MAGAZINE SOBRE HISTÒRIA (Iniciat com AUCA satírica el 1960.. per Manel Capdevila a classe de F.E.N.)
-VINCIT OMNIA VERITAS -
"La història l'escriu qui guanya".. així.. "El poble que no coneix la seva història... es veurà obligat a repetir-la.."
|10-06-2014 (1552 lectures)||Categoria: Leonardo|
Unlike other possible unrecognized transmissions from classical times this one got a lot of public debate. Some saw it as unbelievable and called it a modern fraud. The public dispute went beyond academic custom and created some bitterness. A careful new look on the subject seems overdue.
The bicycle sketch is drawn on the backside of folio 133 ("133verso") in the Codex Atlanticus. By later analysis it was found that folio 133 and 132 were originally one sheet and folded together for some time after the bicycle and graffiti drawings. Pompeo Leoni (1533-1608) created Codex Atlanticus of about 1300 sheets of Leonardos work. Had Leonardo only used the front side the sheets were glued with its backside in the codex. Otherwise Leoni had cut a window in the carrier paper. But the bike got no window and was covered for centuries.
Since 1636 the codex stayed with the Bibliotheca Ambrosiana of Milan. From 1966 to 1969 the Ambrosiana gave the codex for restoration to the "Laboratorio di Restauro" of Grottaferrata. Because the Ambrosian Library belong to the Vatican the archbishop of Milan requested the work be done by the monks of cloister Grottaferrata near Rome.
The contract included the clause that "no person was to be admitted to see the folios of the Codex during the years of the restoration". Tasked with the transcription of Leonardo's writing the historian and philologist Augusto Marinoni (1911-1997) had only access to photographys taken by the Bibliotheca Ambrosiana after the return of the Codex.
Based on the restoration in 1974 a facsimile edition of the codex and a book "The Unknown Leonardo" was published. The later covered the 1967 found Codex Madrid too. Both publications had facsimiles of the bicycle. The bicycle sketch was first presented to the public in a lecture by Augusto Marinoni in spring 1974. Marinoni actually found it on the photography and no report by the monks of Grottaferrata is published yet.
At least part of the sketch was found before the restoration in 1961 by the art historian Carlo Pedretti of UCLA. In his 1978 book about the codex he wrote:
He included a sketch from memory of what he saw in 1961. His original notes were stolen with his car in 1965. Pedretti claims he saw two circles with curved lines bisecting them but not a whole bicycle sketch. He thinks the sketch and the graffiti were probably not from Leonardo‚Äôs time. After the news in 1974 he stated "Folios 132 and 133 hardly deserve the attention they have received". But by the importance of the subject and the forgery accusations it is unfortunate they got not the attention they deserved.
The sketch Pedretti presented 1978 as drawn from memory fit perfect on the original bicycle sketch. So it was only a redraw of parts of it. He did not address the problem that in translucent light the central parts of the bicycle were covered by the fortification drawing from the other side. That he had to look through three sheets (F133, the carrier, F132) of which four pages had drawings. To identify something totally unexpected in such a chaos was hardly possible. The lines he noted were already a good recognition work. Pedretti gave no explanation how the "scribbles" could be from later time when the original sheet they covered was cut in two certainly before 1608.
An early argument against authenticity was the very modern like pedal drive. It is a crankset. Mainly to the efforts of the historian Lynn White jr. it was thought in the 1970s that the crank was a difficult to achieve invention - unknown to the classical past and invented in early medieval times (5th century).
The first multiple hand powered crankshafts were depicted by Robertus Valturius in 1463 and later by Leonardo da Vinci. But the first feet powered vehicle by cranks was a French coach c. 1750.
By this seemingly long way to a bicycle crankset it was unbelievable that Leonardo had it already invented in the 1490s. The crankset was such a simple human power source, why were the large treadmills then still used for centuries?
