13
Nov
tac2b
![TESSERACT](https://www.fleaglass.com/wp-content/uploads/2019/11/TESSERACT_avatar_1574890198-145x145.jpg)
About the Author: TESSERACT
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].