Charles Watson, a British school teacher in the 1850’s notices he, and his students, are repeatedly getting sick in his classroom. He reasons that the indoor air quality has to be the source of the problem. Using well established principles he designs a non-electric mechanical Syphon Ventilator that introduces healthy air and displaces toxic air in the classroom. The results are far beyond his expectations. He goes on to share his invention with the world, installing over 13,000 ventilators throughout the United Kingdom. His insights and the applied principles are just as relevant today as they were in 1851. Sick buildings make people sick.