Rabdologiae, sev nvmerationis per virgulas libri dvo
John Napier(1550-1617)
 This is the earliest known attempt at the invention of a calculating machine. Napir described a method of multiplication and division by utilizing ivory rods commonly known as ‘Napir’s bones’ and also by means of metal plates which rotated inside a box. He clearly anticipated the invention of the slide-rule by Gunter in 1620.