If Don Firth was drinking in a UK pub and being sold a pint measuring 16 fluid ounces then he was being severely short-changed, since a pint is 20 fluid ounces.
The old school rhyme is that "A pint of water weighs a pound and a quarter".
BTW a "schooner" is just a tall glass, with no particular quantity. Typically, today, schooner glasses are used for that disgusting beverage they call lager and a smaller version for sherry.

Colyn.