Medical thermometer and displaying temperature became available, electronic thermometers (often called "digital", because they display numeric values) have been used. Many display readings to great precision (0.1 °C or 0.2 °F, sometimes half that), but this should not be taken as a guarantee of accuracy: specified accuracy must be checked in documentation and maintained by periodical recalibration. A typical inexpensive electronic ear thermometer for home use has a displayed resolution of 0.1 °C, but a stated accuracy within ±0.2 °C (±0.35 °F) when new. The first electronic clinical thermometer, invented in 1954, used a flexible probe that contained a Carboloy thermistor. Types
Six's thermometer the mercury, and returning it to the horizontal. The Six's thermometer is known for separations in the mercury column, in particular after shipment, though accidental knocks have been known causes as well. Separations can usually be corrected by swinging the thermometer as is done to reset a mercury clinical thermometer; the centrifugal force forces the mercury together again. Should a marker become partly buried in the mercury, it can either be pulled up again with the magnet or exposed to an extreme temperature that leaves the marker uncovered. If a strong external magnet is used to pull up the markers