Mobile Principle
Mobile Principle
Principle from a 12th cty
Arabian manuscript
In ancient Greece we see no evidence of interest in perpetual motion. Greek knowledge of mechanisms was well developed, as evidenced by the Antykythera mechanism and by Heron's automata. Natural sources of power like water wheels and the labor of slaves, were sufficient for the needs of Greek society. Mechanical ingenuity was channeled toward construction of mechanical toys and temple automata. These often had the appearance of being self-moving, but were powered by hidden power sources such as falling water or sand. Roman authors did not mention any attempt to construct a perpetual machine. However, only a few texts about technology from 2000 years ago have survived.
The idea of perpetual motion originated in the Orient. The first description of a perpetual motion machine was found to be made by the Indian mathematician and astronomer Brahmagupta in 624. In his Brahmasphutasiddhanta, he describes a perpetual motion device: "Make a wheel of light timber, with uniformly hollow spokes at equal intervals. Fill each spoke up to half with mercury and seal its opening situated in the rim. Set up the wheel so that its axle rests horizontally on two [upright] supports. Then the mercury runs upwards [in some] hollow spaces and downwards [in some others, as a result of which] the wheel rotates automatically forever." (transl. S. R. Sarma).1)
The Sisyadhivrddhida Tantra by the Indian astronomer Lalla, written in 748, is the next treatise, where a comparable perpetual motion machine is described. Lalla also refers to a wheel with hollow spokes partly filled with mercury.2)
Around 1150, the Indian mathematician and astronomer Bhaskara described in his Siddhanta Siromani a wheel with containers of mercury around its circumference. He says, "This machine rotates with great power because the mercury at one side of the axle is closer that at the other." (Klemm, S.7)3). Apparently he thought this would cause continual unbalance to sustain rotation. Supposedly he didn’t build and test the device, and many other authors did not make this final step as well.
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| Brahmagupta's Perpetuum Mobile Principle |
Bhaskara's Perpetuum Mobile Principle |
Perpetuum Mobile Principle from a 12th cty Arabian manuscript |
Since the 12th century, the principle of this machine was frequently incorporated into other perpetual motion proposals, and became part of the history of technology. Even today inventors propose variants of this "overbalanced wheel", often in complicated designs containing wheels with eccentric levers and masses attached to them.
We have reached the idea of the imitation of the PM naturae. A wheel as a rotating device has similarity to cyclic events in nature, like years. Thus the wheel mechanism represents an esoteric and religious aspect that can be characterized by buzzwords like return, year's cycle, re-incarnation. Indian temples frequently display wheel symbols. It seems as if the aspect of creating a machine that generates useful work was not the predominant aspect of the indian mathematicians, but to simulate an eternal cycle. The machine is to be regarded as a model for philosophical aspects, not for engineering tasks.
A wheel symbol on the Indian Sanchi stupa. From
Strzygowski Asiens bildende Kunst, 1930, fig. 272, p.285
Perpetual motion machines based on wheels with attached eccentric masses, shifting masses or containers filled with liquid are called indian, persian or arabian perpetual motion machines.
The middle ages' architect and master-builder Villard de Honnecourt (around 1235) seemed puzzled by the unsuccessful attempts of other perpetual motion machine inventors. To close the discussion and end the ignorance of others, he drew a machine both simple as ingenious, whose operating principle is based on an odd number of moveable heavy hammers mounted to the rim of a wheel:
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| Villard de Honnecourt's famous unbalanced wheel. The original comment reads "Maint ior se sunt maistre dispute de faire torner une ruee par li seul. Ves ent si con en puet faire par mailes non pers ou par vif argent" |
Villard’s reasoning isn’t entirely clear, but apparently he assumed that at the wheel would always have four hammers on one side of the axle, and three on the other side, keeping it in continual unbalance. Villard did not realize that the whole system would reach static equilibrium with three masses at either side and one in the middle hanging straight down. Even some of today's perpetual motion inventors fall into the same trap. This is what I call persistence of limited vision: eight hundred years have passed, and these lessons have not been learned!
During the Renaissance interest in perpetual motion machines was widespread. For example, some drawings of perpetual motion machines by the architect and master-builder Francisco di Georgio have survived. A very fine example is this water-driven mill with an additional pump engine. (Ms. Ashburnham 361 fol. 36r, cf. Galluzi p. 136)
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Let's examine the details of this mechanism: This machine uses closed
water circulation. Such machines are called recirculation mills or
dry water mills. Since the water does not come from external sources,
it was called aqua morta i.e. "dead water". In this example, falling
water turns a water-wheel which drives the corn mill through a gear mechanism.
