when you can just as well construct a fixed water mill on the bank of a river? There were several good reasons. Although water is a much more reliable power source than wind, you cannot always count on it. Rivers rise and fall with the seasons and with the prevailing weather, while the axle of the water wheel remains at a fixed height. On smaller streams this variability could easily be mitigated by creating a small dam and sluice gates, forming a mill pond to even out natural flow conditions. An overshot wheel could also be used, especially in hilly regions. This wheel receives water from above via some kind of aqueduct and is more efficient (50 to 65%) than an undershot wheel (20 to 30%).

However, constructing dams and sluice gates would be much more difficult to achieve on a stream 100 metres wide and 10 metres deep. Overshot wheels could not be used. Since the water level in many large rivers could vary substantially, a fixed watermill on the bank of a river could thus easily end up with its blades above the water, rendering it useless. Conversely, rising water levels could partly or completely submerge the wheel, again rendering it useless (contrary to a modern turbine, which can operate fully submerged).

Ship mill on the Mura in Slovenia, source.

Even less extreme variations of the water level could seriously decrease the efficiency of a fixed water wheel. An undershot wheel derives its power entirely from the impulse of water, not complemented by gravity as is the case with an overshot wheel. In combination with a mill pond, the water could be directed at an optimal angle to the undershot wheel in order to obtain maximum efficiency. On a large river, where no mill pond was available, this was not possible - further decreasing the already limited efficiency of the undershot wheel.

Ship mills on the Seihun, Adana, Turkey, around 1920. Postcard collection Ton Meesters, Breda, the Netherlands

Floating watermills solved these problems. They simply followed the water level, keeping the undershot wheel always at a continuously ideal position. The result was a power source that was available 24 hours a day and 365 days per year (with the exception of extreme weather events). Furthermore, ship mills could be located at other parts of the stream where water velocity was higher than close to river banks, increasing their power output. Last but not least, ship mills also overcame the problem of overcrowded river banks, an especially important consideration for cities.

Two types of boat mills

 Basically, there were two main types of boat mills. One type was composed of two hulls with a water wheel in between, while the other type consisted of one hull with two waterwheels on both sides (or, sometimes, one waterwheel on one side). The boat mill with two hulls, somewhat resembling a catamaran, was by far the most efficient and powerful of both models. The two hulls channelled the water onto the wheel, increasing the impulse. A boat mill with a single hull did exactly the opposite.

Furthermore, the floating mill with two hulls (illustration on the right, by Johann Matthias Beyer) could support much larger wheels than the type with one hull (illustrations on the left, from the "Encyclopédie Diderot"), again increasing the power output. Thirdly, the double hull allowed for a system of control gates to regulate the amount of water hitting the wheel, thereby making it possible to better control the speed of the machinery inside the milling house, or to stop the wheel altogether. This system also protected the wheel against driftwood. Finally, a boat mill with two hulls was also more stable.

Construction plan

One of the hulls was much wider than the other one. It housed the millling machinery (mill stones and gears), the grain to be ground, and - in the case of larger ship mills - the boat miller residence. In the case of smaller ship mills, this house stood on the bank of the river. The smaller pontoon only served to carry the axle. The main hull and the pontoon were connected at the front and the rear with strong beams. Balancing the floating mill was done by loading stones in the pontoon.

The large hull was always on the side of the river bank for easy accessibility - this meant that ship mills with two hulls were designed with a specific location in mind: the left or the right bank of the river (on the aforementioned painting by Jan Van Eyck, this fact was overlooked by the artist). If it was moored on the river bank, the mill was accessible by a stone or wood bridge or gangway. Sometimes pack animals were used to deliver the grain and to take away the flour. If the boat mill was located midstream, it was only accessible via small boats.

Diversity

Boat mills, which were built almost entirely out of wood, could be impressive structures. Generally, they were 10 to 15 metres long, while the longest ship mills described measured 20 metres and more. The large hull was usually 5 to 8 metres wide, the pontoon 2 to 3 metres. Both were mostly built in a rectangular form. A ship mill could be more than 6 metres tall and some had two or even three floors.

However, while some floating mills were huge and outstandingly crafted, others were rather small and sometimes very crude contraptions. The life expectancy of a boat mill could be between 30 and 50 years, with the wheel itself lasting for a decade. But some ship mills did not last even that long, rotting from the inside or simply falling apart.

