Hiscox, Gardner Dexter, 1822?-1908 · New York, The Norman W. Henley publishing co. · leaf 378
1531. SPHEROMETER.—For meas-uring the curves of spherical surfaces orof templates of lenses by means of agraduated follower at the centre betweeni J two bearings. The scale and nonius arecomputed for the versed sine of a fixedchord length. 1531a. ELLIPSO-GRAPHIC T U R N -TABLE. — The tablesits upon… … 1531&. ELLIPSOGRAPH.—A pairof dividers with points perforated likethe eye of a needle allows of adjust-ing the length of the thread to any sizecurve and holding the end under thethumb on the head of the dividers. Thepoints with their eyes are shown at theright-hand side. 368 DRAUGHTING DEVICES.
Mechanical movements
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