ABSTRACT
Like all sciences, the subject of thermodynamics too grew out of systematizing empirical data. Needless to say, data has no meaning unless viewed within a reasonably well-defined conceptual framework. The beginning of such a framework is of course in day-to-day sense perceptions and experiences. Clearly the temperatures so measured will depend on the material used in the thermometer, on how its properties depend on temperature as well as on the temperature scale chosen. An apparent circularity at this stage can be removed by using several types of thermometers, i.e depending not only on different materials but also on different properties used for thermometry. One of the most important questions in thermodynamics concerns the nature of heat. It is interesting that none of the gas laws required any understanding of heat for their formulation. In fact their statement only involves the mechanical notion of pressure, the geometrical notion of volume in addition to that of temperature and molar content.
