Tisken looks like a dialectal form of Deutschen = German, especially if he was from the South, near Switzerland (where Swiss German is Schweitzer-Tysk, though my spelling might well be off).
Actually, he was born near the Dutch border in Germany. His full name is Tisken an gen Doors. But that's a good idea, being from Deutschen, or maybe from Dutch? (Dietsen?)
This message was edited 9/10/2008, 12:36 PM