Six's self-registering thermometer, Miller pattern, 1869-1872

In 1780 James Six (1731 1793), a retired business man, designed a self-registering thermometer to measure and record maximum and minimum temperatures. This popular pattern was used for taking sea temperatures for the next 90 years, when Dr W Miller (1817-1870) modified the design for deeper waters, and had it made by the London instrument maker Louis Casella (1812-1897).