This is Henry Cheney’s Patent Nail Holding Hammer — which should not be confused with the later Cheney Nailer.
U.S. Patent 116,553 was issued July 4, 1871. This hammer was designed to hold cut nails using the groove cut where the inner edges of the claw meet. This aligns the nail between the claws with the hammer’s center of mass directly behind the head of the nail.
According to a 1902 report in The Iron Age, in South Africa Cheney Hammers were outselling English-made hammers by twelve to one, despite the fact that they were sold for twice the price. The Patent Nail Holder was particularly popular.
Below is the page describing these hammers from the 2003 M-WTCA reprint of the 1904 Henry Cheney Hammer Company Catalog.
The markings on this example match those found on later Cheney Edge Tools which appear to be from the 1917-25 period and possibly later. It’s hard to imagine that they would have continued manufacturing this model after the introduction of the Cheney Nailer in 1927.
