Practical arithmetick. [electronic resource] : In four books, I. Of whole numbers, weights, and measures. II. Fractions, vulgar and decimal. III. Mercantile arithmetick. IV. Extractions, progressions, logarithms, &c. extracted from the larger entire treatise, carried on by subscription, and adapted to the commerce of Ireland, as well as that of Great Britain. For the use of schools. By John Gough. Carefully revised, with many additions in the various rules, not in any former edition; By Robert Telfair, of the belfast academy. To which is added, an appendix of algebra, By William Atkinson, late teacher of mathematicks, and now corrected by his son, William Atkinson, mathematician in Belfast.