A MUSICAL SECTOR, German or Italian, c. late 17th century, made of brass, reverse tapered in thickness, opening from 7-1/2″ to 14-1/8″ (19 to 36 cm). One side is finely divided with twin sector scales of equal parts (each scale divided twice 0(1)100; i.e., from 0 to 100 by ones), of “Lin Recta” 15(1)2, of “Lin ‘square'” 0(1)60(5)90, and of a wonderful musical scale “fi, G, G-is, a, b, h, C, C-is, D, D-is, E, f.” The other has
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