Tale of Two Thermometers

I have been engaging in some reasearch trying to come up with a hoophouse design that didn’t cook my plants during the day and freeze them at night.

To try and assess how well the design works I took two thermometers and placed one outside and one inside.

So far so good. Then I started getting some weird readings…. like off the chart stuff. The two thermometers were different types. (One was a bulb thermometer and one was the spring loaded kind.

Perhaps that was the problem. To get closer to accurate results I went out and bought another bulb type, an exact duplicate of the one I had…. or so I thought.

The readings were better but they still seemed off. Like in the morning when the temp inside the greenhouse was colder than the temp outside!

I thought about it for a day, then I had the idea to put the two thermometers side by side.


Two identical thermometers, made by the same manufacturer and the bulb assemblies were in totally different places!

I went back to the store and started comparing thermometers. To my astonishment, Not only was there no agreement in temperature between different brands of thermometers on the shelf, there wasn’t even agreement between the same manufacturers product!

How maddening is that? To buy two identical measuring devices, bring them home and find they are off by several degrees! Imagine if that were the case with calipers, or tape measures?

Lesson learned, when accuracy is importantin a measuring device, check the product before you leave the store.