Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.
John W. Nystrom (1824-1885) was an American inventor and author known for his contributions to the field of arithmetic and measurement systems. His work on the tonal system proposed a new way of approaching arithmetic, weights, measures, and coins, with a focus on simplicity and efficiency. Nystrom's innovative ideas and inventions, including the Nystrom's Calculator, have left a lasting impact on mathematical practices and calculations.