ScientificAmerican1894-07-21.jpg Scientific American 1893-04-29ThumbnailsScientific American 1894-09-22Scientific American 1893-04-29ThumbnailsScientific American 1894-09-22Scientific American 1893-04-29ThumbnailsScientific American 1894-09-22Scientific American 1893-04-29ThumbnailsScientific American 1894-09-22Scientific American 1893-04-29ThumbnailsScientific American 1894-09-22
Hardening composite plates for bank vaults by immersion in the Hudson River. hardening to make burglar-proof vaults.



Source: Steve Kirch, collector, and creator of a great website about SCIENTIFIC AMERICAN in the past

Restoration by: magscanner