Strange question for HN .. anyway, plenty of people bake today without a thermometer. It requires &quot;knowing your oven&quot;, such as by doing a reference batch of cupcakes to see the heat distribution. There&#x27;s also various techniques for assesing whether a cake is done (does a wooden skewer inserted come out clean?)<p>Coal and wood fired ovens usually have a huge thermal mass so once it&#x27;s up to temperature with a particular size fire it will stay there.<p>Edit: the gas oven doesn&#x27;t predate the thermometer, but traditionally is set by &quot;gas mark&quot; rather than a thermostat. Old recipies would say &quot;gas mark 7&quot; etc.