@47ce6ec1 Mid 20th century (and older) baking books often have a paragraph telling you to scatter flour on the oven floor, then timing how long it takes to brown, to assess temperature. That was back when oven dials didn't have temperatures marked on them, but vague things like "hot" and "moderate" and "moderately hot" (but not "hotly moderate"). Or, if you burnt gas, numerical "gas marks". 

 @32afc0f2 👍