ScientificAmerican1875-04-03.jpg Scientific American 1875-03-27ThumbnailsScientific American 1875-04-10Scientific American 1875-03-27ThumbnailsScientific American 1875-04-10Scientific American 1875-03-27ThumbnailsScientific American 1875-04-10Scientific American 1875-03-27ThumbnailsScientific American 1875-04-10Scientific American 1875-03-27ThumbnailsScientific American 1875-04-10

Saxby and Farmer's system of railway switches and signals. Engraving showing signal house, switches, and signals. Interlocking routing control of railroad trains.