Air conditioning
In 1902, the first modern electrical air conditioning unit was invented by Willis Carrier in Buffalo, New York. After graduating from Cornell University, Carrier found a job at the Buffalo Forge Company. There, he began experimenting with air conditioning as a way to solve an application problem for the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn, New York. The first air conditioner, designed and built in Buffalo by Carrier, began working on 17 July 1902.
William Symington
William Symington quickly saw a way to marry the efficiency of the Watt engine with the simplicity of that devised by Thomas Newcomen. Encouraged by Gilbert Meason, Symington demonstrated the practicality of his idea and his improved atmospheric engine was patented in 1787. When Watt sent someone to make a sketch of how this new engine worked, he discovered that the steam was condensed under a second piston and this was then pushed down when fresh steam entered the cylinder, forcing out the condensate. The power piston worked by the atmospheric pressure acting on the vacuum created by the condensing steam.