A traditional measure of liquid volume, dating back to the Middle Ages. A rundlet is a small barrel usually holding 18 wine (U.S.) gallons (roughly 68.1 liters)
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}