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"Bisecting gage, a gage formed by a bar carrying two heads or cheeks connected by two arms of equal length, forming a toggle-joint, at which a pencil or scribe-awl is placed. The pencil or awl is thus at equal distances from the cheeks at whatever gage they may be set." -Whitney, 1911

Bisecting Gauge

"Bisecting gage, a gage formed by a bar carrying two heads or cheeks connected by two arms of equal…