The Numbers
Calculators that show their working
Each one prints its formula and the documents and rows of the log it rests on. Where a figure is the book's own arithmetic, it says so. Where it is a placeholder waiting for a document to be read, it says that too. Change a number and everything follows.
Annual salt
How much salt a household and its animals eat, cure and brine with in a year, and what it costs in beech to boil it out of a weak brine.
…
The working
The quantities are document 125's model as Chapter 11 prints it. The fuel is the book's own arithmetic: 2.6 MJ to boil off a kilogram of water, a pan that uses 30 per cent of the heat, 15 MJ in a kilogram of air-dry beech.
Ground for a household
How much ground a household needs at the book's yields: the arable in the five-block rotation, the clover ley, the coppice, and the grass if the cow is the household's own and not the village's.
…
The working
Chapter 18's reconciliation: a hectare and a half of the household's own ground feeds four, a cow needs 2.7 ha of grass, the coppice another hectare and a half. Raising or lowering the area by soil points, against Brandenburg's 35, is a placeholder until a yield table replaces it.
Rests on Documents 117 118 123 25 · rows J15 G13 · Chapter 18, Chapter 8, Chapter 1, Chapter 5
Firewood for the house
Heat, hot water, cooking and the canning kettle for a year, in kilograms of air-dry beech and in hectares of coppice.
…
The working
Chapter 1's house of 116 m²: 11,600 kWh of heat, 3,200 for hot water and 800 for cooking, met by 7,689 kg of beech from a hectare and a half of coppice. A house insulated to the post-2009 standard needs a third of the heat. Steel stoves lose about half their heat where a masonry stove keeps 85 per cent of it.
Rests on Documents 119 123 · rows H24 H25 H26 H30 · Chapter 1
Room for the harvest
The cellar, the grain bin and the smokehouse a household's year needs, counted by mouths.
…
The working
Document 126's volumes for a family of four, as Chapter 12 prints them: a root cellar of 7 m³, a grain bin of 0.85 m³ and a smokehouse of 6.3 m³. Sizing the smokehouse by the pigs is a placeholder.
Rests on Documents 126 64 72 · rows C11 · Chapter 12
Water for house and herd
Litres a day and cubic metres a year for the people, the animals and the garden, against what the roof can catch.
…
The working
Fifty litres a person a day, the WHO's basic measure. The animals' figures are Chapter 18's own and wait on a livestock table. A garden on sand is short of about 300 litres a square metre between May and September. A roof in Brandenburg catches about 480 litres a square metre in a year.
Rests on Documents 122 · rows G46 G47 J30 · Chapter 18, Chapter 5
The village and its trades
How many households before a smith or a cheesemaker can work at the trade full time, and how much ground the village needs on sand.
…
The working
Chapter 18's own village: 75 households, 300 people and about 300 ha with modern seed, 400 with a reserve of forest. At medieval yields, document 131's village of 300 needs about 1,400 ha. A smith wants about 50 households, a cheesemaker 50 to 70.