Self registering, clinical Centigrade thermometer, made by Mariaud, French, 1801-1900 Self registering 1801-1900
Hydrometer, Baume, glass, in metal case, probably French, 19th century Hydrometer, Baume, glass 1801-1900
Glass and mercury hydrometer, with case, made by Thomas O. Blake, 58 Hatton Garden, London, EC, England, 1830-1920. Glass and mercury hydrometer 1830-1920
Hydrometer, glass and metal, Twaddle, in metal case, European, 19th century Hydrometer, glass and metal 1801-1900