Two boat mills - one with balcony - on the Elbe in Aachen, Germany, 1899. Postcard collection Ton Meesters, Breda, the Netherlands

Huge wheels

While conventional water mill wheels were seldom wider than 1 metre, the wheels of ship mills with two hulls could be up to 6 metres wide, with the axle up to 10 metres long. Medieval engineers explored the limits - wooden wheels could not be built larger than this if they were to retain their strength. The huge wheels had a diameter of about 5 metres and turned at 3 to 5 revolutions per minute, depending on the velocity of the stream. They delivered between 3 and 5 horse power at the shaft.

Ship mill on the Kur in Tiflis, Georgia, around 1900. Postcard collection Ton Meesters, Breda, the Netherlands

Ship mills with one hull could not support these wide wheels and delivered much less power. Among the lesser common types of boat mills were those with two water wheels in between the main hull and the pontoon, allowing them to operate two mills at the same time. They required very long axles, which were not always easy to find (illustration below). Placing the two wheels one after the other resolved this, at the expense of decreased efficiency.

Uses of boat mills

From the 15th century onwards, many conventional water mills started performing tasks other than milling grain, but most boat mills did not. Almost all of them were corn mills. There were a few exceptions. Karel Broes, the Flemish author of the 2003 monograph, lists a few floating paper mills, sawmills, fulling mills, oil mills, polishing mills, minting mills and cotton mills. Some of the more recent ship mills ended their life as an energy source for power generation.

In his standard work on the history of Chinese technology, Joseph Needham cites a 16th century Chinese writer who describes trip hammers mounted on boat mills to make paper:

"In Liang-chiang there were many ship mills, which work on the same principle as the water raising wheels, and are all anchored in the rushing water. The operations of grinding, pounding, and shifting (bolting) are all carried out by the use of water power. The boats make a noise 'ya-ya, ya-ya' incessantly".

Diderot described a stationary tugboat (below).

Origins

Few inventions from Antiquity can be dated as precisely as the ship mill. In 536 or 537 AD the Goths besieged Rome. In an attempt to starve the Romans, they cut the 14 aqueducts that delivered water to the city. This did not deprive the Romans of drinking water because the Tiber flowed through the walled city. But the aqueducts were the power source for the water mills that ground the grain for the whole city.

However, the Byzantyne general Belisarius, then in charge of defending the city, came up with the luminous idea of the boat mill. The event was accounted for in detail by the contemporary author Procopius:

"When the water was cut off and the mills stopped, and cattle could not grind, the city was deprived of food, and provision could hardly be found for the horses. But Belisarius, an ingenious man, devised a remedy for the distress. Below the bridge across the Tiber he extended ropes, well-fastened across the river from bank to bank. To these he affixed two boats of equal size, two feet apart, at a spot where the current flowed with the greatest velocity under the arches; and placing mill-stones in one of the boats, he suspended machines by which they turned in the water-space between them. He also contrived, at certain intervals on the river, other machines of the like kind, and these being put into motion by the force of the water, drove as many mills as were necessary to grind food for the city."

Boat mills on the Tiber, Italy

After that, the Roman empire did not last much longer - the Goths took Rome in 562 - but the ship mill would remain in use for another 1,400 years, with the last one only disappearing in the 1990s. Remarkably, during all those centuries, boat mills hardly changed. Those that could still be seen during the second half of the 20th century looked very similar to those illustrated in the Middle Ages (no earlier images of ship mills have survived).

Distribution of ship mills in Europe

After its initial success in Rome, the ship mill became a common sight on the Tiber and quickly caught on all over Europe. During the 6th century they also appeared in Switzerland (Geneva) and France (Paris and Dijon). During the 800s, boat mills showed up on the Rhine in Strasbourg (France) and Mainz (Germany). At the end of the tenth century, they were noted on the Kur in Georgia. They reached Venice and the Balkans in the 1000s and Spain in the 1100s.

Ship mills on the Rhine, detail from "Ansicht von Köln" by Anton Woensam, 1531

Toulouse (France) had at least 60 ship mills on the Garonne in the 12th century, milling all the grain for the city. Paris counted 70 to 80 boat mills on a one mile stretch of the Seine in the 1300s. In 1493 there were 17 floating mills on the Rhône at Lyons, growing to 20 by 1516 and to 27 by 1817. The Elbe, flowing through Germany and the Czech Republic, once counted 500 boat mills. There were also hundreds of ship mills on the Danube: 62 in Vienna (Austria), 88 in Budapest (Hungary) and a non-specified amount in Slovakia, Croatia, Serbia, Bulgaria and Romania. The Mur, a river that flows mainly through Austria and Slovenia, had over 90 boat mills. Ship mills can even be seen on 17th century city plans of Moscow.

