This rare treasure is called an Optometer and was used to test eyesight. It is made of wood with glass focus lens. These were prevalent at the 1800s General Store for self-eye exams and then selecting or ordering glasses. The Bennion book shows a later model of 1870 with boxwood extension & brass view lenses on page 150, so we would date this from early 1850s to 1870s. Later models from 1870 on were made of brass metal & boxwood and starting in 1875 models were manufactured with all brass. This eye tester is still in working order. The markings are faint but can be read in increments. It measures 11 1/2″ long and is 1 1/4″ tall. When looking through the eyepiece you slide one part till focus is clear telling the lens needed. It is made of wood and has four small age cracks but still in good shape.