RecordThermometer< 1 of 1 > Back
ThermometerThis type of deep sea thermometer was designed by Henry Johnson in 1861. This example was made around 1870, and was used to record temperatures in the ocean depths. Although unsigned, it was retailed by Negretti & Zambra of London between 1864 and 1885, but did not prove popular. Johnson's thermometer had as its element a bimetallic strip of riveted brass and steel. As these strips flexed under changing temperature zones in the water, they moved an index across the graduated dial (seen in the 'window'), and also pushed pins to record the extremes of temperature reached. Johnson's thermometer proved to have only limited usefulness and was erratic in its measurements, as there was no correction for pressure. During the 1868-70 cruise of the 'Lightening', Charles Wyville Thomson (1830-1882) found the deep-sea thermometers unsatisfactory. Record detailsTo search on related items, click any linked text below.
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