doubling within 20 years of that (1870). This coal allowed Britain to turn
the globe pink. The prosperity that came to England and Wales was re-
flected in a century of unprecedented population growth:

population England

Eventually other countries got in on the act too as the Revolution spread.
Figure 1.6 shows British coal production and world coal production on
the same scale as figure 1.5, sliding the window of history 50 years later.
British coal production peaked in 1910, but meanwhile world coal produc-
tion continued to double every 20 years. It’s difficult to show the history
of coal production on a single graph. To show what happened in the next
50 years on the same scale, the book would need to be one metre tall! To
cope with this difficulty, we can either scale down the vertical axis:

population world

or we can squish the vertical axis in a non-uniform way, so that small quan-
tities and large quantities can be seen at the same time on a single graph. A
good way to squish the axis is called a logarithmic scale, and that’s what
I’ve used in the bottom two graphs of figure 1.7 (p9). On a logarithmic
scale, all ten-fold increases (from 1 to 10, from 10 to 100, from 100 to 1000)
are represented by equal distances on the page. On a logarithmic scale, a
quantity that grows at a constant percentage per year (which is called “ex-
ponential growth”) looks like a straight line. Logarithmic graphs are great

UK and world coal production
Figure 1.6. What happened next. The history of UK coal production and world coal production from 1650 to 1960, on the same scale as figure 1.5.