Pair of maximum and minimum thermometers by W. Watson & Son (Richardson's patent, 189). Centigrade and Fahrenheit scales on ivory. Kew observatory No. 22941 (Kew certificate)
Pair of maximum and minimum thermometers by W. Watson & Son (Richardson's patent, 189). Centigrade and Fahrenheit scales on ivory. Kew observatory No. 22941 (Kew certificate)