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IIRC, Joseph Attwood was an English anvil maker in the late 1800s. His label is stamped upside down to differentiate him from the other Attwood making anvils at the same time.
If you really want...

Cold would be around zero degrees F for an anvil. I think -15F is the coldest temperature that you want to hit cast iron at because of cold embrittlement, but that is assuming you have perfectly...

Cold day, cold anvil, one hit and it shatters like glass. :(