If the person you're looking for happened to die in Philadelphia 1803-1915, the below web site has info on the death certs, which often shows the estimated birth year and/or actual birth date. Hope this helps. Sharon _http://search.labs.familysearch.org/recordsearch/start.html?datestamp=11993 668#c=1320976;p=collectionDetails_ (http://search.labs.familysearch.org/recordsearch/start.html?datestamp=11993668#c=1320976;p=collectionDetails)