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Sector (instrument)
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The sector, also known as a sector rule, proportional compass, or military compass, is a major calculating instrument that was in use from the end of the sixteenth century until the nineteenth century
A typical English sector, probably from the early 19th century, made of ivory with a brass hinge. This side has scales for lines of lines (L), secants
A typical English sector, probably from the early 19th century, made of ivory with a brass hinge. This side has scales for lines of lines (L), secants (S), chords (C), and polygons (POL), along with a scale of 10ths of inches on the outer edges forming a straight 12-inch rule when the sector is fully opened, and a scale of 100ths of a foot marked along the side (only barely visible in this picture).
The other side of the same sector, with scales for a line of sines (S) and two lines of tangents (T), along with logarithmic Gunter's scales for numbe
The other side of the same sector, with scales for a line of sines (S) and two lines of tangents (T), along with logarithmic Gunter's scales for numbers (N), sines (S), and tangents (T) on the outer edges.
De fabrica et usu menti ad omnia horarum genera describenda (1592), where Giovanni Paolo Gallucci is among the first to describe the sector
De fabrica et usu menti ad omnia horarum genera describenda (1592), where Giovanni Paolo Gallucci is among the first to describe the sector
Clément Cyriaque de Mangin, Usage du compas de proportion, 1637
Clément Cyriaque de Mangin, Usage du compas de proportion, 1637
Marc'Antonio Mazzoleni
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Marc'Antonio Mazzoleni was a Paduan instrument maker best known for his association with Galileo Galilei, for whom Mazzoleni produced instruments including Galileo's military compasses and other instr
Sector (instrument)
…we know today as Galileo's sector is the version with this added capability that he began to produce in 1599 with the help of the instrument maker Marc'Antonio Mazzoleni. Galileo provided Mazzoleni and his family with room and board, and paid him two-thirds of the 35 lire selling price; Galileo would charge 120 lire for…
Galileo's geometrical and military compass, thought to have been made c. 1604 by Mazzoleni
Galileo's geometrical and military compass, thought to have been made c. 1604 by Mazzoleni