This article is devoted to the rediscovery of a document by Israel Abraham Staffel (1814–1885), a prolific Polish inventor. It is a handwritten book in Russian and Polish that provides detailed information about one of the most famous of Staffel’s inventions, a 13-digit arithmometer, honored at the Great London Exhibition in 1851. The brief biography of Staffel, born into a Jewish family of meagre means who became famous in his time as an inventor, and a description of his developments are presented. Particular attention is paid to his mechanical calculating machines. In the Appendix, an English translation of the handwritten book by Staffel appears for the first time. Typical mechanical calculating machines by the end of the nineteenth century were based on Leibniz’s stepped drums. Staffel’s arithmometer was based on pinwheels. The content of the discovered book allows us to raise the question of the influence of Staffel’s invention on the arithmometer’s design. The paper, which also clarifies and complements certain facts about his life, activity and inventions, demonstrates the need for further archival research to confirm the currently accepted history of innovation.