Maybe a bit of info here from an 1890 advert:

http://books.google.com/books?id=2J4LAAA...lin&f=false

He was at Berlin SW 12, Friedrichstrase 212 and it appears to state he had humble beginnings and in a very short time he was on top of the world. I guess ole Georg Knaak penned this himself.

The firm was at Berlin SW 12, Friedrichstrase 213 in 1893/1894.

In 1907 the firm sells it all and guarantees it all:
http://books.google.com/books?id=1FEsAAA...lin&f=false

In 1907/1908 the address of the firm is Berlin SW 48, Freidrichstrae 240-241.

By 1920 the address of the firm is Berlin SW 48, Freidrichstrase 15, where the firm was till at least 1925.

Kind Regards,

Raimey
rse