Thank you for visiting our Tesseract web site. We have been full time dealers in early scientific and medical instruments since 1982. In addition to the web site, we publish several catalogues per year, each with dozens of instruments fully illustrated, described and priced, and are now up to Catalogue 111. Please contact us if you would like a single copy ($10), or if you wish to subscribe ($35 for four issues -- approximately one year).

We are always interested in buying single items or collections.

In addition to buying and selling early instruments, we can perform formal appraisals of your single instruments or whole collections, whether to determine fair market value for donation, for insurance, for loss, etc. We were recently engaged to appraise a medical collection of several hundred items being donated to an American museum, and to appraise a major European collection of early scientific instruments, being insured for a loan exhibition.

David Coffeen, Ph.D
Yola Coffeen, Ph.D


Scientific Instrument Society
Historical Medical Equipment Society
American Association for the History of Medicine
Antiquarian Horological Society
International Society of Antique Scale Collectors
Surveyors Historical Society
Early American Industries Association
The Oughtred Society
American Astronomical Society

International Coronelli Society
American Association of Museums

RITTENHOUSE. The Journal of the American Scientific Instrument Enterprise, has had twenty-three years of print publication, first as a quarterly, then in a double-thickness biannual format. This journal, which we co-published, wss dedicated to articles about the history of instruments made, sold, and/or used in the Americas. Most of the 70 print issues, featuring many dozens of articles on all types of scientific instruments, are still available, either singly or by volume. Please contact us for these back issues.

Box 151
New York 10706 USA

telephone: 1-914-478-2594



Over the past 38 years we (David & Yola) have accumulated a few (i.e., several thousand) reference books on the subject, and here you see us in situ with a couple of instruments.
We also exhibit at the occasional fair: