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
Breguet's thermometer connected to an index, which projects over a graduated circle (b). The expansion of silver with temperature is almost twice as great as platinum, with gold being in somewhere in between. The result is that a temperature rise or fall will cause a corresponding twist in the spiral, moving the index. The slip of gold in between is to prevent "sudden starts". Breguet's thermometer Breguet's thermometer, also called a spiral thermometer, is a type of thermometer which uses the expansion of metal under heat to produce a measurement more sensitive, and with a higher range, than both mercury and air