The water based thermometer was an invention by Joe. The marks are really close together and are out of order due to the fact that water is less dense when it freezes. It is normally 73 degrees. If it's really cold, it's 72 degrees and of it's very hot, the thermometer displays 74 degrees. Joe has a water-based thermometer and checks it every day but has to go downstairs to ask Mr. Know because it is really inaccurate.