This is a typical small workshop office, a family brass foundery. The slant top desk is where the Ledger sat. The ledger is a book that holds a record of all of the transactions for the business.
The term ledger stems from the English dialect forms liggen or leggen, meaning “to lie or lay”. Indeed, in some businesses it did lie. However, in the true spirit of the word, it means the book that is open and lays flat and remains in one place.
Flat grave markers are also called ledgers. So now you know.