The Rotary Winnowing Fan

The Chinese were about two thousand years ahead of the West in their approach towards the winnowing of grain, the means used to separate out husks and  stalks from the grain after harvest and threshing. The easiest method goes back even before the cultivation of crops:

'The grain is thrown up into the air, preferably in a strong wind, so that the
chaff is blown away while the grain falls down to the ground. Later, winnowing baskets were used, which required dextrous handing. With the right  kind of rhythmic wrist movement, one can separate the heavy grain from the chaff, which is gradually tipped over the edge of the basket, leaving the grain behind. Later still, the winnowing sieve was introduced. By the second century BC, Chinese had invented rotary winnowing fan. Models of them have been found in the ancient tombs, made of pottery and with  miniature working parts.