I have recently been acquiring some old railroad negatives off ebay. They are 120 negatives and are obviously from varying photographers, who, I have no idea. I know I can make prints from these which I plan to do, but do I now own the rights to do whatever I want with these negatives? Can I make and sell prints? Can I make prints are display them in a public exhibition? And if so, do I have to state 'photographer unknown'?

I'm just very unfamiliar with this. It is new territory for me.