Wait a minute - this isn't a harp guitar! 

I know...and yet it is.  Oh, it's not a "true" harp guitar, as they are classified today - but nevertheless one of the legitimate definitions (12 different of which are here).

Ah, well, now, that's a long story, which I recently finished (well...started).  It's called 

The Birth of the American 12-string Guitar

...where you'll read about the original patent, and the various incarnations and Grunewald variations.  It's pretty tedious...don't say I didn't warn you!