CHRISTIAAN HUYGENS, Copia copiae exhibitae ab Hadr. Van der Wal 1682 ..., ms.
Universiteitsbibliotheek, Leyden, Ms. HUG 1, ff. 119-120
Facsimile

In 1637 René Descartes attributed the invention of the telescope to Metius. About half a century later the jurist Hadriaan van der Wal showed Huygens a copy of the patent application in which Metius stated that Lipperhey had preceded him.