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5.2
THE FORMS OF POWER
It is not necessary for players or GMs to be able to
actually design any device in order to use this portion of
Construct Companion. However some knowledge of the
different types of available motive forces to power proposed
inventions will be helpful in deciding what is
plausible at different technology levels. (… And a 10-
Foot Pole has a broader coverage of technology throughout
history, while the three volumes of Tech Law consider
all aspects of science-fictional technology.)
5.2.1 WATER POWER
Waterwheels have been used for at least twenty-one
centuries. Initially for grinding grain, they later drove
pumps, sawmills, tilt hammers (for forging iron), and
bellows for furnaces and forges. In early water mills, the
rotating wheel with its paddles could be lowered into the
stream. This was connected via a vertical shaft to the
actual grindstone. More efficient designs guided the
incoming water to a point below the waterwheel’s center.
The first cast-iron wheels came into use only in 1776, and
various improvements continued to be made in the 18th
and 19th centuries.
The greatest drawback of waterpower is the need for a
substantial source of water, such as a stream or tidal
waters channeled through millponds. Water-powered
Automata must be limited to large fixed-position machines.
5.2.2 WIND POWER
Wind power has been used to grind grain, pump water
and drain farmland. Hero of Alexandria described a
wind-powered device, which drove a piston pump forcing
air through a wind organ to create sound. Windmills
were built as early as 644 AD by Persian millwrights.
Later designs used large sails with wooden frames that
rotated in response to the wind driving a grindstone via
a set of gears. The mills were supported on a fixed post
such that the whole apparatus could be turned into the
wind. A brake wheel could be used to stop the mill. By the
14th century, windmills had attained their familiar tower
shape with the millstone and gears inside and the sails on
a rotating upper cap. The size of the sails grew to over 60
feet in diameter by the 16th century. Eventually steam
engines overtook wind-power in popularity by the late
18th century.
Wind-power is limited by the need for wind with large
installations required to generate enough power. Windpowered
Automata must be limited to large machines
and sail-powered vehicles.
5.2.3 CLOCKWORK POWER
As described in section 2.1.3, the advent of tempered
steel springs allowed inventors to fashion much smaller
timepieces. Springs are elastic components, which store
energy by being stretched or deflected by a load (as in the
26 CONSTRUCT COMPANION
process of winding up a watch spring). This energy can
be released gradually as motion, which can be transmitted
via a series of gears (moving machine parts) to, say,
turn the hands on a watch. Steady transmission requires
accurately manufactured gears.
As evidenced by history, clockwork is a very practical
power supply for portable devices – most recently clockwork
radios! Wristwatches can normally operate for a
whole day before needing to be rewound. Devices requiring
more energy need larger or better springs or to be
rewound more frequently. Clockwork is possibly the
most versatile premodern power source for Automata of
all sizes and types. Amplifying its energy with magical
assistance is, however, usually essential for larger machines
and vehicles. Artificers should normally substitute
magic for manual propulsion of clockwork Vehicle
Automata as turning propellers and the like will exhaust
crews relatively quickly, limiting the maximum distance
that may be traveled before rest is required.
5.2.4 STEAM POWER
Steam powered the Industrial Revolution. In a steam
engine, water is converted to steam by heating in a boiler.
The steam expands in volume under pressure and this
expansion can be used to drive pistons, which in turn can
be connected to other moving parts. The loss of some of
its heat energy cools the steam such that it condenses
back into water that can be recycled back into the boiler
for the next cycle. Simple steam engines have the steam
expand in only one cylinder; compound steam engines
have multiple cylinders of increasing size with the steam
driving pistons in each as it is forced through them.
Practical use of steam awaited the close of the 17th
century. Thomas Savery built the first steam-powered
pump with hand-operated valves to drain water from
coalmines in 1698. Thomas Newcomen improved the
design in 1712 with the addition of a cylinder fitted with
a piston. James Watt added the condenser in 1765 reducing
the fuel consumption by three-quarters, and then
developed a more complex engine, which rotated a shaft
rather than simply moving a pump up and down. Such
engines were deployed in factories and mills to operate
heavy machinery. Nicholas-Joseph Cugnot built the first
steam carriage in France in 1769, while Richard
Trevithick’s steam locomotive made its first successful
run in Wales in 1804. At sea, William Symington tested
the first steam-powered tug in Scotland in 1802, with
Robert Fulton constructing a passenger steamboat in
America in 1807. Steam engines were used to power
crushing machines and dredges, drive sawmills, roll
iron, and process cotton and tobacco.
Steam engines are bulky and potentially dangerous –
high-pressure jets of superheated steam can scald skin
and sear the lungs if breathed in. Boilers to generate the
steam require lots of fuel to keep boiling the water. Steam
Automata will be noisy, hot, and dirty. To be frank,
mundane steam engines are really too bulky, inefficient,
and fuel-intensive for submarines and airships – they
can be made to work but the range of the vehicles is very
limited. For steam-powered land vehicles and surface