| A brass sector (length
closed 5.1 in., open 9.4 in.) features two logarithmically scaled
arms joined at a pivotal hinge. A line of English inches (2.54 cm)
occurs on the inside edge of one arm, while the back edge when opened
is divided evenly into eight French inches (2.75 cm); the first
block of both scales is further divided into 12 increments. A small
set pin ensures that the arms line up when the instrument is closed.
When used with a set of dividers, the sector enabled problems involving
proportions to be solved instrumentally. |
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