Ship mills on the Kur in Tiflis, Georgia, around 1900 (postcard from the collection of Ton Meesters, Breda, the Netherlands)

In her 2006 monograph, Daniela Gräf could find proof of almost 700 specific locations, mainly on the Seine, Loire, Garonne, Rhône, Rhine, Weser, Elbe, Oder, Danube, Po and their tributaries, on which one or more boat mills have existed at one time or another. The total amount remains unknown for now. Floating mills did not show up everywhere, though. The Scandinavians and the English never warmed up to the idea. Attempts to build them on the Thames in London failed twice in the 16th century and again in the 18th century. The reasons for this are not well known. In Flanders and in the Netherlands, boat mills never really gained popularity - not more than a dozen were operated from the 15th to the end of the 17th century. In this case the cause is clear: the flow of the rivers in the Low Countries is too low and water power in general was of limited use. Because the region had much better wind conditions, it became an important center of windmill technology.

Distribution of ship mills outside Europe

Boat mills appeared in the Islamic world at the end of the 9th century, where they were employed along the Tigris and Euphrates rivers. These large floating mills were equipped with four stones and could each produce around 10 tonnes of flour per 24 hours. Each mill could grind grain for around 25,000 people, which means around 60 of them were needed to feed the then estimated 1.5 million people in the Baghdad. Nothing yielding this scale of mechanised corn milling was known in any European country at that time, notes Terry Reynolds in his book on the history of the vertical water wheel (see sources). In 1148, Ibn Jubayr described the ship mills across the river Khabur in Upper Mesopotamia "forming, as it were, a dam".

Picture above: a cotton ship mill in Japan (1880-1933). Source: "water mills in Japan", Kenjiro Kawakami, Transactions TIMS, V, 1982

Joseph Needham found references of ship mills in Chinese literature in 737 (when "Ordinances of the Thang department of waterways forbid shipmills on the river and streams near Loyang as if they were something very well known"), 1170, 1313, 1570, 1628 and 1637. In 1848, traveller Robert Fortune found a whole colony of ship mills near Yenchow in northern Fukien. Here is his description:

"The stream was very rapid in many parts, so much that it is used for turning the waterwheels which grind and husk rice and other kinds of grain. At first I thought it was a steamboat, and was greatly surprised. A large barge or boat was firmly moored by stem and stern near the side of the river, in a part where the stream ran most rapidly. Two wheels, not unlike the paddles of a steamer, were placed at the sides of the boat, and connected with an axle which passed through it. The boat was tatched over to afford protection from the rain. As we got further up the river, we found that machines of this description were very common."

At the beginning of the twentieth century, Worcester made detailed engineering drawings of the ship mills still in action around the Chinese city of Fouchow. These carried four waterwheels on two axles - see the plan on the left.

Tide mills

Boat mills also opened up the possibility of generating power from coastal areas and estuaries, because they could be used as tide mills. The first one was described in 960 AD and was located on a canal of Basra in Southern Iraq. It could be that the early ship mills in Venice were tide mills, too, though nobody knows for sure. When a boat mill was used as a tide mill, its wheels would be pushed in one direction when the tide came in, and in the other direction when the tide went out. They could not be used for more than 10 hours per day. Very few of them were built - dams and tidal reservoirs were more common options to harvest tidal energy.

Bridge mills

Medieval millers quickly learned that the output of boat mills could be increased when they were anchored or moored close to islands, sand banks or man-made structures - most notably bridges. The wide piers and short arch spans of medieval bridges greatly increased the velocity of the stream at these locations. Positioning a ship mill underneath the arches of a bridge or just downstream from it became very popular practice during the Middle Ages. Reynolds notes that when the "Grand Pont", a masonry bridge in Paris under which more than a dozen ship mills were located, was destroyed at the end of the 13th century, it was the owners of the mills who quickly built another (wooden) bridge to facilitate the operation of their boat mills.

From this practice came the evolution of the bridge mill, which probably appeared in the 12th century (the first description comes from Cordoba, Spain). Bridge mills did not float - they were built as part of a bridge with the milling machinery built on top of the bridge itself. Unlike boat mills, they required some mechanism to alter the position of the wheel as the water level changed.

In most cases the mill was suspended from the bridge by chains which could be adjusted by a capstan arrangement (as described by Zonca, illustration on the left) or a treadmill. Bridge mills had sluice gates to control the flow of water and to protect the wheel against driftwood. From the 16th century onwards, quite a few ship mills were replaced by bridge mills.

