Thermometer, Europe, 1801-1900

Thermometer, glass, Centigrade, European, 19th century

Thermometers contain mercury. This liquid metal expands on contact with heat. The property gives an accurate indication of temperature. German physician Carl Wunderlich (1815-77) began taking the temperatures of patients on a daily basis during the early part of his career. His extensive data monitored the effects of various diseases on body temperature. It also allowed him to calculate the average expected temperature of a healthy individual. His pioneering work was published in 1868 as ‘The Temperature in Diseases.’ The work showed diseases could be identified by the temperature patterns of the patient as well as the stage of the disease. Thermometry was initially controversial, but became an important diagnostic tool.