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(b)
Figure 4.1 (b) Watt steam engine. In the Newcomen engine, evaporation of water into the steam chamber
under the piston pushed the piston up. Liquid water squirted into the chamber recondensed the vapor,
creating a vacuum to pull the piston back down. In the Watt engine, evaporation and condensation occurred in
separate chambers, and motions were circular instead of up and down. From Brewster (1832),
www.uh.edu/engines/epi69.htm and www.uh.edu/engines/watt2.gif.
stayed warm due to the boiling of water under it. In
1769, Watt patented this revised steam engine, which
had double the efficiency of the previous one.
Watt made further modifications until 1800, includ-
ing an engine in which the steam was supplied to both
sides of the piston and an engine in which motions
were circular instead of up and down (Figure 4.1b).
Watt's engines were used not only to pump water out of
mines, but also to provide energy for paper, iron, flour,
cotton, and steel mills; distilleries; canals; waterworks;
and locomotives. For many of these uses, steam engines
were located in urban areas, thus increasing urban air
pollution. Pollution became particularly severe because,
although Watt had improved the steam engine, it still
captured only 5 percent of the energy it used by 1800
(McNeill, 2000). Because the steam engine was a large,
centralized source of energy, it was responsible for the
shift from the artisan shop to the factory system of
industrial production during the Industrial Revolution
of 1760 to 1880 (Rosenberg and Birdzell, 1986).
In the nineteenth century, the steam engine was used
not only in Great Britain, but also in many other coun-
tries, providing a new source of energy and pollu-
tion. The steam engine played a large part in a hun-
dredfold global increase in coal combustion between
1800 and 1900. Industries centered on coal burning
arose in the United States, Belgium, Germany, Russia,
Japan, India, South Africa, and Australia, among other
nations.
Pollution problems in Great Britain worsened not
only because of steam engine emissions, but also
because of coal combustion in furnaces and boilers
and chemical combustion in factories. Between 1800
and 1900, the death rate due to air pollution in Great
Britain may have been four to seven times that world-
wide (Clapp, 1994).
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