Educated as an engineer, he later converted to economics. His machine, first built in 1949, is meant to demonstrate the circularflow of income in an economy.
这个装置是他于1949年首先建造的，旨在论证一个经济体系中收入是如何循环流动的。
2
In a dusty field in Kitui, eastern Kenya, farmers are being taught how to construct small, semi-circular barriers of earth that control the flow of water, slowing its run-off.