Adriaan Metius

Adriaan Metius (1571 to 1635), born Adriaan Adriaanszoon in Alkmaar, was a Dutch geometer and astronomer whose surname comes from the Dutch word meten, to measure. He studied at Franeker and Leiden, where Rudolph Snellius taught him, spent a short time with Tycho Brahe on the island of Hven, and lectured at Rostock and Jena before returning to the Netherlands. From 1600 until his death he held the chair of mathematics at the University of Franeker, a post that also covered navigation, surveying, military engineering and astronomy, and he was allowed to teach in Dutch rather than Latin. He wrote treatises on the astrolabe and on surveying, and with his father and brother he ran an instrument-making business. He is remembered for publishing his father's estimate of pi as 355/113, which is still called Metius's number, and a lunar crater bears his name.