Reconstruction drawing of the bridge mills at the Pont-Aux-Meuniers, Paris, 16th century. Source: "Paris à gré d'eau", Beaudoin Francois

Hydropower dams

The bridge mill was an intermediate step in the process of adapting the waterwheel to large rivers, culminating in the hydropower dam that we know today, as described by Terry Reynolds in his study on the history of the vertical water wheel (see sources):

"The hydropower dam and its adjunct, the power canal, presumably evolved from the boat mill and the bridge mill. The boat mill had been an attempt to adapt the vertical wheel to the natural flow of streams. The bridge mill had been a further step in that direction, but it had also demonstrated that natural conditions of flow could be significantly improved by human artifices. In one sense, the medieval river bridge, when combined with either boat or bridge mill, was a primitive form of hydropower dam, an intermediate step between the unassisted boat mill and the full-scale hydropower dam. Intentionally designed hydropower dams and the power canals frequently associated with them, however, went a step further. The boat mill and, to a lesser extent, the bridge mill had adapted the water wheel to natural stream conditions. The hydropower dam did the reverse. It adapted the stream to the water wheel."

Hanging mills

A variant of the bridge mill was the "hanging mill" or "suspended mill", which was not suspended from a bridge but from a specially designed structure (bridge mills are sometimes called hanging or suspended mills, too). It worked in a similar manner but did not offer all the advantages of the bridge mill - capital costs were higher and boats were required to access them. Their commonality was their relatively high power output, since they could support multiple waterwheels and could be built much larger than boat mills.

Less is known about these suspended mills, and most of the available data is limited to France (the "moulin pendant" above was located at Châtres and was still working in 1910). Three large hanging mills were built in Paris on the Seine during the 17th century. They took care of the water supply for the city, pumping water from the river.

The "Pompe du Samaritaine" was built in 1608 and the "Pompe du Pont Notre Dame" - which actually consisted of two suspended mills with a water tower in between - was built in 1670, following a severe water shortage. They had a power output of respectively 8.7 and 18.6 HP. The Pompe du Pont Notre Dame, which was demolished in the second half of the 19th century, is pictured above on a 1756 painting by J.B. Raguenet - note the floating mill just behind the bridge.

Large suspended mills (of a different type) were also built outside of France, notably in Germany (where they were called "Panstermühlen") from the 16th century onwards. Beyer describes one with multiple wheels that was 27 metres long, 15 metres wide and 18 metres high - see the illustration below. It was built on the river bank, but contrary to a conventional fixed water mill the wheels could be moved up and down. In the 19th century, yet another type of hanging mill appeared in Romania and Poland (the "Alvan").

Hanging mills were also built in the Far East from the 15th century onwards. In the Japanese mill below, which appears in Broes' monograph, the water axle was lifted by means of a lever construction.

Accidents waiting to happen

Bridge mills and hanging mills had another important advantage over floating mills: safety. Right from the beginning, ship mills caused problems. During heavy floods or storms their moorings often broke. The mills were carried away - sometimes with the people still inside - and smashed into boats, docks, bridges or other ship mills. They could get stuck in the arch of a bridge, damming the river and thus causing the waters to rise even higher. Floating ice could have similar consequences. Ship mills were not built with any means of proper navigation, so when they broke loose they were out of control. They could only navigate in calm weather.

Even under normal weather conditions boat mills formed a threat, especially for navigation. A floating mill required very secure anchoring, in order to avoid the accidents described above. Usually the method used was to hammer heavy wooden posts into the riverbed - often angled upstream - on which to fix their chains. These posts were a hazard to other boats, especially when the ship mill had been moved to another location in the meantime. 

Bridge mills and hanging mills did not pose these risks. Furthermore, their wheels could be taken out of the water when there were floods or ice, preventing damage to the mill. They were also more stable - another drawback to ship mills was that they sometimes delivered a product of inferior quality, due to the instability of the water. This might explain why most ship mills were only used to grind grain. Finally, bridge mills and hanging mills were also easier to maintain than boat mills.

The demise of the ship mill

In some regions boat mills were discontinued rather quickly. The 60 floating mills that were installed in Toulouse in the 12th century had disappeared less than a century later. They were replaced by three dams on which 43 fixed watermills were erected. The largest of these was the 400 metres long diagonal Bazacle dam, which was in operation by 1177 and remained the largest hydropower plant for quite some time.

