301 Years of Steam Power

In 1712, Thomas Newcomen erected a steam engine of his own design near Dudley, in the West Midlands of England, thereby kicking off the age of steam. (Yes, this would have made a better post last year, to mark a round 300-year anniversary, but better late than never..)

We were told in the 5th grade that the steam engine had been invented by James Watt after noticing the way that the steam pressure in a teapot could cause the lid to lift a little. A nice story, but (a) James Watt did not invent the steam engine, and (b) early steam engines did not work the way that the teapot story would suggest.

In ancient Greece there were some experiments with the use of steam power to create mechanical motion; thereafter nothing significant happened in this field until the late 1600s, when Thomas Savery invented a device for raising water by steam: it was intended to address the growing problem of removing water from mines. Savery’s invention was conceptually elegant, with no moving parts other than the valves: unfortunately, it could not handle a water lift of more than about 30 feet, which was far insufficient for the very deep mines which were then becoming increasingly common.

Newcomen’s engine filled a cylinder with low-pressure steam, which was then abruptly cooled by the injection of a water jet. This created a partial vacuum, which pulled the piston down with great force–these were called “atmospheric” engines, because the direct motive force came from air pressure, with the role of the steam being simply to create the vacuum when condensed. After the piston reached the bottom of the cylinder, it would be pulled upwards by a counterweight, and the cycle would repeat. (See animation here.)  Conceptually simple, but modern reconstructors have found it quite difficult to get all the details right and build an engine that will actually work.

These engines were extremely inefficient, real coal hogs, requiring about 25 pounds of coal per horsepower per hour. They were employed primarily for water removal at coal mines, where coal was by definition readily available and was relatively cheap. But as the cotton milling industry grew, and good water-power sites to power the machinery became increasingly scarce, Newcomen engines were also employed for that service. For example, in 1783 a cotton mill–complete with a 30-foot waterwheel–was constructed at Shudhill, near Manchester..which seemed odd given that there was no large stream or river there to drive it. The mill entrepreneurs built two storage ponds at different levels, with the waterwheel in between them, and installed a Newcomen engine to recycle the water continuously. The engine was very large–with a cylinder 64 inches in diameter and a stroke of more than 7 feet–and consumed five tons of coal per day.

Despite their tremendous coal consumption and their high first cost, a considerable number of these engines were installed, enough that someone in 1789 referred to the Newcomen and Savery engines in the Manchester area as common old smoaking engines. The alternative to the Newcomen engine described above would have been the use of actual horses–probably at least 100 of them, if my guesstimate of 40 horsepower for this engine is correct. These early engines resembled the mainframe computers of the early 1950s, in that they were bulky, expensive, resource-intensive, and limited in their fields of practical applicability…but, within those fields, absolutely invaluable.

 

The Newcomen era ended when James Watt invented a vastly more efficient version of the steam engine. He had been asked by a professor at Glasgow University to repair a model Newcomen, for the 1763-64 session, and was struck by the inherent inefficiencies of the design. His primary idea, which he realized in the Green of Glasgow where he had “gone to take a walk on a fine Sabbath afternoon”..was the use of an external condenser for the steam, thereby avoiding the necessity of repeatedly and wastefully heating the cylinder up and then cooling it down. Watt’s design brought coal consumption down to around 7 pounds per horsepower-hour, and further improvements over the next century brought it to as low as 3.

Visiting Manchester in 1965, industrial historian Richard Hills saw quite a few reciprocating steam engines still hard at work:

Some engines ran day and night, like those in waterworks or sewage pumping stations. Their task was to pump water up to the top of a watertower, or to an outfall in the sewage system, so the load was almost constant. Water cannot be hurried, so such engines did their duty in a slow stately manner, steadily, day in, day out….Rolling mill engines were exactly the opposite and were the most dramatic to watch in the dark mills with the unearthly glow of the hot metal. The engine would be slowly idling round until the red-hot lump of iron was fed into the rolls. Then the engineman had to open the throttle fully as the rolls gripped the iron and squeezed it out. It looked as easy as squeezing toothpaste out of a tube, but a slight miscalculation on the part of the engineman and the rolls might jam through insufficient power, or the rod of red-hot iron could run amuck all over the rolling floor. Woe betide anyone who was in the way…

Yet, out of all the varied applications of steam power, the most interesting and possibly the most demanding for the engine itself was the textile mill engine. Absolute regularity and dependability were necessary to ensure a constant speed against a varying load for the whole of the working day, week in, week out, year after year…it may be said with considerable justification that the cotton textile industry formed the major growth point of the Industrial Revolution and the history of the cotton textile industry, in England at any rate, coincided with the rise and fall of the rotative steam engine.

Hills describes these engines and the environment in which they operated:

I was amazed at the feeling of power in those thrusting piston rods and yet at the quietness, for most of what little noise there was came from the clicking of the Corliss valve gear. Here was a machine that developed 1200 hp, and yet it was possible to hold a conversation in a normal tone of voice. How different from internal combustion engines.

The enginemen took a pride in their job and kept their charges scrupulously clean…The brasswork was, of course, always gleaming against the black background of the main castings of the cylinders and engine-beds. Part of the floor was paved with colourful mosaic while the lower parts of the walls had decorated glazed tiling. Here was the vital powerhouse for the whole mill. If anything happened to go wrong with that engine, the whole mill stopped and everybody was thrown out of work. Therefore it is not surprising that, on such a vital piece of equipment, so much care was lavished.

The engines that Hills saw in 1965 were not going to be around much longer, at least in their operational roles, but the age of steam is still very much with us. The steam turbine, developed in the late 1800s and  in common use by the 1920s, now generates the major portion of the world’s electricity, including all coal and nuclear plants. Natural gas plants are being built with combined-cycle equipment, in which exhaust heat from a gas turbine is used to boil water or another fluid which then powers a steam turbine. This provides a further gain in efficiency by making use of heat that otherwise would go into the atmosphere or the cooling water.

I’ve frequently seen it asserted that the steam engine caused the Industrial Revolution. This is too strong–Richard Arkwright’s original power-driven spinning machine was, after all, called a Water Frame, reflecting its intended power source. Had the steam engine never been invented, there would still have been an industrial revolution of a sort, but it would have been strictly limited in its scope owing to the limited availability of waterpower sites.

The creation of mass affluence, in America and other countries, has been very largely driven by  the growth of mechanical power, both steam and internal combustion, with a useful but necessarily limited supporting role being played by hydropower. The continuation of mass affluence also depends on the continuing availability of mechanical power.

Richard Hills, in his description of the textile mill engine, noted that it was a machine on which the whole of the mill depended, and that for that reason it was appropriate that much care be lavished upon it.  By analogy, America’s mechanical power infrastructure represents a machine on which the whole of our society depends, and a wise political class would lavish care upon it, or at least refrain from doing it damage, rather than crippling it with policies that are both ignorant and frivolous.

The Richard Hills excerpts are from his interesting and well-written book, Power from Steam: a History of the Stationary Steam Engine.