The 19th century brought on much economic growth and advancement in accounting in the United States. The teaching of accounting began to veer away from rules and instead sought the logical underpinnings of the system. It was a time when accounting evolved into accountancy through the development of theory, such as the proprietary theory and the theory of two-account series. The Townsend Journal (1840–1841), which chronicles the joint venture between two young men in the Boston maritime trade, is a case study of this progression in commerce and accounting during this pivotal time. B. F. Foster's contemporaneous Boston publications on bookkeeping provide the framework to understand this evolution in accountancy, as well as the recordings in the Townsend Journal. Through the examination of the Townsend Journal alongside B. F. Foster's texts, this paper preserves and illustrates a historical link in the evolution of the field.