SPOILER wrote:There's a depressed-looking guy in the Aridell inn. Talk to the innkeeper about him, then talk to him. He'll tell you about antique sextant that he lost. Find it and give it back to him and he'll offer to train you in Cartography.
Best use of skill books as far as I can tell is either to use them to get a whole new skill, saving three skill points, or use it with skills that are above level 5. At least for skills that you can train for money, since 5 seems to be the limit.