Newcomen steam pump
Going back to the very beginning, we look at the first engines
Anybody who has dug a trench more than a few feet deep will have found the obvious problem: Water.
Even in the arid heat of the Arabian desert water is never far away, and it presents real problems for the construction industry, with money and fuel having to be factored in to builds where ‘dewatering plant’ – stationary pump engines – workaround the clock pumping black water into giant tanks.
However, before engines had been invented, there were no pumps to speak of, other than hand cranked ones. This seriously limited the burgeoning construction industry in Europe, but of more drastic consequence was the level of water in quarries and mines. Seams of coal, for example could not be mined very deeply due to flooding and no coal meant no industrial revolution.
So it took one inventor named Thomas Savery way back in 1702, built an ‘engine for raising water by fire’ it was a sort of pulseometer engine, with no pistons or moving parts other than the taps.
It was also useless – the demo model blew up while on show, leaving spectators with singed eyebrows, probably, and a subsequent version in a mine ‘could not be brought to answer’ and also blew up. Savery left the world with two important inventions though – the steam engine, which he patented, and the term ‘horsepower’.
It was up to a chap called Thomas Newcomen to build a new pump, this time with a piston. The device was what would be known as a ‘beam engine’, with the main rod pivoting on a wide bar.
The way forward was to provide as Savery had done, a boiler capable of assuring a continuous supply of steam to the cylinder, provide the vacuum power stroke by condensing the steam, and once that had done its work to dispose of the condensed water.
On the machine, completed in 1712, the power piston was hung by chains from the end of a rocking beam. Unlike Savery’s device, pumping was entirely mechanical, the work of the steam engine being to lift a weighted rod slung from the opposite extremity of the rocking beam.
The rod descended the mine shaft by gravity and drove a force pump, or pole pump (or most often a gang of two) inside the mineshaft. The suction stroke of the pump was only for the length of the upward (priming) stroke, there consequently was no longer the 30’ restriction of a vacuum pump and water could be forced up a column from far greater depths.
Making all this work needed the skill of a practical engineer; furthermore Newcomen was by trade an “ironmonger” or metal merchant which would also have given him valuable access to a variety of practical know-how regarding materials resistance etc.. The boiler supplied the steam at extremely low pressure and was at first located immediately beneath the power cylinder, but could also be placed behind a separating wall with a connecting steam pipe.
The inventor had to pay to use Savery’s patent, but the machine worked superbly with hundreds of units being put into operation over the next seventy years, until being superseded by more modern designs, some of which we’ll look at next month.
Newcomen’s machine was almost comically inefficient – only around one per cent of the heat was turned into useful energy. Being able to clear mines and trenches of water quickly, it was easy to get at the fuel literally, to light the spark and lay the foundations of the Industrial Revolution.