How do you calibrate a glass thermometer?

How do you calibrate a glass thermometer because I need to take a temperature on someone who is not feeling well

Medical glass thermometers do not need to be recalibrated I think. Otherwise, just plop it into warm water with a reference thermometer and see the difference.

Or perhaps you mean how to shake it down? I always take it by the end and swing it quickly from side to side. It's a wrist movement. There's probably youtube videos on it.

I come from the era when glass thermometers were all that was available. With the stem end, opposite the silver bulb, grab onto the end tightly, and shake it down at least a few times. When you look at the line between the numbers, which is the mercury column, it should be below 96 degrees, at least. Now it's ready to be used. Never expose a glass thermometer to warm or hot water. You'll permanently destroy the accuracy. Glass thermometers work great, but they're delicate.

Use multiple thermometers at the same time, and use their average. 😉

How did it go Alex?