Jim Thompson wrote (message 249312, 2014‑07‑18):
 "Since there is so little info available about Robert Duke chisels, I thought
Ishould post a couple of pictures. The mark is very clear.
https://picasaweb.google.com/102358420595488787966/MysteryTo
ol?authuser=0&feat=directlink
I (Conroy here again) just bought a chisel on eBay with a partly illegible mark.
The photo for the listing is excellent, clearer than the chisel itself was when
I first saw it:
http://www.ebay.com/itm/192259021014

( third photo). From the chisel itself I could make out "Robert," "Cast," and
the triangle; and after thrashing around a bit with "Robert O??", "Robert Dow?",
"Robertson", and so on, I ran it down in the Archive with Jim's crystal-clear
photo and comment. The pleasure of being able to start a message as I did is
incredible, but it doesn't really surprise me. He's still there looking after
us.
Since I'm now an owner with some stake, I'll weigh in on a discussion that
developed later in the thread. It was suggested that this Robert Duke might be a
Robert Duke & Co. that ceased operations in Sydney around 1855.  I'd say: no
way. Look at the typography of the words, thin monoline letters completely
lacking any kind of serif. This isn't a nineteenth century mark, or maybe just
barely before the turn of the century. And the aura of the my chisel, all the
little hints of color and shape, seems American to me. I could be wrong on
"American," but there's no way the typography could be pre-1855. There must have
been two Robert Duke companies, unrelated and probably in different companies.
I chasing Robert Duke I came across a person we ought to know about: William
Metcalf.

https://en.wikipedia.org/wiki/William_Metcalf_(steel)

According to Wikipedia, After "1868 he was engaged continuously in steel
manufacturing, and in 1897 he organized the Braeburn Steel Company, of which he
was the head until his death[in 1909]. He is credited with having made the first
crucible steel in America." This was apparently, according to the "Crucible
Steel" entry, a simpler method than the English Huntsman process, involving
direct melting together of iron and carbon. In any case, the manufacture of cast
steel in America would have brought its price down sharply, and would mark the
point when laminated blades gave way to all-cast-steel blades. Useful dating
indication for a whole range of tools. Maybe others on the list know about
Metcalf, but I didn't.
Tom ConroyBerkeley