## Thursday, May 31, 2012

### A Nice Thermometer Dial—tiptoeing onto the metric scale

Most everyone knows that 0° C = 32° F and 100° C = 212° F, and maybe -40° C = -40° F.

But I must admit to just realizing that there are some other easy ones as well. Namely for any temperature T = 10x °C (x a digit), we have F = 18T + 32, which are all whole digits. Thus a nice new few to learn, so we can watch the Canadian weather reports and know what the temperature is... not to mention getting in step with the rest of the world. This dial emphasizes these points.

-40C = -40F
-30C = -22F
-20C = -4F
-10C = -14F
0C = 32F
10C = 50F
20C = 68F
30C = 86F
40C = 104F
50C = 122F

We call this the "Easy Conversion Scale." It has been adopted by Fischer Precision Instruments in German for a few of their products sold in the US

On a related effort to nudge the metric scale more to the front, we have made a pdf version of the scale shown below. Sort of a crafts project. It prints on letter size paper that can be cut vertically to make the tall scale.

A scale like this would be great for a classroom so that the values are upfront for quick reference. Then we can watch the frequent global weather forecasts from NHK (Japan) and France 24 and get a better feeling for global temperatures.