The last ship mill on the Elbe in the Czech Republic

However, this drastic and early transition seems to have been an exception rather than the norm. Many more hydropower dams were built, and more boat mills were replaced by bridge mills or hanging mills, but in most European countries and in the near East ship mills remained in use well into the 1800s.

The majority of boat mills were discontinued between 1770 and 1870, which is no coincidence. Around 1780, the first steam river boats appeared and river navigation became ever more important. The use of ship mills was restricted by law in Austria in 1770 and in Paris in 1787. The construction of new ship mills was outlawed on the Rhine in 1868. In response to strict regulations in Slovakia at the end of the 19th century some boat mills were converted to fixed water mills on stilts - yet another variation (picture below, by Leo van der Drift).

In Paris, only 4 ship mills were left in 1800. The last boat mills on the Seine, the Loire and the Rhône disappeared respectively in 1840, 1842 and 1894. The last ship mill in Cologne was discontinued in 1847. At the beginning of the 1800s, there were still about 20 ship mills active on the Tiber, milling grain for a population of 158,000. At the end of the century, the last one disappeared. On the other hand, Vienna (Austria) still had 55 ship mills in 1870. In China they were used up to the end of the 19th century.

Boat mills in the 20th century

On some rivers boat mills could still be seen in the 1900s. During the first half of the century, working boat mills could be found in Georgia (Tiflis, 9 mills operating in 1909), Czech Republic (Lovosice, 1911), France (on the river Doubs, 3 mills operating in 1914), Iraq (Tekhrit, where they were used at least until 1917), Italy (10 boat mills in Verona in 1914, the last one stopped working in 1929), Turkey (1920), Germany (several locations, until 1926), Japan (1933), Slovakia (1937), Hungary (Tiszán, 1940) and Austria (Misseldorf, until 1945).

Bosnia had 27 mills left in 1950 with the last one disappeared in 1966. In Romania, 35 ship mills were still in use in 1957, and 8 of these were still working in 1968. Finally, the French historian Claude Rivet found a working ship mill on the Morava at Kuklijn (Serbia) in 1990, which was discontinued shortly afterwards. This seems to have been one of the last working authentic boat mills (check out this interesting video). Since then, around a dozen reconstructions have been built.

Kris De Decker (edited by Shameez Joubert)

Ship mill in Serbia, 1990. Picture by Claude Rivals.

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Sources (in order of importance):

• "Over schipmolens en andere onderslagmolens met in hoogte verstelbare wateras", Karel Broes, Molenecho's, Vlaams tijdschrift voor Molinologie, July - September 2003. There seems to be only one (more or less) publicly accessible copy of this issue, in a library in Antwerp, Belgium. 
  
•  "Stronger than a Hundred Men: A History of the Vertical Water Wheel (Johns Hopkins Studies in the History of Technology) ", Terry S. Reynolds, 1983. Here's where I got the idea. There is no detailed information to be found on boat mills, but Reynolds puts the technology in its context.
• "Boat mills in Europe from early medieval to modern times", Daniela Gräf, 2006. I could not obtain a copy of this book yet, so I relied on some reviews and the table of contents. It is based on a thesis written in 2003, and must be a valuable addition to the sources mentioned above.
• "Wheels ex-aqueous and ad-aqueous; ship-mill and paddle-boat in east and west", in "Science and Civilisation in China, Vol. 4: Physics and Physical Technology, Part 3: Civil Engineering and Nautics", Joseph Needham, 1971. Ship mills in Asia.
• "Theatrum Machinarum Molarium, Oder Schau-Platz der Mühlen-Bau-Kunst", Johann Matthias Beyer, 1735.
• "Vollständige Mühlen-Baukunst", Leonhard Christoph Sturm, 1718.
• "Die Kölner Rheinmühlen I & II", Horst Kranz, 1991-1993. There is also a website.
• "Studies in Ancient technology", R.J Forbes, 1965
• "L'Encyclopédie", Diderot et Alembert, 1751
• "Histoire d'une technique. Le dernier moulin à nef", Claude Rivals, L'Histoire, nr.153, 1992
• "Le moulin et le meunier. Mille ans de meunerie en France et en l'Europe", Claude Rivals (2000).
• "Paris à gré d'eau", Beaudoin Francois, 1993
• "Schiffmühle", wikipedia.
• "Wind, Water, Work: Ancient And Medieval Milling Technology (Technology and Change in History)", Adam Lucas, 2005
• "A survey of water mills in Japan", Kenjiro Kawakami, 1982

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