Antique historic measuring and calculating instrument. The Sector was invented by Thomas Hood in England and Galileo in Italy.It preceded the slide rule as an instrument to perform calculations - multiplication, division and trigonometric. They were used from around 1597. The history and use of the sector is explained in an article The Sector: its history, scales, and uses by ERWIN TOMASH and MICHAEL R.
Briefly, the sector was used with dividers and had different lines for different purposes. The line L was for multiply and divide, this sector has S C and T probably sine cosine and tangent. This sector is marked ROTHWELL MANCHESTER.
Rothwell is recorded as working between 1780 and 1820 making scientific instruments notably telescopes and compasses. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "jennyfowler46" and is located in this country: GB. This item can be shipped to all countries in Europe.