Alright so I have a the mercury thermometer that came with my Hova Bator, and a brand new Accurite thermometer/ hydrogometer. I have had two digital thermometers in the last year and both have read about the same, and two mercury ones that have read about the same. I freaked out when the mercury read 5 degrees higher than the digital, however when I incubated eggs with the mercury I had severely delayed, issued hatches. I had slightly early, but better hatch rates when I hatched with the digital. Which would you trust? I cannot easily calibrate these thermometers as they dont have a huge range.