Okay, this is not for homework, just curious. I was at a friends this weekend and he had a Galileo temperature gauge. I was trying to figure it out. It is full of glass bubbles that are half full of liquid, some small, some large, with glass weights at the bottom and markers. As the temperature rises the liquid in the oval bubbles becomes less dense. Heres my first question: If the liquid becomes less dense what causes it to fall? My belief from placing it near the fire place and watching it, is that as the volume of the liquid increases it compresses the air or gas in the bubble making it less bouyant. (The liquid actually rises to above the halfway mark when hot) Will someone set me on the correct path? My second question: I noticed that the bubbles were different sizes. And that they fall at different temperatures. Are the bubbles filled with different liquids that react at different temperatures, or are the weights of the bubbles different with the same liquid. I know this is an elementary question, but I sure would appreciate any answers to appease my curiousity. Thanks a ton.