many documents exist people have not heard about them.
Not because they don’t exist but because some people have them and want to keep them for themselves.
One day I saw on ebay (if I remember well) a very old book (half in german half in french) about the life of Sellier (or Bellot) and the factory. On the ebay page there were about ten different pages as samples. very interesting
As an idiot I didn’t downloaded the pictures.
When i came back the day after the item had disappeared.
And i never seen again this book or ever heard about it;
Another time I missed original pre 1900 Eley shotshells drawings (not the modern ones we know).
Same story with Italian and French documents.
All the stories (fusion of companies, bombs, flood, civil war, aso) are good as excuses to say documents have disappeared;
This is not true and anybody working in a big company will understand that quickly.
When a company manufactures something, the drawing is not only in the archives of the company. One sample yes of course, but you will find another sample in the manufacturing room, another in the sales office, another one in the quality office, another one in the test office, very often one is sent to the customer and so on.
therefore even if 3/4 of the factory has been destroyed or even if the archives have been destroyed, there is a location where there are still documents.
Therefore it is mathematics.
Any catalogue, factory book, factory drawing, even pre 1900, exist somewhere and somebody has it.