NAPIER, John (1550-1617). Rabdologiae, seu numerationis per virgulas libri duo. Edinburgh: Andrew Hart, 1617.
12o (143 x 81 mm). Final blank preserved. 4 folding engraved tables, engraved and woodcut text diagrams (one folding plate with repaired tear). (Repaired tear on G2.) 17th-century mottled calf, gilt-ruled on covers, spine tooled in compartments (slightly rubbed, some mottling peeling); blue morocco folding case. Provenance: William Cowan (bookplate).
FIRST EDITION. Napier's most famous accomplishment was his invention of logarithms (first published in his Mirifici logarithmorum canonis description, 1614), which reduced complex mathematical operations to the simpler ones of addition, subtraction, multiplication, and division. (Napier's invention had an immediate and revolutionary impact on the scientific world, and led to the invention of the slide rule, though this device did not achieve wide popularity until the end of the nineteenth century when its use was taught in engineering schools.) Seeking to ease his own difficulties in calculating logarithmic tables, and impatient with the tedious and error-prone process of working with large numbers, Napier devised several mechanical methods of simplifying and speeding up multiplication, the most famous being the rods known as "Napier's bones," each engraved with a table of multiples of a particular digit. He published an account of these in Book I of his Rabdologiae, the title of which Napier derived from the Greek rhabdos (rod); incidentally, this section of Napier's work also contains the first printed reference to the decimal point. Book II of the Rabdologiae "offers forty-seven pages of tables, examples, and general problems demonstrating the utility of the rods in solving questions of geometry and mechanics" (Rider 1990, xii); Book III is an appendix on Napier's promptuary, a more elaborate calculating device consisting of engraved rods and strips; and Book IV, devoted to "local arithmetic," contains one of the first explorations of binary arithmetic as a computation aid. Napier's promptuary has been called the first attempt at the invention of a calculating machine (Hawkins 1988). The only seventeenth-century example of the promptuary extant is preserved at Madrid's Museo Arqueologico; it is described in Tomash 1988. Dibner Heralds of Science 107; Norman 1574; Origins of Cyberspace 11.