"I was thinking upon the engine at the time, and had gone as far as the herd's house, when the idea came into my mind that as steam was an elastic body it would rush into a vacuum, and if a communication were made between the cylinder and an exhausted vessel it would rush into it, and might be there condensed without cooling the cylinder."
- James Watt as recollected to Robert Hart
In January 1769, James Watt received a patent for a steam engine, and with that, he ushered in the Industrial Revolution. Like many great inventions, the concept of a steam engine had been around a long time before James Watt designed his engine. It took Watt, though, to transform the concept into a practical and efficient means of power.
The earliest record of anyone thinking about the use of steam in a practical manner is by the Greek scientist Ctesibius in the 3rd century BCE. None of Ctesibius's writings have survived so much of what we know about his work is referenced by later authors. He investigated the properties of compressed air and its use in different types of pumps. He wrote a treatise on the science of pneumatics, and he is credited with inventing a device that is considered the precursor of the pipe organ.
Later on the Roman engineer Vitruvius (80 BCE - 15 CE) described a device called an aeolipile. (Vitruvius also described the ideal proportions of the human body - the so-called Vitruvian Man.) An aeolipile, named after the Greek god of the wind Aeolus, has an empty round or cylindrical vessel that is able to rotate. The vessel has two opposing nozzles. This is connected to a second container filled with water. The water is boiled to produce steam, and the pressurized steam fills the rotating vessel. The steam is expelled from the nozzles, and the different directions of the nozzles create rotational spin or torque. It is unclear whether Vitruvius intended any practical application of this device, but it seems he did use it to demonstrate the properties of weather. Hero of Alexandria (10 CE - 70 CE) is often given credit for the invention of the aeolipile, and it is sometimes called Hero's Engine. Whereas Vivtruvius just described the device, Hero gives detailed instructions on how to construct it. In the end, the aeolipile appears to have been simply what we would call an amusing gadget or "party trick".
One of the first true attempts at applying steam power to solve a practical problem occurred in the late 17th century. Thomas Savery was a British military engineer who had an interest in inventions. He recognized that flooded mines were a significant problem, and he set about designing a device to pump water out of the mines. In 1698, he received a patent for what was called a "fire engine". The device utilized a vacuum to draw water into a separate container, and then steam pressure would force the water upward. The engine had very few moving parts and had valves to control the pumping. For the machine to operate efficiently, everything needed to be tightly sealed. Unfortunately, the technology of the time period did not allow for this, and the pumps were prone to explosions. It also wasted a lot of fuel, and it could only pump water upward to around thirty feet. All of this made the pump impractical for deep mines. For all these reasons, Savery's "fire engine" was not widely accepted by the mining industry.
Savery's initial patent was for 14 years, but in 1699, an act of Parliament extended the time period to 21 years. The patent wording was so broad, though, anyone else who contemplated developing a steam engine had to either pay Savery or make him a partner. One of these people was Thomas Newcomen. Savery had hired Newcomen as a blacksmith to forge the parts needed for Savery's pump. Savery allowed Newcomen to tinker with the original design. Newcomen ended up developing the atmospheric engine. This would be the first practical fuel-burning engine.
Newcomen decided to draw upon the earlier work on pistons by fellow Englishman, the French-born Denis Papin.
He changed out one of the containers for a piston. A vacuum would pull the piston down while pressurized steam would push the piston upward. The piston was then attached to one end of a beam balanced on a fulcrum point. Attached to the other end was a chain that would then run down to the bottom of a mine and connect to a pump. When the piston moved down, water filled the pump, and then as the piston is pushed upward, the weight of the machinery expels the water. It was more efficient and more reliable than Savery's own engine. The atmospheric engine became successful and adopted throughout England. It was not only used in mines but proved effective in draining wetlands. Newcomen, though, had to share the spotlight with Savery. The original patent outlived them both.
The downside of Newcomen's engine was that after each piston stroke, the steam had to cool and then be re-heated. It took the Scotsman James Watt to solve this problem and forever change the course of human progress.
Watt was working as an instrument maker at the University of Glasgow when, in 1763, he was tasked with repairing a Newcomen engine. In doing so, Watt noted how inefficient the machine operated. By his own account, during a Sunday walk in 1765, he hit upon the idea of creating a separate condenser. The next day he tested his idea with a makeshift piston and condenser. It took him another eleven years to create a working prototype. He would introduce his final design in 1776.
In Watt's design, steam is drawn into the cylinder below the piston. The steam pushes the piston upward. When the piston reaches the top, the steam inlet valve closes and another valve opens. The lower pressure in the condenser allows the steam to enter the separate container and cool. External air pressure then pushes the piston downward. The cylinder always remains hot and the condenser is always cool. This separation inhibits large amounts of heat to escape and be wasted. In this way, Watt was able to increase the efficiency of the Newcomen engine by nearly 75%. A simple modification resulted in a technological revolution.
Watt went into partnership with Matthew Boulton, a successful British manufacturer. Together, through the last quarter of the 18th century, they installed hundreds of the Boulton & Watt steam engine. Watt would retire in 1800 but continue to tinker with other inventions, many of which would never be patented. He also developed the concept of horsepower as a means of measuring the output of engines. The watt as a unit of measurement of power was named after him.
It isn't an understatement to say that Watt's steam engine was a transformative moment in human history. A mode of power that did not rely on human or animal labor opened the door for industry, mass production, and new modes of transportation. Steam power paved the way for the internal combustion engine and the jet engine. The growth of industry, the migration to cities, and the expansion of markets brought about major changes in society. No longer would the West be an agrarian-based society. The explosion of invention and technology through the course of the 19th century would result in the West advancing far ahead of the rest of the world.
Further reading: