Raimey,

this is the first time I've heard of Otto Bock in Bonn! Of course he was in Berlin... This must be a mix-up, or is there an inscription on the barrels?
Well, I'm not the youngest anymore, but I'm not that old that I could have met Otto Bock either...
No. (Numero)was the usual abbreviation in the past, today one uses mostly Nr. for number.

Waidmannsheil,
Wolfgang