The crank theory of White jr. collapsed in the 1980s after the find of a Roman metal crankset got public. His theory had not accounted the transmission statistics. Further, the first mention or depiction of a technical invention does not indicate it was invented then. Rather simple things could be much older.
The first feet powered crankset vehicle, a paddle-wheel boat c. 1490, was depicted by Leonardo around the same time too. So the pedal drive is no longer an argument for a fake. But it should be known why it was one in the 1970s.
There is general agreement that the sketch was not by Leonardo but a rather unexperienced hand. The surrounding of the sketch are obscene graffiti of penises walking towards an anus named "salaj" and a crude caricature of a youth. It is certain that someone did a destruction job on Salai, Leonardo's closest pupil. Salai (Gian Giacomo Caprotti, 1480-1524) came by the age of 10 to Leonardo and stayed with him until his death. He was favorably mentioned in his last will and according a historian he died in 1524 "under mysterious circumstances."
By the suggested time of the drawing, 1493, Salai was about 13 years old. The other pupils were teens too and not much older. Salai worked as an assistant and model for Leonardo and became a painter. Some 16th century writers suggested their relationship went far beyond teacher pupil. If true it may be a hint how Salai got his information.
Initial Salais behavior was poor and he was not popular by the other pupils. So a causal line suggests that Salai did the sketch and another pupil the graffiti revenge nearby. Marinoni fund part of the graffito continued on the back of another sheet, folio 132. And some of the black crayon of the graffito did a stamp on the adjacent folio. So folio 133 and 132 were originally one sheet and folded together for some time after the graffiti drawings. Because of the graffiti Leonardo only used the front of both sheets for sketches on fortifications.
Probably by Leonardo the sheet was then cut in two. This complex traces of the sheets physical history is crucial but not always considered by the forgery accusers.
Details of the bicycle sketch suggest the kid only saw some drawing but not fully understood the mechanism. Some errors suggest what he saw was in perspective view he was unable to copy from memory.
There is no similar drawing of a bicycle elsewhere in the known heritage of Leonardo. But it was found that relevant parts for a bicycle were depicted in a Codex Madrid on sheets from about the same time 1493.
The Codices Madrid I and II are bound in red Moroccan leather and contain together 349 folio sheets with drawing and text by Leonardo. Madrid I is Leonardo's masterpiece collection of mechanical "gadgets, gears, and inventions".
It was bound to a codex by Leonardo himself. It has survived almost intact, except for 16 pages, which have been torn out and seem to have been lost. The find of this two codices in 1965 was "the most important 20th century find in a library and the most important Renaissance find ever."
It was found by chance when the Bostonian Romanist Jules Piccus searched for lyric manuscripts. He went systematic through the catalog but continued the orders to the next signatures in the hope to get more lyric writings. Instead he got in the reading room the lost codices of Leonardo. He immediately recognized the unique script and ordered to microfilm the codices. He presented his discovery with Ladislao Reti the international press at 7th Feb. 1967 in Boston.
There was a search for the codices in the National Library of Madrid in 1898 and it is hard to understand why it was not found under only 30,000 manuscripts. About the 1965 find two other but less credible stories circulate.
In 1997 Lessing suggested that this news was the motivation to create the bicycle fake. But the drawing of this chains in Madrid I were around the same time Leonardo did the fortification sketches on the bicycle folio too. So Salai and his other pupils this time had access to the chain drawings too.
The cogs of one chain in Madrid I had a cubic shape that wont work. Some of the cogs at the bicycle had that error too. But others at the rear wheel seemed to be of a more pointed shape. The cubic shape error suggests that the kid did a redraw from memory and was fooled by a sketch today in Madrid I.
