An informal unit of volume for beer used in many Australian pubs. A middy is generally 285 milliliters (or 10 British fluid ounces), larger than a pony but smaller than a schooner
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}