The tool is a snow knocker or snow hammer.
In the winter, snow and ice can get packed under a horse’s hoof, turning into a solid mass of frozen material. Walking on this can cause tripping and sliding, and even serious injury, so it needs to be removed. Thus this handy little tool.
(From A Museum of Early American Tools by Eric Sloane)
Here’s the team that assisted in the above photo, providing sleigh rides at the Hanford Mills Museum Ice Festival on Saturday, Feb. 4, 2017. It’s a great event–you can actually go out and cut some ice blocks yourself.