An 18th-Century brass sector and square,

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An 18th-Century brass sector and square,
signed GEORGIUS ADAMS Apud Insigne Capite Tychonis Braheii in Vico Vulgo Dicto Fleet Street. LONDINI, with finely engraved scales for SINUS RECT, PLANA, TANGENTES, PARTIN EQUALIM, SOLIDA, SECANTES, CHORDAS, with additional scales for Jn Mer, CHO, SIN, TAN, LAT, HORA and POL, the folding arm of the square arranged so as to pivot and form a support for both arms of the sector, engraved across both arms a table of metallic symbols -- 19¼in. (49cm.) long fully opened

See Colour Plate 10

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