The second page ("Coding in Metal"), illustrating how computations occur using mechanical intrinsics like differentials, is where this gets fascinating.
When my great grandfather was drafted into WWI he was a chemistry professor at Berkeley. They sent him to Annapolis and then he was an ensign. I found a ship's roster last summer helping to clean my grandma's estate. I can't remember his exact job title from the roster, but it seemed clear he was working the target computer.