17th-century copper engraving print by Willem Janszoon Blaeu of Tycho Brahe's "great equatorial armillary".The large instrument, constructed around 1585 at Brahe's observatory on the island of Hven, was used to measure the paths of planets and the moon across the sky with high accuracy. Engraving measures 16 1/2" x 11 1/4" In matte: 21 3/4" x 16" In great condition, the paper that is covered by the frame does not look as spotless as the framed piece. Please zoom in on each photo taken. z10749-156