Lord Gray. Some type of correspondence or journal, IIRC.
I finally caught up on the series at the end of last year. I'll re-read it a few times by the time the next book comes out. Rumor has it that it will be the last with Jamie and Clare.
~sigh~
I've posted a link in the Hobbit Hole to an Outlander tour in Scotland. They actually have a tour that goes to locations in the books. Most of the places would be where you'd visit anyway though. :-)
Jamie.....Yummmmmm!