英语翻译What is a Thermometer?A thermometer is an instrument tha

英语翻译
What is a Thermometer?
A thermometer is an instrument that measures the temperature of a system in a quantitative way.The easiest way to do this is to find a substance having a property that changes in a regular way with its temperature.The most direct 'regular' way is a linear one:
t(x) = ax + b,
where t is the temperature of the substance and changes as the property x of the substance changes.The constants a and b depend on the substance used and may be evaluated by specifying two temperature points on the scale,such as 32° for the freezing point of water and 212° for its boiling point.
For example,the element mercury is liquid in the temperature range of -38.9° C to 356.7° C (we'll discuss the Celsius ° C scale later).As a liquid,mercury expands as it gets warmer,its expansion rate is linear and can be accurately calibrated.
The mercury-in-glass thermometer illustrated in the above figure contains a bulb filled with mercury that is allowed to expand into a capillary.Its rate of expansion is calibrated on the glass scale.
The Development of Thermometers and Temperature Scales
The historical highlights in the development of thermometers and their scales given here are based on "Temperature" by T.J.Quinn and "Heat" by James M.Cork.
One of the first attempts to make a standard temperature scale occurred about AD 170,when Galen,in his medical writings,proposed a standard "neutral" temperature made up of equal quantities of boiling water and ice; on either side of this temperature were four degrees of heat and four degrees of cold,respectively.

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