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Peter Geimer Physiology of the Impossible Sigmund Exner, professor of physiology at the University of Vienna, used to spend his holidays in the Austrian mountains. On his long mountain hikes Exner often had a puzzling experience: From his elevated standpoint in the mountains he observed a buzzard in the valleys beneath him flying higher and higher and ending up moving in circles. In circling the buzzard constantly gained height - although its wings did not show any mouvement. How can a bird keep its body in the air and even gain height without flapping its wings? "Here we have a problem", Exner notes, "and in view of such a buzzard - in addition to the common sensation of smallness and humbleness that man has in high mountain regions anyway - I felt the humilation of a naturalist who faces a phenomenon but cannot explain it". The self-made bird The enigmatic behaviour of the buzzards gave birth to a series of experiments that Exner published under the title On the floating of birds of prey in 1906 (?ber das Schweben der Raubv?gel). Exner's investigation started with a memory. On a trip to a meeting of naturalists in Breslau in September 1904 a scene came to his mind that he once had witnessed in a zoo. Exner's imagination presented to him some birds of prey lying on the ground of their cave the outer feathers of their wings intensely trembling. Could this trembling be a kind of floating exercise? As the scientific object was inaccessible - too far away to be examined, unable to fly if caught - Exner constructed an artificial bird made of wire, wood, a buzzard's wing, and a motor. A rotating disc raised the wing, a strong spiral feather drew it back . In order to visualize the corresponding flow of air Exner used white paper strips (fig. 1). In a second step he introduced two electrodes into a living buzzard's muscular system and by use of a Du Bois-Reymond induction apparatus he showed that a trembling of the wings could be provoked by electric impulses. Finally the stylus of a myograph inscribed the wing's vibrations. Exner's studies of these minute curves on the paper manifested a shift that according to Bruno Latour characterizes any scientific research about nature: "Scientists start seeing something once they stop looking at nature and look (...) obsessively at prints and flat inscriptions".
Twenty years before the floating buzzard occupied Exners mind, some other flying objects had accompanied him on his mountain hikes: "Last summer", Exner notes in 1882, "certain figures from great masters' works of art followed me on my lonesome hikes through hills and ravines pushing themselves in the foreground and asking for an answer to their riddle". The riddle Exner refered to concerned those well-known saints, puttos, and angels that painters had depicted for centuries. How could they keep their bodies in the air against the law of gravity? In 1882 Exner published his results under the title: The Physiology of Flying and Floating in the Fine Arts (Die Physiolgie des Fliegens und Schwebens in den bildenden K?nsten). Exner's text is confusing because of its ambivalent heuristics: The author cannot ignore the completely fictious nature of floating bodies in art; nevertheless he treats them as if they should obey the authority of physics and physiology. It seems that even mythology cannot escape the laws of nature. Exner continues to use the language of proof and causality even when it comes to fiction, even when he faces the impossible. Monsters
Exners imagined what a "realistic artist" who aims to depict
"a meticulously exact imitation of nature" would have to
paint in order to present a physiologically correct flying body. In
the case of a sparrow the ratio of the weight of its muscles was to
the total weight of its body as 1 was to 6. Thus, Exner calculated
what a real flying man - given a weight of 60 kg - would look like.
He would have wings and its supplementary muscles would weight 10
kg: "The result would be an enormous hump, whose dimensions would
exceed everything we have seen so far, moreover, it would be located
in the front. Our artist certainly would have constructed something
which is able to fly but something which would not resemble a human
being any more. It would be a monstrum, something from the workshop
of a hell-Breughel". A putto (fig. 2) taken from Raphaels Galathea
(fig. 3) served to demonstrate the physiological and physical impossibilty
of the phenomenon in question. Exner transformed the putto into a
scheme (fig. 4). By taking into account the probable speed of the
flying body, its hypothetical weight, the effect of gravitation, and
the specific weight of air, Exner made some calculations. "The
result is: the putto would advance at a speed of 54 m per second".
Exner modified his formula by putting in a much more probable speed
of 2 m per second. In that case the putto's weight would amount to
a mere 2 g. "It would be easy to blow it in the air." Thus,
Exner concluded: "The pictorial representation of a human figure
that would really have the capacity to fly is impossible." But
what about floating? A floating figure would need to be weightless.
That is: A group of saints floating upwards - as in Albrecht D?rer's
Anbetung der Dreieinigkeit (fig. 5) - would be an absurdity. At least,
they would have no reason to keep their legs down, their heads up.
The saint's hair would stand in all directions. The two angels that
hold the crown in Michelangelos Piet? in Rome would use their muscles
in vain: They would fall down to earth together with the crown they
seem to carry through the air. A realistic naturalist It would be too easy to accuse Exner of beeing naive,
too easy to diagnose a fundamental misunderstanding of artistic imagination.
It is far more rewarding to compare his speculations about the flying
saints with his own research on flying. The interesting point is not
what Exner tells us about painting but what his approach to art reveals
about his own heuristics. One might wonder whether Exner's phantom
of a "realistic artist" who aims to give "a meticulously
exact imitation of nature" betrays the practice of the realistic
naturalist. According to Exner the realistic idea of flight in painting
would only be possible with beings that in reality were unable to
fly. A realistic artist would have to construct "something",
a mere thing, a "monster". Such a monster is Exner's bird-machine:
a hybrid made of feathers and a motor, "something" that
cannot float but allows to study the conditions of floating. Thus,
Exner's research on the floating buzzard is based on models that cannot
float themselves: a self-made bird, an anaesthetized buzzard put into
live by electricity. If they were able to fly they would escape from
the physiologist's laboratory. fig. 1: Exner's artificial buzzard in action.
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