Adriaan Metius

Adriaan Metius (1571 to 1635), born Adriaan Adriaanszoon in Alkmaar, was a Dutch geometer and astronomer whose name comes from the Dutch word meten, to measure. He studied at Franeker and Leiden, worked briefly under Tycho Brahe on the island of Hven, and taught mathematics at Franeker, where he was professor ordinarius from 1600 to 1635 in mathematics, navigation, surveying, military engineering and astronomy and was allowed to teach in Dutch rather than Latin. With his father and his brother Jacob, who applied for a telescope patent in 1608, he ran an instrument making business that made optical instruments and a special form of Jacob's staff. He published treatises on the astrolabe and on surveying, and the value 355/113 for pi is traditionally called Metius's number. The lunar crater Metius is named after him.