THE PATENTED BIASCOPE, American (Rochester, N.Y.), c. early 20th century, by Wollensak. Measuring 3-3/4″ wide, these pocket binoculars have 6x magnification, with communal focusing by central lever. Fine with light wear.
Ask the Dealer
David and Yola Coffeen both have enjoyed academic careers, as planetary astronomer and as linguist/educator. But since 1982 (yes, 1982!) they have been full-time dealers in early scientific and medical instruments, under the name Tesseract. Selling primarily by catalogue (over 100 issued so far) they also have a web presence at www.etesseract.com, and can be contacted at [email protected].