In his book 1974 Augusto Marinoni presented a reconstruction of the bicycle that later was build in full scale and got well known. It had a chain drive but a fixed none steerable front wheel. The steering handlebars are there only a rest place for the drivers hand. He agreed that without steering it would not work. In a later writing he classified the bike under "Leonardo's Impossible Machines" and wrote:
But from a technical view Marinoni created an impossibility. An unstable two wheeler is no inventive idea but makes no sense at all. It would be laughable crazy around 1500. Why not to use a tricycle instead? Further thought: Any technican would as first idea have placed the pedals on the front wheel hub to avoid the costly chain drive. But even with a steerable bicycle that would not work too. The pedal forces would interfere with the forces of the gyro or trail stabilization. So a chain drive makes only sense if the inventor already tried the front wheel pedals and failed there. But a fixed front wheel is nowhere in such a possible line of development. It is really unbelievable for a person with technical background.
In 1983 a paper by Foley, Blessman and Bryant changed the whole problem of Leonardo's bicycle. It suggested that it was steerable but in a way never ever build in modern times. The front wheel was in a wide fork and could maybe turn up to 15¬į to each side. That was sufficient for any normal operation. Such a design allowed the wheel the small gyro stabilization movements needed to be a stable bicycle. It is today known as "hub-center steering" (HCS) because it got some use again for motorbike racing since the mid 1980s.
During their work they had support by the cycle specialist Derek Roberts. He found that in 1885 the British Quadrant Bicycle Company build bikes with hub-center steering but only for a few years. Therefore after this 1983 paper the term "quadrant steering" came up too.
The paper somewhat focused on a Quadrant like design but suggested different ways to realize it. They thought the inverted "T" below the handlebars was direct involved in the steering. After prior work of Foley and Bryant a full scale proof of concept model (0.5 m wheels) was build by Edward R. Blessman in 1980. The front wheel was suspended by chains. It was the most simple way to realize a hub-center steering but difficult to predict analytical.
It was possible to ride the bike. Blessman: "Riding was odd. It always wanders a bit, won't track real straight. But on a rough surface that might be helpful." It was unstable at higher speed. Probably the chains interfered with the gyro forces. A chainless more complicated version with levers was drawn in the paper of 1983 and later build. It had some far link to the racing HCS of the later 1980s.
To present a Leonardo like working HCS for wikipedia a simple sketch was developed. In several talks it evolved to a more complicated but much more folio 133 like design. In the pre trail version the "T" only had the function of a grip to hold the sliders 90¬į rotated to part the HCS and front wheel from the bike.
In the last version it got a trail stabilization for low speed. But there was no way found to get the "T" useful again. It looks very much like Salai`s sketch, more than any design before. It is far from the Quadrant solution and is a hub-center steering never build yet, neither in a bicycle nor a motorbike.
Comparing this new interpretation with folio 133v suggests the visible axle is in the most forward position. That is to expect by a maximum right turn of the wheel. The sliders of 133v are sketched in shifted position what agrees with that situation too. So the original drawing Salai saw was probably intended to explain the function of the hub-center steering. It seems unclear whether the kid really understood the principle of what he draw but he did a good memory job. The sketch of folio 133v shows now some unique indications for hub-center steering:
The 1983 paper should have stopped any forgery accusations because the sketched design suggested now a plausible way of development. Unfortunately it was written in German and by the technicalities not easy to understand. It got not wide known. In 1987 even Marinoni kept to his fixed front wheel and did not mention this paper.
The most vocal fraud accusations came in August 1997 by Hans-Erhard Lessing. Lessing was retired curator of the Museum of Technology and Labour in Mannheim - the German city where Karl von Drais build the first bicycle in 1817. It seems Lessing saw it as his duty to defend the priority of Drais. In 1997 he presented the Lenardo sketch together with a French and a British priority claim that were both already dismissed by historians.
Lessing cited the 1983 paper but did not mention the hub-center steering. He maintained that the sketch showed a non-steerable two-wheeler. He pointed out that this was similar to a myth created in France in the 1890s about a French priority by de Sivrac of 1791. That myth lasted until 1976. Therefore Lessing argued that any forger before 1976 most have hold the idea that the first bicycle must be non-steerable.
