A rare Victorian carved oak and opaque glass

A rare Victorian carved oak and opaque glass maximum/minimum thermometer Unsigned, third quarter of the 19th century The arched opaque glass Fahrenheit scale plate applied with shaped tube arranged to provide a minimum reading to the inverted scale on the left hand side and maximum reading to the ascending scale to the right, the lower bend of the tube filled with mercury acting against markers inserted within the spirit filled sections, the scale further annotated COLD to the upper left margin opposing HEAT to the right, mounted on scroll-carved an oak wall panel for wall mounting, 38cm (15ins) high. This type of maximum/minimum thermometer was invented by James Six (1731-1793) in around 1780 and relies on markers inserted in the tube to remain at the highest position gained by the mercury over a given period, hence a record of the minimum temperature on the inverted scale to the left and highest temperature to the ascending scale on the right can be obtained.