The most striking feature of the engineering quad of my alma mater, Rice University, are the three massive slabs of granite erected on large plinths at its center, each canted at a different angle: 45, 90, and 180 degrees. Less remarked upon, but more significant to my young, impressionable, and romantic mind, was another sculpture, entitled “Energy,” tucked off on the north side of the quad, against the façade of the Abercrombie Laboratory. It depicts, in relief, a biblical figure clad in a loincloth and sporting a majestic beard, pulling beams of light from the sun with his left hand and casting them down to earth with his right – the apotheosis of the engineer. For indeed, virtually all of the energy used by human civilization derives from the sun, in some fashion or another, a revelation which struck me with great force as an undergraduate.
In the eighteenth century, the predominant source of non-animal energy in European society came from falling water – water that had been lifted into the clouds by the warmth of the sun before descending as rain. Watermills were known and used across Eurasia from ancient times – the earliest evidence comes from the third century BCE. At the height of the Roman Empire, engineers developed the technology on a gargantuan scale, as evidenced by the ruins of the Barbegal mill complex in southern France, which consisted of sixteen wheels running in pairs down a steep hillside, all supplied by a large stone aqueduct. However, there is no evidence for widespread use of the waterwheel prior to the middle ages, when they multiplied across the streams of Western Europe by the thousands. The Domesday Book, for example, an eleventh-century royal census of England and Wales, counted over 5,000 mills in the territories claimed by William the Conqueror.
The endless rotation of the wheel was most often applied to the grinding of grain, but mills for the fulling of woolen cloth were also common – they beat the fibers into a firm felt with wooden triphammers controlled by a camshaft. By the later middle ages, however, inventive craftsmen had applied the watermill to nearly every industrial task imaginable, as historian Lynn White, Jr. cataloged:
…mills for tanning or laundering, mills for sawing, for crushing anything from olives to ore, mills for operating the bellows of blast furnaces, the hammers of the forge, or the grindstones to finish and polish weapons and armors, mills for reducing pigments for paint or pulp for paper or the mash for beer, were increasingly to be found all over Europe.
As long as the rains fell and the waters flowed, these machines carried out tasks that in previous ages would have been possible only at the cost of sore muscles, aching joints, and dripping sweat – whether human or animal.
Millwrights developed a variety of techniques over the centuries to adapt the wheel to different circumstances. The vertical “undershot” wheel, with water directed against the bottom of the wheel, served well on streams with a shallow grade but a high flow of water. The “overshot” wheel, on the other hand, which brought water to the top of the wheel where it filled buckets attached to its circumference, worked better for steep, low-volume streams. A trickle too feeble to push an undershot wheel could still fill buckets, if more slowly, and the steep grade made it easier to bring the water to the top of the wheel (although some sort of wooden flume was required to complete the millrace, which, along with the buckets, made the overshot wheel a more complex design). Horizontal wheels, on the other hand, though relatively inefficient, allowed for very simple mill construction. A horizontal wheel under a flour mill built atop the millrace could turn the grinding stone directly, without the need for a lantern gear to translate a vertical rotation into a horizontal one.
Yet for all the variety of its applications, the supply of water power was strictly limited. One could dam mill ponds to even out the flow of water and cut races to bring water directly to the wheel, but a given watercourse could provide a reliable supply of power to only so many mills. Along the Vienne in southwestern France, mills crowded together as densely as twenty per kilometer of water. The congestion of the streams of the Rhine region with waterwheels was likely responsible for the terminal decline of the Atlantic salmon fisheries in those waterways in the later middle ages. As streams reached the saturation point, conflict over control of the water between upstream and downstream millers inevitably ensued. Many important precedents in property law revolved around such disputes. In 1600, for example, in a case came before the King’s Bench in England, the plaintiff had torn down a pair of decrepit fulling mills to replace them with mills to grind grain. In the interval, the defendant rerouted the water supply to his own upstream mills, claiming that the plaintiff had sacrificed his ancient rights to the water (from “time whereof memory”) by tearing down the original mills. The court ruled in favor the plaintiff – concluding that the destruction of the mills themselves did not destroy his right to the watercourse.
Humans had tapped another potent source of energy, of course, since time immemorial – that of fire. Unlike water power, fire could produce heat to warm homes and smelt ores, but could not drive any kind of mechanical process. Wood historically provided most of the fuel supply for both domestic and industrial heating, sometimes supplemented by peat. But Britain stood out for its increasing exploitation of coal from the sixteenth century onward. By 1700, Britons were digging up nearly 3 million tons of it each year, over thirteen times as much as in 1560, although the population of the island as a whole had not even doubled in that time period.
In the course of the eighteenth century, inventors discovered that, when combined, these two elemental forces of fire and water could turn cheap, energy-dense coal into mechanical energy freed from the shackles of topography. Their creation, the steam engine, would transform the world. The industrial revolution — and all it brought in its train, from cheap clothing to regimented factory labor — began under water power but accelerated under a head of steam. Travel, war, and empire would never be the same after the creation of the railroad and the steamship.
Electrical power, too, was a product of steam. Edison set out to “subdivide the light,” scaling down the overpowering glow of electric arc lighting into something that could be used inside the home. But the even more profound long-term effect of the spread of electrical lighting systems was the ability to subdivide the power of a steam engine, and deliver it wherever, and in whatever quantity, one might desire. Steam removed the constraints that tied machinery to a nearby water source; electric power removed the need for any mechanical connection at all between a source of power and its point of use.
Steam power had knock on affects in other areas of technology and science, as well. Throughout the late eighteenth and nineteenth centuries, the heyday of steam, the development of steam engines simultaneously benefited from and stimulated improvements in metallurgy and the science of heat.
This series will survey the history of this “age of steam”, an age that continues, in attenuated form, up to the present day. For despite the predominance of petroleum-based fuels in transportation over the last century, and the increasing pressure in recent decades to shift to steam-free sources of energy like solar and wind, much of our electricity still comes from heating water to make steam. This subject matter marks a departure for this blog, which heretofore has focused on the history of computing and communications technologies. Moreover, there is no shortage of popular accounts of the early history of the steam engine, including the recent Energy by Richard Rhodes and The Most Powerful Idea in the World by William Rosen. However, I believe this series will bring some fresh perspective on the story, especially by extending it into the twentieth century, unlike the many accounts that leave off as soon as the locomotive became a viable means of transport, around 1830.
Evidence for experiments and devices that turned steam into motion date back to the first century BCE, But Not until the philosophers of the seventeenth century developed a science of pressure were inventors able to create the first engines that could drive machinery by steam. We will begin this series in earnest next time by examining the emergence of this science, whose most important result was the revelation that the air itself has weight.
 Nuclear and geothermal power are partial exceptions, deriving as they do from the husks of long-dead suns, rather than from our present one.
 Wind power also played an important role on the open plains of northwestern Europe, but it was generally less reliable than water and had more limited applications.
 Lynn White, Jr., Medieval Technology and Social Change (London: Oxford University Press, 1964), 89.
 H. Lenders, T. Chamuleau, A. Hendriks, et al., “Historical Rise of Waterpower Initiated the Collapse of Salmon Stocks,” Scientific Reports 6, 29269 (2016).
 T. E. Lauer, “The Common Law Background of the Riparian Doctrine,” Missouri Law Review 28, 1 (Winter 1963), 83.