Copper sheathing<span> is a practice of protecting a under-water hull of a ship or boat from the corrosive effects of salt water and bio fouling through the use of </span>copper<span> plates affixed to the outside of the hull.
It was pioneered and developed by the Royal Navy during the 18th century.
Hope this helps.</span>
During the Cultural Revolution, bourgeois intellectual were sent to re-education camps to be taught in a communist ideology. Many of them were teachers and professors in charge of the education of the common people. But their ideology didn't match the communist one, so they were sent to these camps to be taught how was like to be a peasant or a common person who had to work hard to survive. This movement despised intellectual labor and valued hand labor.
At this time period, people were looking for jobs in factories so they flocked to the cities where factories were becoming popular.
