Original Callendar electrical temperature recorder (including integrator) in wooden case, 1897. Callendar Temperature Recorder, 1897 1897
Clearspan P100L single pen temperature recorder with spare chart and accessories, 1970-78. Calibrated to use copper constantin thermocouple. Single-Pen Electrical Temperature Recorder, 1970-78 1970-1978
Single thread electrical temperature recorder in glazed case, by The Cambridge Scientific Instrument Company Ltd., Cambridge, England, 1910-14. Range say 0-1000°C, with 100 charts Single Thread Temperature Recorder, 1910-14 1910-1914