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.
Charles Thilorier
Adrien-Jean-Pierre Thilorier was an employee of the French Post Office in Paris who invented, among other things, an oil lamp, a gas compressor, and an apparatus for producing liquid carbon dioxide. It was a French scholar who revealed that he had discovered dry ice.