Was your ancestor an inventor? Did they apply for and receive a patent? There are several databases you can search. Google Patents is the most well known, but there are four others you might want to try out. All are free to search.
To obtain the one-page Quick Sheet pdf for easy reference of where to search for patent documents, you can download it by clicking on 5 Free Ways to Find Patents from Your Inventor Ancestor
For all the previously published Quick Reference Guides, click on QuickSheets.
Good Luck and Happy Hunting!