Attention, Pinheads!

For once I have a legitimate question:  anybody know anything about a terne
plate roofing manufacturer named Dunphey-Smith Co?  We have an old
roof--being demo'd as we type--made of small sheets of what appear to be
terne that are marked

                DUNPHEY-SMITH CO.
                IC OLD STYLE
                KEY            STONE
                COPPER BEARING METAL
                5 POUNDS COATING

Please advise.  Pinhead Salutes to all legitimate answers.  The Ken-Ralph
Secret Salute to those who might attempt to mislead.

Old Ralph, back again (a relief to you all)