I see big, from a distance, tall farm silos from time to time. They're for storing grain, right? It makes sense to me (though I don't know that's how they actually work) that you would put the grain in at the top of the tall silo and take the grain out at the bottom. As I understand it, silos have been around for hundreds of years. Before there was electricity or other modern machinery, how did they get the grain to the top of the silo to fill it up?