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Physiology of the Impossible - continued...

The self-made bird

The enigmatic behavior 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 (Über das Schweben der Raubvögel). 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 cave floor, 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.

Exner's artificial buzzard in action

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".

Reference: Geimer, Peter. 2001. Physiology of the Impossible. Exner meets mythology.. The Virtual Laboratory (ISSN 1866-4784),