If the two glass thermometers got down to exactly 32F, then they are calibrated. Those two should be the thermometers you use to set the temperature in your incubator. When the incubator shows the temperature you need to incubate eggs, write down what the digital thermometer is showing. It won't matter what the temp is showing on the digital thermometer, as long as you use the same temperature every time. For example, if you want to run your incubator at 100F... you adjust the controller until both of your glass thermometers show 100F. When they both show 100F, see what the digital is reading. 37.8C is 100.4F, but the digital thermometer may be showing 40.8C. It may be a little higher, or it may be a little lower, but it doesn't matter. Whatever it is reading when the glass ones hit 100F, write it down and keep it on the incubator so you will always know what it's supposed to be reading. In other words, you will use your glass thermometers to set the temp, and the digital one will just be used as a backup.
