This is primarily a collection of Sowerby's financial accounts, covering fascicles supplied to subscribers, publishers, booksellers; drawings and engravings prepared for scientific authors and organizations; payments to printers, binders, illustrators (including other Sowerbys), and assistants; and personal expenses. It includes charts of fascicles of "English Botany," "Mineral Conchology," and "English Fungi."

The collection also contains a notebook kept by Sowerby's youngest sister Felicia (financial accounts 1831-1833, drawings, memos); a catalogue of a naturalist's library circa 1830; a list of expenses of and subscribers to 3 "Conversazioni" 1836-1837; and a notebook containing sketches and a few memos.

Authorship: These books are not signed. Although the bookseller attributes them to James de Carle Sowerby, the family was large and busy. However, all the account-books (except MS B134, MS B141, and MS B156) show entries which lead from one to another.

The ledgers are the largest group: they resemble each other, and cover 1831-1865; they include accounts with all the important family members but James de Carle Sowerby, and his son James (who died in 1834). Therefore the ledgers probably were kept by James de Carle Sowerby (who had succeeded his father as head of the family in 1822). MS B134 is a volume for an "Account between J.D.C. Sowerby & C.E. Sowerby" where the account is with "C.E. Sowerby Dr"; therefore it was kept by "J.D.C." and only JDCS has those initials. (Handwriting of the Ledgers varies internally, but the mixture seems consistent from volume to volume.)

MS B141 (accounts, memos, sketches) is not signed and appears to have been kept by a woman (or by a man doing a woman's errands). One account page is headed "Charlotte Dr- to FEAS". Felicia Elizabeth Ann Sowerby is JDCS's youngest sister; no other Sowerby initials fit.

MSS B138-B140 are unsigned and in various hands. MS B140 resembles MS B141. MS B138 has been corrected by "C.E.S." in pencil. These three notebooks are probably by one Sowerby or another.