I make my cheese in a double boiler (one smaller kettle inside a larger one) and when I measure the temperature of the milk or the curds the temperature varies depending on the depth to which I insert the probe. I presume that that is quite normal given the height of the column of milk and the source of the heat towards the bottom (and sides) of the inside container. When the temperature of the recipe calls for 90 F or 100 F from where does one measure the temperature- from just below the surface, from just above the bottom, from the side or the center? And if the range of the temperature is 5 F or more how concerned should I be? (My working assumption has been that the recommended temperatures are more like ball park figures than anything hard and fast but that is just an assumption: that said, the cheese I make turns out without any obvious problems. Thanks