This fascinating, functional instrument is the point at which science meets art. Four hundred years ago Galileo discovered that specifically weighted bubbles would predictably rise or sink in a liquid as the temperature of that liquid changed. These decroative glass reproductions of Galileo's discovery have glass floats precisely weighted in .006 gram increments suspended in a clear, enviromentally safe, nontoxic liquid. Simply read the tag on the lowest floating bubble to determine the temperature.