The Athol Machine & Foundary Co. name change happened in 1930. They ceased operation in 1963. Your vise was made somewhere in that range. Without pictures, I cannot be anymore specific.
Value is whatever someone will pay for it. Again, without pictures that show condition, wear, repairs, missing parts, etc. there is no way to even guess what someone will pay.
All of that said, if you're here just for valuation, you're better off doing an advanced search on Ebay to see what people paid for the vise that you have.
If you're a tool guy like the rest of us, welcome and enjoy the forum.