"The bombes were adapted, by Turing and Welchman and others, from a design dreamed up by Polish cryptanalysts. They consist of rotating drums that test many possible Enigma keys with great speed. I’m sure the Prof will explain it to you. But the point is that they have these vast pegboards in the back, like telephone switchboards, and some of our girls have the job of putting the right pegs into the right holes and wiring the things up every day. Requires good eyesight, careful attention, and height."