This might help. http://www.catholic-doc.org This is the website for the Roman Catholic Diocese of SC. There is an Archives page with information on their holdings and research information. Mary Giles is the archivist and I believe her e-mail address is on this page. You should have no trouble getting the records of someone married in the Cathedral c. 1870. I have been able to find records of my family in the very early 1800s as well as been able to go through original record books of some of the Roman Catholic churches in Charleston. linda mhoose@sc.rr.com