I've been using a digital thermometer but today i saw that it wasn't acting right. When i came in after taking care of the chickens i saw it was at 117 degrees farnheight!! i looked at the one with mercury in it and it read 100 degrees. So which one should i trust. I'm leaning towards the mercury one because they are what has been used for along time and the digital one was free. Please help. I'm on day 5 of incubation, felt like 30 days.