ScientificAmerican1875-03-06.jpg Scientific American 1875-02-27ThumbnailsScientific American 1875-03-13Scientific American 1875-02-27ThumbnailsScientific American 1875-03-13Scientific American 1875-02-27ThumbnailsScientific American 1875-03-13Scientific American 1875-02-27ThumbnailsScientific American 1875-03-13Scientific American 1875-02-27ThumbnailsScientific American 1875-03-13

Cutting screw threads with a hand chaser.