Description

UNUSUAL SECTOR BY BRANDER, German, c. third quarter 18th century, finely signed on the brass sector hinge “G.F. Brander.” This large sector opens to a full 25-3/4″ (65 cm), finely made with arms of boxwood, three leaf sector hinge of brass and steel, and brass terminals on the ends. The arms bear twin sector scales of equal parts, divided every unit from 0 to 200, punch-numbered every 10 units. Condition is excellent except for considerable warping of the arms.

Georg Friedrich Brander (1713 – 1783) was probably the finest and most prolific German scientific instrument maker of his time, constructing a wide variety of innovative astronomical instruments, microscopes, surveying, navigation, and demonstration instruments, etc., and publishing extensively on the subject (see Brachner et al., 1983). No single-purpose sector like the present one is evident in the extraordinary collections described by Brachner, but in a famous painting Brander seems to be holding just such an instrument (Brachner p.23).

The sector’s double “line of lines,” as it is often called, is particularly useful for subdividing, using a pair of dividers, any given line into any number of equal parts, or in fact to solve for proportional parts. A good description is found in Hutton’s A Philosophical and Mathematical Dictionary (1815).