Searching for Arrowsmith correspondence

Search for material on Aaron Arrowsmith is turning up surprisingly little about his maps, especially early maps. I'm starting to wonder if he might have corresponded with friend Ambros von Amman. Did they have Map producer's conferences? Amman did order a state of the art sextant or astrolabe (don't recall which) but it came from England. And he corresponded with leading scholars in Germany. What a find that would be? I smell research trip. Any body out there willing to sponsor? My employer won't pay, keeping me on contract only.