Question: The person who described evaporation comes from a country with a great wall. How tall is that wall?

<P0-S0> One of the most striking sections of the Ming Great Wall is where it climbs extremely steep slopes in Jinshanling. <P0-S1> Wangjinglou (t 望京樓, s 望京楼, Wàngjīng Lóu) is one of Jinshanling's 67 watchtowers, 980 m (3,220 ft) above sea level. <P0-S2> Southeast of Jinshanling is the Mutianyu Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for 2.25 km (1.40 mi). <P0-S3> It is connected with Juyongguan Pass to the west and Gubeikou to the east. <P0-S4> There it runs 11 km (7 mi) long, ranges from 5 to 8 m (16 ft 5 in to 26 ft 3 in) in height, and 6 m (19 ft 8 in) across the bottom, narrowing up to 5 m (16 ft 5 in) across the top. <P0-S5> This section was one of the first to be renovated following the turmoil of the Cultural Revolution. <SEP> <P1-S0> Han-era astronomers adopted a geocentric model of the universe, theorizing that it was shaped like a sphere surrounding the earth in the center. <P1-S1> They assumed that the Sun, Moon, and planets were spherical and not disc-shaped. <P1-S2> They also thought that the illumination of the Moon and planets was caused by sunlight, that lunar eclipses occurred when the Earth obstructed sunlight falling onto the Moon, and that a solar eclipse occurred when the Moon obstructed sunlight from reaching the Earth. <P1-S3> Although others disagreed with his model, Wang Chong accurately described the water cycle of the evaporation of water into clouds. <SEP> <P2-S0> This book contained many theories involving early sciences of astronomy and meteorology, and Wang Chong was even the first in Chinese history to mention the use of the square-pallet chain pump, which became common in irrigation and public works in China thereafter. <P2-S1> Wang Chong (; 27 – c. 100 AD), courtesy name Zhongren (仲任), was a Chinese meteorologist, astronomer, and philosopher active during the Han Dynasty. <P2-S2> He developed a rational, secular, naturalistic and mechanistic account of the world and of human beings and gave a materialistic explanation of the origin of the universe. <P2-S3> His main work was the "Lunheng" (論衡, "Critical Essays"). <P2-S4> Wang also accurately described the process of the water cycle. <SEP> <P3-S0> the great wall of china is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east - to - west line across the historical northern borders of china to protect the chinese states and empires against the raids and invasions of the various nomadic groups of the eurasian steppe. <P3-S1> several walls were being built as early as the 7th century bc; these, later joined together and made bigger and stronger, are collectively referred to as the great wall. <P3-S2> especially famous is the wall built in 220 -- 206 bc by qin shi huang, the first emperor of china. <P3-S3> little of that wall remains. <P3-S4> the great wall has been rebuilt, maintained, and enhanced over various dynasties; the majority of the existing wall is from the ming dynasty (1368 -- 1644). <SEP> <P4-S0> worldwide prosperity changed dramatically with the onset of the great depression in 1929. the wall street crash of 1929 served to punctuate the end of the previous era, as the great depression set in. <P4-S1> the great depression was a worldwide economic downturn starting in most places in 1929 and ending at different times in the 1930s or early 1940s for different countries. <P4-S2> it was the largest and most important economic depression in the 20th century, and is used in the 21st century as an example of how far the world's economy can fall.