The lenses illustrated here are an actual pair from the inventory that the couple had with them in 1942-1944 while travelling to fit German officers. They were handed down by their daughter Brigitte Mueller-Welt Caffrey (who autographed the modern container into which they had been placed) and from thence to the museum via Mr Al Vaske in 2005. It's great to be able to assign a specific two-year date window to objects such as these. Although there would originally have been tens of thousands of these lenses, their provenance will in most cases have been lost. Many Mueller-Welt lenses were carried home as trophies by Allied soldiers after the war. They are both hand-blown glass scleral lenses and have been marked around the periphery with yellow ink. Adolf Mueller-Welt (1904-1972) began blowing lenses in 1929 having previously relied on a moulding technique. His product was noted for being very stable; you could submerge his lenses in boiling water then transfer them to iced water and still not break them.