Texas State Historical Association
Texas State Historical Association: Science & Health
A collection of articles on science and health topics related to Texas. Includes research using scientific balloons, county health statistics, mineral-water spas, the work of the Southwest Science Institute, science research at...
PBS
Pbs Nova: Estimating Up, Up and How Far Away?
Use this cleaver site to estimate how far away a hot air balloon is from you using your thumb and arm length.