A thermograph by F. Darton of St John St London C. 1900.
This lovely item, besides being a precise scientific instrument, is a work of art itself. The case is made from copper with brass fittings, and sits on a cast iron base. This mechanical device is designed to record temperature over a seven-day period.
It consists of a wind-up mechanical rotating drum holding a temperature chart, plus a bi-metal mechanism sensitive to temperature change. A stainless steel arm with an ink nib records the fluctuating temperature readings on the rotating chart.
Thanks to Science Museum Group for this entry:-
“Thermograph with glazed copper cover and spring dampened base by F. Darton & Co., London, England, 1900-1910. Later used to make ambient temperature measurements next to the British Experimental Pile 0 (BEPO) reactor at the Atomic Energy Research Establishment, Harwell Oxfordshire in the 1950s”