Harry Beck may have created the iconic Tube map, which substituted a schematic diagram of the network for a geographically accurate map, but he didn’t invent the diagrammatic transit map. Alberto Cairo points to a number of pieces that explore examples of diagrammatic maps that were contemporaneous with or earlier than Beck’s work: Asaf Degani’s article in Ergonomics in Design points to the influence of designer F. H. Stingemore (see p. 12); Douglas Rose’s online essay comparing Beck with George Dow; and there’s a 2005 book by Andrew Dow (George’s son), Telling the Passenger Where to Get Off: George Dow and the Evolution of the Railway Diagrammatic Map. None of which is meant to diminish Beck’s achievement (I think), but serves to remind us that no innovation ever occurs in a vacuum. [Kenneth Field]