Hi Sim,
This is a great piece of work! I'm familiar with Paul Vernon's White Dwarf articles and remember experiencing something of a revalation at the time I read it. In particular, that fantasy worlds don't have to be realistc, but should be internally consistent. Furthermore you need to have a sense of what is "ordinary" to know what counts as "fantastic".
Spookily I had considered posting something similar myself, though much more closely based on Paul Vernons original. We've come to some of the same conclusions in a roundabout way.
Anyone not interested should stop reading here, but these are my (badly organized) notes:
Medieval Settings
The original medieval coin was the silver penny. A silver penny weighs 1.555 grams (0.05 oz., literally a pennyweight), therefore approx. 640 coins (1000/1.555) weigh one kg. The Troy Pound weighed 240 pennyweights or 373.2 grams.
The mark was the standard unit of account, and was valued at 13 shillings & 4 pence, i.e. 160 pence. 160*1.555g=248.8g, so 4 marks of silver weighs c.1Kg, and 1Kg of silver is worth (160*4) 640 silver pence.
Poor quality lodging, food and drink costs 3CP per day. (MRQII p75, Legend p.111.) This could be inflated to 4CP per day to survive in a city where prices would be higher.
If we propose that the bare minimum funds necessary to survive in a city is 1 silver penny per day then we can value our penny at 4CP. This conveniently gives us values for a ha’penny (2CP) and a farthing (1CP). It also gives us a value for a kg of silver: 640*4CP=2560CP. The value of gold was fixed at around 12 times that of silver throughout the middle ages (hence a shilling is 12 silver pennies).
The continental Silver Penny was the denier. The silver in these coins is about half the purity of English coins, and consequently only worth half as much. (2CP). A copper coin called an obole was worth a half denier (1CP).
1 English penny (1d, or 4CP) is the minimum cost of food and lodging sufficient for survival for survival in a city for one day.
1 shilling (1s, or 48CP) notionally represents one week’s earnings for an unskilled labourer or common soldier (about 2d or 8CP per day, if food and board were provided). It represents the approximate relative income of a peasant farmer working 12 hectares of land (one virgate).
A prosperous yeoman farmer working a freehold of one hide of land (48 hectares) earns around 4 shillings per week. Most ordinary craftsmen will earn 2 to 4 shillings per week.
1 crown (5 shillings, or 240CP) represents the costs of a comfortable standard of living for a week.
1 farthing (1CP) = half a dozen eggs = 1 gallon of second rate ale = ½ gallon of first rate ale = quart of good beer = 1/2lb. of cheese = ½ lb butter =2 lb. Of bread =1/2 lb cured meat = 1 lb. Of ordinary dried fruit.
A yard of common cloth represents the product of about a weeks’ labour (carding, spinning, weaving) and costs around 1 shilling (48CP).
Runequest/ Legend
A copper penny is worth 1CP and weighs 4 grams but has negligible intrinsic value.
A silver piece is worth 10CP and is worth its weight in silver at 4g (c.f. Denarius or Obol). The Bible refers to the Roman denarius as a day’s wage for a common labourer. In the first century the denarius weighed around 3.9 g (2.52 pennyweights of silver) or 10.08CP.
A gold crown is worth 200CP and weighs between 4g and 6.5 grams depending on the relative value of gold.
