 The connections listed above rest on very basic qualitative causal assumptions about temperature: fire raises the temperature of any ordinary objects on which it acts directly; if two objects at different temperatures are put in contact with each other, their temperatures tend to approach each other. There are semi-quantitative links as well. It is taken for granted that the consumption of more fuel should result in the generation of more heat, and that is partly based on a primitive notion of energy conservation. It is assumed that the amount of heat communicated to an object is roughly proportional to the amount of change in its temperature (barring changes of state and interfering influences), and that assumption is based on the rough but robust understanding of temperature as the “degree of heat.” So, for example, when a crucible is put on a steady fire, one assumes that the temperature of its contents will rise steadily, up to a certain maximum. That is exactly the kind of reasoning used by the chemist John Frederic Daniell (1790–1845) to criticize some of Wedgwood’s results: