Modern instruments and methods of calculation : a handbook of the Napier Tercentenary Exhibition (1914)
Horsburg, E. M. (Ellice Martin), Napier Tercentenary Exhibition (1914 : Edinburgh, Scotalnd) · London : G. Bell · leaf 303
market for general sale, but have been designed for thecompanys own use. A ready reckoner is helpful in a certain way, but the idea contemplatedwas to go entirely beyond the scope of it, and at the same time to teacharithmetic by the use of equivalents in all sorts of measures, and to train… … The New RR Machine. The present model, as illustrated, is set upon a desk-table. It has fourdistinct faces, each face showing different sets of equivalents. The operator,by simply pressing a small key, brings the required face opposite him, withthe controlling handles ready for use. Each face of…
