July 2, 2013 9:53 am
Three hundred and fifteen years ago today Thomas Savery’s patented the steam engine. His patent included no pictures, simply the following description:
”A new invention for raising of water and occasioning motion to all sorts of mill work by the impellent force of fire, which will be of great use and advantage for drayning mines, serveing townes with water, and for the working of all sorts of mills where they have not the benefitt of water nor constant windes.”
Savery’s patent wasn’t entirely well received at the time. He was a military engineer, and the Surveyor of the Navy wasn’t at all interested in servicemen trying to come up with new ideas. He said of Savery’s patent application, “And have interloping people, that have no concern with us, to do to pretend to contrive or invent things for us?”
Today, Savery’s version of the steam engine is known as the Savery Pump. Here’s how it works, from Michigan State University:
The Savery pump required pressurized steam to force the water upwards. Water could be pushed upwards limited only by pressure of the steam. Savery writes: “my engine at 60, 70, or 80 feet raises a full bore of water with much ease.” The boiler would have needed to hold 35 psig pressure to raise water 80 feet- similar to the pressure in an automobile tire. It is likely that this use of such pressure was a reason that the Savery pump had a reputation for boiler explosions. Zealous operators undoubtedly increased the boiler pressure to pump water upwards further, and thus created some of the accidents by overpressurization.
To make his invention more popular, Savery wrote a little pamphlet called “The Miner’s Friend: or, A Description of an Engine to Raise Water by Fire.” He distributed the pamphlet around mining areas like Cornwall, hoping to get miners to use his pump in their mines. Many miners didn’t take him up on it, however, because they were afraid of the pumps exploding due to over pressurization. Their fears were certainly justified, as steam engine explosions were not uncommon. The book Safety-valves: their history, antecedents, invention and calculations explains:
It is not uncommon for a coroner’s jury, while attempting to ascertain the cause of some disastrous boiler explosion, to be told by the confident witness (he is always on hand in strong force in such occasions) that “the safety valves were all right, as they had been examined an hour before the explosion occurred.”
After Savery, many engineers improved upon the steam engine design, to give us things like trains and steam-powered ships. And the steam engine chugs along today, with steam turbines generating about 80 percent of the power we use on Earth.
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