This Bimetalic Actinograph was designed by the British Meteorological Office & records the shortwave radiation received from the sun & sky on a horizontal surface.
The movement operates using sensitive elements of a blackened bimetallic strip mounted at one end on two shaded strips. The free end of the blackened strip records deflections proportional to the incident radiation. This recording is made on a standard daily rotation clock drum.
The combination of black & shaded strips provides compensation for ambient temperature changes. The element is exposed to the radiation through a hemispherical glass dome mounted in the top of the white painted metal cover.
This particular instrument has never been used & still has the metal ‘top hat’ cover fitted at the factory for protecting the dome in transit. It is therefore in exceptional condition. The cost new in 1960 was £100, equivalent to over £2100 today. A quantity of charts in arbitrary units from 0 to 80 will be supplied with this unique instrument.