The Wall Quadrant in Uraniborg

Uraniborg was the research centre of the Danish astronomer Tycho Brahe (1546–1601) on the island of Ven in the Öresund. The castle-like building was divided into three parts: The upper floor contained astronomical equipment and was used for observing the sky; beneath this was a floor with tables for calculation and maps, the mathematical laboratory; and the cellar contained the alchemist's laboratory. One of the reasons for this division and arrangement was Brahe's assumption that the microcosm and the macrocosm correspond to one another: "By looking up, I see downwards; by looking down, I see upwards."

The wall quadrant in Uraniborg, 1909, unknown artist; source: Meyers Großes Konversationslexikon, 6th edition, Leipzig 1909, vol. 2, p. 111.