The first volume in this set is a Daybook (i.e., entries written down informally in order of occurence).

The following 6 ledgers provide transactions arranged under account-name. Accounts usually one to a folio, sometimes continued on a later folio; some folios show several accounts. Left page shows services performed and material supplied by James de Carle Sowerby; right page shows payments to or material supplied for JDCS.

Names of account-holders are primarily notable geologists and botanists; also surgeons, veterinarians, Sowerbys, engravers, booksellers, and artisans. Some accounts are essentially lists of fascicles sent to the account-holder; some concern making drawings (engraving, coloring, printing, etc.) for the account-holder; some pay artists and artisans for materials or processing. There are also accounts with publishers (primarily Longmans, the Taylors, and Van Voorst) and with scientific societies; some are lists of fossils supplied to or by the account-holder.

The major works which Sowerby himself was issuing in fascicles were "English Botany," "Small English Botany," "English Botany Supplement," "English Fungi," and "Mineral Conchology." These have separate accounts and are also reflected in the other accounts. Accounts with family-members are a web of business and personal relations.

Dates of coverage are tentative. Accounts are continued both elsewhere in the same volume (sometimes on an earlier page) as well as in later volumes; sometimes an entry was added to an account several years after the volume had closed. There are attempts at indexes in most volumes. MSS B129 through B133 lead into each other; MS B129 refers to an earlier book which is not MS B128 (MS B128 overlaps somewhat with MS B129).

There are also four account books (In two-page format, but arranged chronologically, not by name of account-holder. Left page "Received"; right page "Paid." Both business and personal daily expenses.).