Lessing suggested that on the back of folio 133 only those lines reported by Carlo Pedretti in his "drawing from memory" existed. After the Madrid news in 1967 someone in the lab at Grottaferrata draw in the remaining lines. "It's the sort of thing a bored monk might do," one bicycle expert told New Scientist. According Lessing all happened with the intention to get the priority for the bicycle invention to Italy.
Unfortunately in his paper Lessing called Marinoni a liar. The whole discussion further derailed after journalists - inspired by Lessings paper - suggested the monks and Marinoni were direct involved in the forgery. That Lessing never claimed but it is the impression some readers may got. Marinoni, "one of the great Leonardo da Vinci scholars of his generation", died 4 months later aged 86.
Despite rumors otherwise, there was no physical age test of the drawing yet. The missing crayon traces mentioned by Lessing is no valid point. The whole controversy could only escalate so far because the hub-center steering was ignored. Marinoni, a romanist philologist, could not fully understand the 1983 paper. Others were simply unaware of it. But it seems implausible that a forger would create a design were only very few historians would recognize the principle. A design that worked but in such way was never build before. By that perspective the fraud accusation seems very unfounded.
The hub-center steering allows a plausible line of development but one that has to be done on real size vehicles. No traces of it are found in the records of Leonardo. It could belong to the lost 75¬†% pages of him. But we can be sure that Leonardo never build the bike in the sketch. Had he build it (or the necessary precursors during development) it would have been a news spread rapidly over Europe. A person running on a two-wheeler in 1493 was such an unbelievable sight that it was big news. And Leonardo had to live be the news of his achievements.
The designer of the depicted bicycle did know that it worked. He had solved the stability and steering problem with build precursors. For a first prove of concept he would not have needed the chain drive, Drais had neither. Therefore it was rather simple and the designer would have build it. That Leonardo did not build it indicates he was not the designer.
Who was it? Leonardo lived in the Renaissance. A time when after 1000 years classical texts were collected and read to improve science and living. Leonardo often refers to classical sources in his notebooks.
A straight and simple explanation for the sketch is an origin in a transmitted book from classical time. The kid who did it may actually have seen a drawing in such a source. No such book is known today. But Roger Bacon in the 13th century mentioned a book that presented mechanical and other wonders of the ancients. One was a vehicle that moved itself without horses. Like the spring driven gadget Leonardo had in one of his notebooks. A stable two-wheeler in such a book may be seen by some as a piece of magic and a case for the deadly Secret Courts. The explanation for the stable bicycle needed the gyro theory of the later 19th century.
There are further issues that may point to a late Roman time origin. Foley et al in their 1983 paper suggested the poor roads around 1500 may be a contributing factor to the non spread of the bicycle then. This bike with the size of a modern "safety" was more affected by poor roads than modern ones with tires. Depending on the road condition walking in 1500 could be more energy effective than a bike.
The Romans had the best roads and the most energy effective land transport before the 19th century railways. Their roads were not just hard but a lot had two carved rail ruts, grooves for wagon wheels. These ruts were specially smooth to further enhance the efficiency. The depicted bicycle would be a perfect vehicle then. It was suggested some Roman roads in Britain with only a single rut were related to the bicycle.
This bicycle on a Roman road would be in speed and range similar or superior to horses but much cheaper in daily costs. It had the advantage that its approach would be more silent. A military patrol had a better chance to surprise barbarian intruders. Some other economic advantage may be in mail and individual transport. But the design was neither simple nor cheap and had to rely at least on some small industrial base.
The skills of best 1400 European metal and wood work may be sufficient. But the individual costs for single bikes that type (because of the metal parts) were such high pre 1800 that a horse would be cheaper. The suggested bike only had an economic chance in a serial production. In contrast the Drais design with no gyro but only simple trail stabilization could be well build in single pieces. It was a better suited modern begin.