Did I possibly mess up this hatch?

[hokankai]

That method works for non-digital thermometers, but digital thermometers' accuracy varies from different temperature ranges. You actually want to calibrate as close to 100 degrees as possible. What I did was get a medical thermometer (just a cheapo one) and tested it on myself to see how accurate it was (should be around 98.6). Then I got a cup of warm water as close to 100 degrees as possible and put both the probe for the digital thermometer and the medical thermometer in the cup. I calibrated the thermometer against what the medical thermometer said.