Tanneguy - Opera Glasses with Quick Focus, German Patent 48806 of 1889
A German patent specification, No. 48806 of 1889, filed by E. Tanneguy de Wogan and issued by the Kaiserliches Patentamt, describing a quick-focus mechanism for opera glasses. Line engravings show the binoculars in elevation, plan and cut-away section with hatched interiors, lettered part keys and figure captions, plus a title page with diagonal issue date and embossed patent office seal.
