I have just bought a large (22" x 15") Sankey 22 watt heated propagator for
£20. I put some cuttings in it and switched it on. With an ambient
temperature of 62F, a thermometer pushed to the bottom of the pot registers
a temperature of 98F, in the middle of the pot it is 85F and resting on top
it is 72F. I have compared the thermometer with another and am happy that
it is accurate. The propagator is placed on a sheet of polystyrene.

This sounds as though it could fry cuttings pushed in too deep. What
temperatures should I be using and at what measurement point. It has only
been on for 36 hours so far and nothing has died yet. Presumably this steep
gradient is normal, irrespective of the actual temperatures.