E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Throwing the thirteens about. A thirteen is an Irish shilling, which, prior to 1825, was worth 13 pence, and many years after that date, although reduced to the English standard, went by the name of thirteens. When Members of Parliament were chaired after their election, it was by no means unusual to carry a bag or two of thirteens, and scatter the money amongst the crowd.