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.
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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@example.com.