Where do you live? Try the Gazetteers if you can find any for that time period. They aren't easy to find and sometimes won't let you make copies. I haven't checked Clayton Public Library in Houston, but at the Texas Bldg, Down town Houston Public Library they had five books several years ago. Have you ran his name through THE NEW HANDBOOK OF TEXAS? Have you gone to rootsweb.com and genweb to check the counties that surround the county where you have documented R.R. GILBERT LAST?