I'm working on another free brush set, this time from a 1655 map. It has a unique style I haven't seen before, but (and maybe because of that) I keep running into symbols which are unfamiliar to me. These aren't cartouches, mind, but repeating symbols—so they do hold some meaning beyond decoration. The map doesn't have a legend/key—and looking through other maps from the same book, they didn't either.

So, I'm hoping someone knows of a book/site/place where someone has compiled a database of old symbols with some explanation.

(Signs on Printed Topographical Maps, ca. 1470–ca. 1640 from Catherine Delano-Smith [PDF] was some help, but more a general overview.)

Thanks in advance.