A
Temperature is measured by means of a thermometer (温度计). One general form of thermometer depends upon the fact that most solids and liquids expand as their temperature rises. There are one or two exceptions. There is, for instance, a kind of steel called invar (from “invariable”) which does not change its dimensions as temperature changes; it is valuable for making pendulums (钟摆), since, if the length of a pendulum changes, its time of vibration changes. It is also used for making very accurate measuring scales. In both cases, then, changes of atmospheric temperature have no effect if invar is used.
