Biese - Telescope for variable magnification, German Patent 76921 of 1894
A German patent specification granted to Alfred Conrad Biese in 1894 for a telescope of variable magnification, issued as Patent 76921 for examiners and instrument makers. The plate is a numbered line diagram in fine ink on tinted stock: a sectioned barrel with lens elements hatched, dashed sightlines, letter keys, and an external threaded rod with knurled adjusting drum.
