"The Jones Live-Map Meter of 1909 used a speedometer cable from a front wheel to operate a set of clock gears that slowly turned a ten-inch interchangeable disk beneath a pointer. Precise road directions were printed on each disk, and as the car traveled and the disk turned, specific commands – “turn left,” for example, or “veer right around the barn” – would be indicated by the pointer, providing the driver with the necessary information at just the right place along the road. Disks were available for many routes in the East and cost ten cents each. Combining parts of different routes meant stopping the car and changing and realigning disks, something that was trouble enough that the Live-Map Meter soon disappeared."
From “The Lincoln Highway – Main Street Across America” by Drake Hokanson. University of Iowa Press, 1988
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