# “How do I use a Galileo thermometer?”

As you can see, our storm glass still isn’t back to normal after all the experimenting we’ve been doing on it. So I decided that this would be the week The Nine-Year-Old and I finally learn to use the Galileo thermometer Daddyo gave us all those years ago.

Let’s start with the basics.

**“How do I read a Galileo thermometer?” **

This is the easy part. To read a Galileo thermometer, look at the bubbles floating near the top of the tube. The label on the lowest bubble tells you the temperature.

As I type this, the label on my lowest floating bubble reads 24°C.

Aye, there’s the rub.

All the labels on our Galileo thermometer are written in Celsius. (Front and back, sadly.)

We live in a Fahrenheit world here at Caterpickles Central, so 24°C doesn’t really mean much to us.

**“How do I convert temperatures from Celsius to Fahrenheit?”**

These days, the absolute easiest way to convert from Celsius to Fahrenheit is to Google it. There are entire web pages devoted to eliminating that little bit of math from our lives.

But here at Caterpickles, we believe that the easiest road isn’t always the best road, even when Math is involved, so here’s the math behind those temperature conversion tools.

To convert from Celsius to Fahrenheit, you multiply the temperature by 9, then divide by 5, and add 32.*

In Math-speak, that’s

(°C × ^{9}/_{5}) + 32 = °F

***Fun Fact: **To convert from Fahrenheit to Celsius, you do the reverse. First subtract 32, then multiple by 5, then divide by 9. Or, if you prefer the math:

(°F − 32) x ^{5}/_{9} = °C

Clear as mud? Let’s do a sample problem.

**If the Galileo thermometer reports a temperature of 24°C in Mommyo’s office, what is the temperature in Fahrenheit? **

**Step 1:** Multiply by 9.

**24°C** x 9 = 216

**Step 2:** Divide the result by 5.

216 / 5 = 43.2

**Step 3:** Add 32.

43.2 + 32 = **75.2°F**

75.2°F feels about right, actually.

**The Nine-Year-Old, sadly: “Mommyo, do I really have to do all that math every time I want to use the Galileo thermometer?”**

Mommyo, hard-heartedly: “Yes. Or you could learn to think in Celsius.”

The Nine-Year-Old: “But no one speaks it here.”

Mommyo: “Tell you what. Let’s do all the math one time and use it to make a chart. We’ll keep that chart next to our Galileo thermometer so that we can know what all the labels mean.”

The Nine-Year-Old, grudgingly: “Oh all right. But you have to do all the even-numbered ones.”

Mommyo, pointedly: “They are all even numbers.”

The Nine-Year-Old, factually: “You’re the one who wants to use this thing.”

So much for integrating math into our daily lives.

Here’s our chart, in case you’d like to skip all that pesky math as well:

**The Nine-Year-Old, curiously: “Mommyo, how does the Galileo thermometer know what temperature it is, anyway?”**

That, my little Caterpickle, is a question for next week. Who knows? We might even do a bit of experimenting to see if the theory actually works.

**Related Links: **

- How to read a Galileo thermometer (Office Playground Blog)
- Conversion of Temperature (Math is Fun)

## One Response to

““How do I use a Galileo thermometer?””[…] many weeks for a toddler to count ago, I promised you that we’d talk about how a Galileo thermometer actually works. I fully intended to answer this question at the time, but somehow kept finding one reason or […]

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