理想气体为热力学理论提供了一个简单的实例，为测量热力学温度提供了一种简单的温度计。

Ideal gas offers a simple example of application and a simple thermometer for thermodynamic scale of temperature.

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So he grabbed his thermometer, and went and made a couple of measurements and discovered the first law of thermodynamics.

所以他拿来了温度计，进行测量,后来就发现了热力学第一定律。

麻省理工公开课 - 热力学与动力学课程节选