Although I am not familiar with 19th century mill ledgers I am someone who has had to read contemporary documents from the early 17th century and decipher them. If you can scan and share the pages in question I would be glad to take a shot at them.
Dale H. Cook, Photographer and researcher of standing mills and mill sites
Mill List Coordinator, The Society for the Preservation of Old Mills
https://plymouthcolony.net/photos/pages/mills.html