This is the machine that Commander Schoen made, more than a year ago, for breaking the Nipponese cipher called Indigo. Apparently, as of the beginning of 1940, Schoen was a well-adjusted and mentally healthy young man into whose lap was dumped some great big long lists of numbers compiled from intercept stations around the Pacific (perhaps, Waterhouse thinks, Alpha, Bravo, etc.). These numbers were Nipponese messages that had been encrypted somehow—circumstantial evidence suggested that it had been done by some kind of machine. But absolutely nothing was known about the machine: whether it used gears or rotary switches or plugboards, or some combination thereof, or some other kind of mechanism that hadn’t even been thought of by white people yet; how many such mechanisms it did or didn’t use; specific details of how it used them. All that could be said was that these numbers, which seemed completely random, had been transmitted, perhaps even incorrectly. Other than that, Schoen had nothing— nothing —to work on.