How can I calibrate a digital thermometer?

[Bobbi Lou]

I'm incubating with a brand new Little Giant 9300. This is my first hatch with it, and so far it's not looking to promising. It's day 22, and out of 48 eggs, four have hatched, one died in progress, and none of the others have shown any interest in beginning to hatch.
I think I've determined that my hygrometer, at least, is not perfect. During lockdown it wouldn't get above 38-40% humidity, unless it decided to jump directly to 90% for a little bit, then back down to 38-40% again. I'm guessing this had something to do with the low hatch rate.
Also, none hatched on day 21, and the ones that have hatched were the ones closest to the heater. I've had the temperate set at 101 the whole time, and the reading has been consistent throughout incubation.
So, I know there's nothing I can do for this batch at this point other than leave the lid on and hope for the best, but what should I do to ensure accurate temperature and humidity for the next batch?

 

[lazy gardener]

What kind of digital thermometer is it? Is it one with a probe that can be immersed in water? My recommendation is for you to buy a digital medical thermometer... like the kind you'd put in your mouth to check your temp. Then, get a bulb type of thermometer that reads in single degrees. I have a Taylor indoor/outdoor one that's easy to read, and fairly accurate. Then, take a cup of water that's about 100*, and use your fever thermometer to check and see if the bulb thermometer reads the same. If the medical reads 100, and the bulb reads 98, you'll know that it's low by 2*. Now, you can put the bulb thermometer in the incubator, and check it against your digital thermometer that you've been using. You'll have to read up on the salt test for the hygrometer. I use a couple of ancient mercury rectal thermometers as my gold standard, and compare everything else to them. They're a pain to use, b/c they have to be shaken down every time used, they're hard to read, and very slow to respond. But the good thing, is that they will tell me a trend towards temps that are too high.

 

[Bobbi Lou]

Thank you! Sounds like a good suggestion. My thermometer/hygrometer consists of a couple of wires coming from the heating element of the incubator, and stapled on the other end to a piece of lightweight plastic, presumable to keep it from falling down between the eggs.
Could you post a link to an example of the types of bulb and medical thermometers you're talking about, just so I know I'm tracking with you? I guess I'm mostly unsure what type of thermometer would read the water temp as well as the incubator temp...
I did read about the salt test, and it sounds fairly simple except the my thermometer/hygrometer is attached, so I would be unable to fully close the bag and get an accurate reading during the test. Is there an alternate way of testing an attached hygrometer?

 

[lazy gardener]

Try these, just for pics of what I mean.
http://www.americanscreeningcorp.co...0w3BI39KUjibVe6xTkLs4K8NG4tUMa6DR5RoCJIvw_wcB

http://www.surgicalshop.com/health-...wVIYgTRdbEYzN4xibcEoVga4K6b7ZnTl09xoCspTw_wcB