winnowing machine

Thus, then, have the St. Edmundsbury Monks, without express ballot-box or other good winnowing-machine, contrived to accomplish the most important social feat a body of men can do, to winnow out the man that is to govern them […] Ballot-boxes, Reform Bills, winnowing-machines: all these are good, or are not so good; — alas, brethren, how can these, I say, be other than inadequate, be other than failures, melancholy to behold?