I think they're talking specifically about printed maps. I'm not sure the hemispheres have been printed back to back like this. This feature of the map seemed

I think they're talking specifically about printed maps. I'm not sure the hemispheres have been printed back to back like this. This feature of the map seemed particularly unique: "To measure distances from one side to the other, you can use string or measuring tape reaching from one side of the disk to the other, he suggested."