 The urge for conceptual extension, in the Wedgwood case, was rooted in a widespread feeling that there was a property in the pyrometric range that was continuous in its meaning with temperature in the everyday range. Where did that feeling come from, long before there was any well-defined and agreed-upon theoretical concept of temperature? If we look closely at the situation, numerous subtle and often-unspoken connections do emerge between pyrometric temperature and everyday temperature. In the first place, we do bring objects to pyrometric domains by prolonged heating—that is to say, by a prolonged application of ordinary processes that cause the rise of temperature within the everyday domain. Likewise, the same causes of cooling that operate in the everyday domain will bring objects from pyrometric temperatures down to everyday temperatures; that is precisely what happens in calorimetric pyrometry (or, when we simply leave very hot things out in cold air for a while). These concrete physical operations provide a continuity of operational meaning between two domains that are not connected by a common measurement standard. Here again we need to articulate something that Bridgman already did imply: not all instrumental operations are measurement operations (for instance, we may know how to make iron melt without thereby obtaining any precise idea of the temperature at which that happens). Operational meaning even in the narrow, instrumental sense is broader than meaning specified by methods of measurement.