Thermometer question

[PotterWatch]

I posted this within another thread, but I thought perhaps I should start a new one for this question. I have two thermometers in my incubator. One is digital and has the hygrometer with it, the other is just a regular one. The regular one reads about 2 degrees higher than the digital. Which one should I believe?

 

[speckledhen]

Can't really answer that. Is the regular one mercury or alcohol type? You almost need a third one to judge by rather than just two. I'm so tired of inaccurate instruments that if I really get into more hatching next year, I plan to buy one with a true accuracy rating made for incubating, rather than a household one.