The American tutor's assistant, improved : or, A compendious system of decimal, practical arithmetic; comprising the usual methods of calculation, with the addition of federal money, and other decimals, dispersed through the several rules of that useful science. Adapted for the easy and regular instruction of youth in the United States. Compiled by Zechariah [i.e., Zachariah] Jess, schoolmaster in Wilmington. - Jess, Zachariah. (Printed and sold by Bonsal and Niles. Also sold at their book-store, no. 173, Market-Street, Baltimore, 1799)