An unusual Ivory Nomogram by Negretti and Zambra. One side for English Stones and Pounds/French Kilogrammes/American Pounds. Side 2 Fahrenheit/Celsius/Reamur. In good condition noting small amount of discolouration.
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Fletcher Wallis sells objects and books relating to the history of science, medicine and technology from his unit at Admiral Vernon Arcade Portobello Road. He publishes books through Vernier Press, including Antique Medicine Chests, and Corkscrew Patents from 1795. He has been dealing for thirty five years.