To raise the water up again, a crankshaft and two levers drive a two-cylinder
piston pump which lifts the water to the feeding canal of the water wheel.
Di Georgio gave more than one example of these machines but we have to be careful. Some of the machines are impractical, but they may work. And of course, machine drawings like these also were made to impress the reader and to demonstrate the combination of many construction elements in a single device. |
In 1618 the English physicist and mystic Robert Fludd (1574 - 8 Sep. 1637) described a recirculation mill, which raised the water with a chain pump powered by a water wheel, driven by the same water! However, Fludd added his disclaimer, stating that this was the invention of a "certain italian" which was "being the unworkable repetition of an aged idea". For details, cf. the physics section.
In the middle of the eighteenth century the first systematic research on water powered machines was made in order to improve these devices. 250 years after Leonardo, machines driven by aqua morta were relegated to the scrapyard of technology. It wasn’t until the mid 1950s, until these were resurrected by Viktor Schauberger. Under the name of "trout turbines" or "vortex turbines" they are still discussed today by Schauberger's followers. I've never heard of a working example…
Apparently, di Georgio's machines were known to Leonardo da Vinci4) who had a life-long interest in machines of all kinds, including perpetual motion machines. Some of his drawings of recirculation mills with archimedian screws have survived. He described a complex mechanism using a wheel with mercury-filled containers. The Deutsches Museum in Munich has a reconstructed model on display. Leonardo was an excellent observer and knew the theory of machines quite well. Although the principle of conservation of energy was unknown at his time, Leonardo had a clear concept which came very close to it: "Falling water lifts the same amount of water, if we take the force of the impact into account [...], but from the power of the machine we have to subtract the friction losses in the bearings." (Michal p.17). Sketches by Leonardo's hand of pure mechanical perpetua mobilia, which use rolling balls, are also known.
Leonardo's rolling ball machines (cf.
Wallace, Leonardo da Vinci,
p.168)
Although Leonardo had a continuing interest in perpetual motion machines, he held a very skeptical opinion about the possibility of their practical implementation. In one of Leonardo's sketchbooks we find a drawing illustrating Leonardo’s proof of the impossibility of an overbalanced wheel PM.
Leonardo's proof of the impossibility
of a mechanical PM with levers
(cf. Cianchi p.83 / Cod. Madrid I,
fol.145r.)
This drawing shows excellent insight into forces, torques and levers. The analysis of forces can be regarded as almost modern. Leonardo closed his considerations with the words: "O you researchers of perpetual motion, how many harebrained ideas have you created in this search. You may as well join the alchemists." (Michal, p.17)
Even today, Agostino Ramelli (1531[?]-1608[?]) is regarded as an important engineer. His great opus Le diverse et artificiose machine is a rich treasure for historians of technology. There we find many modern mechanisms which are attributed to later times. E.g. Ramelli invented ventilators and a pump, which today is named after its "inventor" Gaede's capsule pump. The end of the renaissance and the baroque period were the heyday of perpetual motion proposals. But Ramelli was too much a practical engineer to fall victim to the idea. We find no mention of it in his works. Or to be more precise, almost no mention of it. In chapter 43 he describes a wheel for raising water, which contains a mechanism to improve the power of the device. This mechanism is the classic overbalanced wheel. After a short description of the machine, Ramelli adds this disclaimer: "You should know that the interior of this wheel was designed to please a gentleman who requested me to do it because he thought that since the current of the river was too slow it should be aided by a wheel. Thus anyone can make use of it if he judges it suitable."
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1. Transl. S. R. Sarma, Astronomical
Instruments in Brahmagupta's Brahmasphutasiddhanta, Indian Historical
Review, XII 1986-87, p. 69-71) and Perpetual Motion in Machines and their
Design in Ancient India, Physis - Rivista Internationale di Storia della
Scienca, vol. XXIX (1992) fasc. 3 p.665-676.
2. Thanks to Prof. D. Simanek who passed a note by
Prof. G. Tee to my mail mailbox! Cf. G. Tee in Historia Mathematica,
11 (1984)p.327-329. This was an important hint forther further library research
work..
3. Original German text: "Die Maschine dreht sich
mit großer Kraft, weil das Quecksilber auf der einen Seite näher
an der Achse ist als auf der anderen Seite."
4. Science knows that Leonardo owned a copy of a
treatise written by di Georgio. Moreover, there is strong evidence that Leonardo
has met di Georgio.
| Last update: 22 May 2004 / |
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