Science and technology of the Tang dynasty
The inventor Ding Huan (fl. 180 AD) of the Han dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered. In 747, Emperor Xuanzong had a "Cool Hall" built in the imperial palace, which the "Tang Yulin" (唐語林) describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song dynasty, written sources mentioned the air conditioning rotary fan as even more widely used.
African Americans
A few other notable examples include the first successful open heart surgery, performed by Dr. Daniel Hale Williams, and the air conditioner, patented by Frederick McKinley Jones. Dr. Mark Dean holds three of the original nine patents on the computer on which all PCs are based. More current contributors include Otis Boykin, whose inventions included several novel methods for manufacturing electrical components that found use in applications such as guided missile systems and computers, and Colonel Frederick Gregory, who was not only the first black astronaut pilot but the person who redesigned the cockpits for the last three space shuttles. Gregory was also on the team that pioneered the microwave instrumentation landing system.