what is a cape horn measure? From chapter 3

From what I can tell of the quote, it means a full glass of alcohol,

"Though true cylinders without --within, the villanous green goggling

glasses deceitfully tapered downwards to a cheating bottom. Parallel

meridians rudely pecked into the glass, surround these footpads' goblets.

Fill to this mark, and your charge is but a penny; to this a penny more;

and so on to the full glass --the Cape Horn measure, which you may gulp down

for a shilling."