I’ve always known that sewing machines do not mimic hand sewing at all. Instead of using one thread which is pulled through the cloth at the end of the needle, sewing machines use two threads, one of which is plunged through the cloth using a hole at the tip of the needle. But I could never quite visualise how this was done.
I found this picture on the front page of Wikimedia Commons tonight, while I was looking for a picture of Thomas Hobbes and his Leviathan.
Now if someone could just explain the Michelson-Morley experiment to me I would be happy.