Pneumatic

he Automatic Temperature Control System was named as a Historic Mechanical Engineering Landmark in 2008. Warren S. Johnson came up with the idea for automatic temperature control while teaching at Normal School in Whitewater, Wisconsin in the 1880's. Originally, janitors would have to enter each classroom to determine if it was too hot or cold and then adjust the dampers in the basement accordingly. Johnson sought a way to end, or at least minimize the classroom interruptions of the janitors and increase the comfort level of the students.

Spearheaded by Hugh Cooper, the Keokuk Dam & Power Plant served as a prototype for many future power plants. The project harnessed the hydropower of the Mississippi River, between Keokuk, Iowa and Hamilton, Illinois.

The crest of the dam is nearly a mile long. The dam structure features 119 arch spans between six-foot-thick piers and a 110-foot-wide pneumatic lock. Combined with the lock, the dam reduced travel time for steamboats by nearly two hours.