Thursday, September 10, 2015

My Office and a Galileo Thermometer

Well, I have officially survived my first week and a half of being department chair. I figured that I should take a picture of my office before things explode and you can't see the desk anymore.

If you have an eye for detail you will note that I have a Galileo thermometer (the kind made of a sealed glass cylinder filled with a clear liquid and containing several glass balls filled with liquids of varying density) sitting on my desk.

Actually - here is a bigger picture.

The clear liquid in the cylinder in which the bulbs are submerged is usually not water but an organic compound (such as ethanol) the density of which varies with temperature more than water's does (though water does get used in some models).

Each of the sealed glass floats contains either alcohol or water dyed with food coloring  and is of a slightly different density (controlled by controlling the weight of the hang tags actually). For most liquids as temperature increases, the density decreases, thus as the temperature in the room changes, the individual floats will rise or fall in proportion to their respective densities relative to the liquid in the cylinder. 

To read this Galileo thermometer, look at the distribution of the bulbs in the cylinder. If there are some bulbs floating near the top, some clustered at the bottom, and one bulb floating alone in a gap in the middle - the hang tag on that lone bulb tell you the approximate temperature. If there are no bulbs in the gap then average the temperature values of the bulb above and the bulb below the gap to find the approximate temperature. Or with some models you simply look at the tag hanging off of the lowest floating bulb to determine the approximate temperature.

Either way - you will note that all of the bulbs have sunk to the bottom of the cylinder. This means that the room is over 80°. This is actually the first day that the top bulb shows any signs of trying to float. Most of the week and all of last week the bulbs were buried at the bottom of the cylinder. It has been hot in here.

So - that is the downside of having the fancy office with the windows in a place where the A/C is broken. OTOH - I think my plants might like it here.

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