Mr Colin Carlin, of Bath, England, has written an excellent essay, "The
Pittsburgh Carlins and the Huguenot Connection," describing the history
of Carlins of Huguenot ancestry. It's quite well-written. Even if you
are not descended from this particular Carlin line, I'm sure you'll find
this most interesting; I strongly recommend that you take a look at it.
The URL is
http://www.carlinarchives.com/history-huguenots.htm .
Fred