Brass sector signed "C.W' made by Charles Whitwell between 1600-11, near St. Clement's Church (without Temple Bar), London.

Sectors are mathematical instruments that were used for calculations concerning proportion and for making small measurments. They were particularly useful for technical drawing.. Charles Whitwell (active 1592 - 1611) was an engraver and mathematical instrument maker who engraved sectors for the mathematician Thomas Hood. He was apprenticed to Augustine Ryther in 1582 and became a Freeman of the Grocers' Company in 1590. His workshop was located near St Clement's Church, near what is now Aldwych, in London.