Two astronomers observe the firmament in a woodcut circa 1545 by
Heinrich Vogtherr the Elder.
Photo: akg-images
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Frontispice and title page of the third London edition of Sir Isaac
Newton's "Philosophia naturalis principia mathematica",
1687.
Photo: akg-images / British Library
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Charles Darwin, circa 1870.
Photo: akg-images
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The northern firmament, from Christoph Cellarius' "Harmonia
Macrocosmica", 1660.
Photo: akg-images
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A manuscript page from Leonardo da Vinci's "Sul volo degli
uccelli" (On the Flight of Birds), with a mechanical reconstruction
of a bird's wing, now in the Biblioteca Reale, Turin.