Dear Bill, We, too, have a Galilean Thermometer, and it is an absolute delight to us. When I got it, I placed it on a shelf in our living room, temporarily, on its way to my office. However, my wife won't let it leave the living room.
Ours is a Celsius thermometer with a range from 16��C to 28��C with enough spheres for 2��C steps; its outer diameter is 50�mm and it is 430�mm high. We bought it at a local pharmacy, here in Geelong, and thermometers calibrated in Celsius were the only ones available -- there were no Fahrenheit thermometers. Our Galilean Thermometer was supplied by a Melbourne company, Landmark Concepts, and it is labelled 'Made in China'. In our living room we also have an inside/outside electronic thermometer and (within the limits of the Galilean Thermometer's precision of 2��C intervals) our Galilean Thermometer seems to be reasonably accurate. I would like to install a Galilean Thermometer in every Physics lecture room and laboratory -- just for looking at and musing on. It not only indicates the temperature, there is a lot of optics happening in a cylinder filled with liquid and spheres. Cheers, Pat Naughtin LCAMS Geelong, Australia -- on 25/2/04 3:45 AM, Bill Hooper at [EMAIL PROTECTED] wrote: > I have always thought that I would like to have a Galilean thermometer, > because of it's historical significance and its interesting style. But, > in the US, one can only find them which register in degrees Fahrenheit. > I would want one in Celsius. > > (If you are unfamiliar with this type of thermometer, I will describe > it in some detail in a PS, below.) Clearly, the Galilean thermometer > cannot be either "dual labeled" or "switchable" for reading in either > Celsius or Fahrenheit. I'm not even sure if I would call it an analog > or a digital device; perhaps it would be classified as a hybrid. > > While in Europe on a recent trip, I found Galilean thermometers in gift > shops in several towns along the Danube, from Nurnberg to Vienna. No > doubt they are available elsewhere but they happened to be more > abundant in this area which is noted for it's decorative glass pieces > (of which the Galilean thermometer is certainly one). > > Much to my annoyance, I discovered that ALL the Galilean thermometers > in the shops were constructed to show Fahrenheit temperature! Clearly, > the shops were in business primarily to sell souvenirs to American > tourists. > > But I figured, "This is Europe! Surely they must have some of these > things in Celsius for the European visitors." So I asked and, with just > a little disruption (because the shop was very busy), someone was sent > down the street to the shop where these things were made and stored and > a Celsius version was brought to me. I was delighted and bought it. It > now sits prominently in my living room. > > Regards, > Bill Hooper > > PS Description of Galilean thermometers. > > The Galilean thermometer consists of a vertical tube filled with a > clear fluid (water?). In this fluid are several small glass globes. The > globes contain air and a small amount of fluid (water?) which is > colored. The fluid is a different color is in each little globe, which > adds to the thermometer's beauty as well as its utility. > > The air-water combination in each globe is adjusted so that the globes > just barely float (have neutral buoyancy) in the fluid of the main > tube. But the density of the fluid of the main tube is temperature > dependent (like all fluids, of course). That means that, if the globes > are exactly neutral buoyancy at some specific temperature, then they > will float up to the top if the actual temperature is a little cooler > and settle down to the bottom if the temperature is a little warmer. > > In the Galilean thermometer, each of the several little globes is > adjusted to float at a different temperature; and each globe is labeled > with that temperature. In use, one merely needs to notice which is the > lowest of the floating globes to determine the surrounding temperature > (assuming the thermometer is in equilibrium with its surroundings). > > My Galilean thermometer registers the temperature in the range from 18 > �C to 26 �C in steps of 2 �C. That's not a wide range and it is not > very precise. Clearly it is more a work of art than a scientific > instrument.
