White enamel glass mirror by William Herschel, 1780-1800
White enamel glass mirror by William Herschel, 1780-1800
Six and a half inch concave mirror of enamel (white glass or Tassies compound) prescribed at back:- "no.8, 7 feet enamel mirror (F)" in cardboard round box ("Pl ) with lid, exact focal length 7ft, 3.25 in