Tychonis Brahe Dani Epistolarvm astronomicarvm libri
cvm Caesaris et Regvm qvorvndam privilegiis, Vranibvrgi, 1596
4. The Keen Observer
This is the early correspondence of Brahe with the learned Landgraf William of Hesse containing detailed instructions for the construction of astronomical instruments. Brahe's observatory at Uraniborg, on the island of Hveen in Denmark, is shown; here the last of the pre-telescope observations were made, which enabled Kepler to discover the laws of planetary motion. Printed on Brahe's private press in a few copies, this is Brahe's own copy with his portrait in colors and arms supra-libros on the covers.