Mercury-in-glass thermometer the thermometer, the bulb is made to reach thermal equilibrium with a temperature standard such as an ice/water mixture, and then with another standard such as water/vapour, and the tube is divided into regular intervals between the fixed points. In principle, thermometers made of different material (e.g., coloured alcohol thermometers) might be expected to give different intermediate readings due to different expansion properties; in practice the substances used are chosen to have reasonably linear expansion characteristics as a function of true thermodynamic temperature, and so give similar results. The application of mercury (1714) and Fahrenheit scale (1724) for liquid-in-glass thermometers
Six's thermometer and minimum scales; this shows the current temperature and should be the same on both scales. If the two readings are not the same, then the instrument scales are not correctly positioned or the instrument is damaged. The maximum and minimum readings are recorded by two small steel markers which are sprung into the capillary tube so that they can slide, but only if a force is applied to them, either by being pushed by the mercury or under the influence of an external magnet. Before a new maximum or minimum reading can be taken, the thermometer must be reset