With regard to the preservation of stone, I know that there is a
     specialist who works with the preservation and conservation of
     gravestones.  Her name is Lynette Strangstad.  I know she did some
     work with Historic Charleston on some of their cemeteries after the
     hurricane a few years ago.  I have heard her make presentations at
     conferences on protection measures for stone.  I am not certain of her
     affiliation or how to contact her, however someone on the list may be
     able to advise you.
 
     My other suggestion is that a number of years ago, the National Trust
     for Historic Preservation published a book on masonry.  Perhaps
     someone on their staff could recommend some specialists in the
     preservation of stone.
 
     Liz Crowell