At various times and places throughout history, it’s been difficult to get your hands on whatever passed for “official” money. It could have been because there just wasn’t any such thing at the time, or because there just wasn’t a means for manufacturing whatever it was supposed to be — often, but not always, metal coins. Regardless of that, if somebody did some work for you, they still expected to be paid.
Centuries ago in Scotland, for example, a landowner might be sufficiently well-off to afford servants, but might need to pay them in something other than coins because coins were in such short supply. Then, of course, the question arises: how to measure the payment to make it fair? According to An Institute of the Law of Scotland, published in 1768, it was done this way: “The sequels are the small parcels of corn or meal given as a fee to the servants,..they pass by the name of..bannock, and lock, or gowpen.”
This is not particularly helpful nowadays until you investigate what the heck it’s talking about. A “bannock” is either a flatbread or the amount of grain needed to make one. And a “gowpen” is an obscure word from Old Norse — it probably arrived in England along with ancient Viking colonists — meaning a handful. Originally the singular “gowpen” meant one handful, and the plural “gowpens” meant a double handful, which was measured as the most you could hold by cupping your two hands together. It helped to have large hands, obviously. But eventually both the plural form and the “single handful” passed out of usage, and “gowpen” came to mean a double handful.
There’s an old Scottish proverb that goes: “A hanfu’ o’ trade is worth a gowpen o’ gold.” According to Michael Quinion, who unearthed it, it means “knowledge, when you’re making a trade, is worth a lot of money.” “Gowpen” can be found elsewhere as well; Sir Walter Scott’s The Black Dwarf mentions it: “A bag was suspended in the mill for David Ritchie’s benefit; and those who were carrying home a melder of meal, seldom failed to add a gowpen to the alms-bag of the deformed cripple.”
As for the reference to “lock” in that book about Scottish laws, I can’t find any reference that makes sense of it. They could also have mentioned payment in “yepsens” — that’s the same thing as a “gowpen;” the only real difference is that “yepsin” comes form Old English instead of Old Norse. “Yepsin” is just as obsolete as “gowpen,” but a bit more amusing because every single citation in the Oxford English Dictionary — and there are at least a dozen — spells it differently.
