I found this amusing passage in a Kane novel:
“Have you, say, twenty-five mesitsi gold [about two hundred dollars]?” Arbas asked casually. The stranger faked a hesitant pause–no merit in giving the assassin reason to think to ask for more. “I can raise it.”
-Karl Edward Wagner – Darkness Weaves
I don’t know why, but I find the exchange-rate note charming. It also matches with my intuition that buying a 10-GP sword is approximately the same scale of professional expense as, say, buying an $80 electric drill. (Of course, 200 dollars in 1978, when the novel was written, is probably more like $600 in 2012.)
Oddly, I’ve been noticing a lot of specific expenses in books lately, which I can use to construct a tenuous web of currency equality.
This man used to work in the baths for a daily wage of five dirhams. For Dau’ al-Makan he would spend every day one dirham on sugar, rosewater, violet sherbet and willow-flower water, while for another dirham he would buy chickens.
-Tales of 1,001 Nights
According to D20SRD, “the typical daily wage for laborers, porters, cooks, maids, and other menial workers” is 3 SP, which is not too far from the bath man’s 5 dirhams. Let’s say that a dirham is equal to an SP, and the furnace man’s high pay is because Cairo happens to have a strong economy. After all, says 1001 Nights, Cairo’s “soil is gold; its river is a wonder; its women are houris; its houses are palaces; its climate is mild; and its scent surpasses that of frankincense, which it puts to shame.”
D20SRD is silent on the price of willow-flower water, but a chicken is 2 CP. That means that the bath worker and his wife eat five chickens a day! That seems high to me, but the story goes on to say that, when a guest stays with them, they feed him two chickens a day. So five chickens is plausible!
As a fun bonus, if we take the SRD, Kane, and 1001 Nights as equally valid, we can determine that 10 dirhams = 1 GP = $8 in 1978 = $24 in 2012, and we can infer the important fact that, in 1001 Nights Cairo, a chicken cost 50 cents.
All of this is, of course, nonsense, for many reasons. One of the main reasons is that the US economy is totally incompatible with any historical economy: things used to cost different amounts relative to each other.
Check out this late 19th century letter from Emile Zola to Cezanne:
I’ll reckon out for you what you should spend. A room at 20 francs a month; lunch at 18 sous and dinner at 22, which makes two francs a day, or 60 francs a month.…Then you have the studio to pay for: the Atelier Suisse, one of the least expensive, charges, I think, 10 francs. Add 10 francs for canvas, brushes, colors; that makes 100. So you’ll have 25 francs left for laundry, light, the thousand little needs that turn up.
-Emile Zola via Malcolm Gladwell’s What the Dog Saw
Look at the amounts budgeted for necessities. A starving artist who eats only two meals a day spends three times more on food than on rent. Half of his money is spent on food. That’s almost exactly the reverse of a US budget, where the food budget is typically 1/3 of rent.
That’s why we can’t really convert 25 GP to $200 USD. The modern world is too different from the past. Emile Zola, writing in the 19th century, inhabited a world that was, economically, closer to D&D and 1001 Nights than we are now.