Chris, my French is "limited" to say the least, but Hermann Weissenborn did not make the first hollowneck Hawaiian guitars, it was Chris Knutsen, another immigrant luthier (from Norway). If you haven't got the Knutsen book (lots of Weissenborns in there too) I recommend it:
http://elderly.com/books/items/531-1.htm
Bonne journée!
Fred