opera glasses

These opera glasses could be divided into three parts from the top to the bottom including two circular eyepieces, three flat bridges and two cylindrical lenses barrels plus one circular focus ring (figure 1&2).

The materials of metal components are deemed to be brass from the former owner, and this could be confirmed by their golden colour (Barclay et al. 2020). Die-casting technique might be used for manufacturing. Only 1.5 cm concave lenses and 3 cm convex lenses are used for magnifying the image. The surface of the two lenses barrels is covered with 21 stripes. They could be mother of pearls that contain aragonite because of iridescence with a parallel pattern (Liu 2001). Figure 3 represents the assemblage.

                      Figure 3. The assemblage of opera glasses (drawn by author).