The first atmospheric engine
Although little is known of Newcomen activities in the ten years before 1711, it's likely that he spent the time perfecting the world's first practical steam engine — later to be known as an 'atmospheric' engine. He certainly had a workshop at Dartmouth
in Devon, where he and his business partner John Calley
experimented with models and a prototype. The first known Newcomen engine
to work successfully was erected at a Staffordshire colliery in 1711-12.
So, how did he arrive at a workable solution for a stationery steam engine? Newcomen knew that a piston could be driven down a vacuum-filled cylinder by the pressure of the atmosphere alone, as demonstarted by various other experimenters. He sought to harness the potential power of this, which he did using the principle of a see-saw.
If you take a large beam and secure it in the middle, with the piston rod attached to one end and a counterweight to the other, the weight rises as the piston descends. If the weight is a bucket of water, the bucket can be emptied at the top of the stroke, and if this action is repeatable indefinitely, you have an effective pump.
For the pump to work, the cylinder is first filled with steam, fed to it from a boiler. To create the vacuum, the steam has to be condensed. At first (and possibly for some years), to do this Newcomen cooled his cylinder externally using cold water flowing inside a lead casing around the boiler — a very slow process.
According to Swedish engineer Marten Triewald (1691-1747), who later worked with Newcomen, the breakthrough in condensing steam efficiently was a happy accident. The prototype's brass cylinder had a casting fault, which had been repaired with tin solder. After many test cycles, the repair failed and cold water from the cooling jacket squirted into the cylinder through a tiny hole. The steam condensed immediately, producing a vacuum so strong that the piston dropped with enough force to break through the base of the cylinder and smash the lid of the boiler below.
Newcomen amended his prototype so that cold water was injected directly into the cylinder. The strokes were now much quicker and more powerful, though using the engine was laborious as all the valves were operated manually.
Not a man to give up, he continued to refine the engine, eventually solving a number of problems, such as how to prevent air entering the cylinder with the steam, which reduced the vacuum potential, and how to empty the hot condensate from the cylinder. He also found a way to make the steam and water injection valves self-acting.
Being a Devon man, Newcomen knew about the challenges local miners faced in trying to keep the workings dry. In Cornwall, where many of the coastal mines had tunnels extending out under the sea, water was limiting the depth of extraction. Thomas Savery (c.1650-1715) had tried to interest the Cornish miners in his own pump, installing one in 1702, but it couldn't raise water from sufficient depth. He abandoned his attempts in 1705.
In this same year, Newcomen is alleged to have entered into a partnership with Savery. As Savery held the patent for 'fire engines', Newcomen may have decided that his efforts would be better directed at producing engines under that patent rather than trying to initiate a separate one. He was not a wealthy man and may have been daunted by the probable cost of a new patent, including the prospect of contesting Savery's copyright.
It was said that there was one or two of Newcomen's engines in Cornwall by 1710-11. This is unconfirmed, though quite likely. The first of these, apparently fuelled by turf, was at Balcoath Mine near Porkellis in Wendron district, where tin had been quarried mainly from alluvial deposits since 1644. Another engine is mentioned at Wheal Vor (Great Work) tin mine at Breage near Helston.
Newcomen's engine showed how much more work could be done using mechanisation over manual or animal labour. But it was inefficient by modern standards, using huge quantities of coal for a relatively small power output. This made it a very expensive proposition for south west England, where there are no natural coal deposits.
Perhaps then, it's more than chance that the first known successful Newcomen engine
was installed at a colliery, giving it a ready source of cheap (or free) fuel. It was erected (1711-12) at Coneygree Park
or Tipton Field in Staffordshire, near Dudley Castle, and used to pump water from the coal mine at a depth of almost 47m. It worked at 12 strokes per minute. Newcomen and Calley supervised its construction personally.
This engine was soon famous, and English and European visitors were eager to see how it worked. However, the Devon men were reluctant to divulge the details — copying of ideas being difficult to prevent — and Triewald claims that even the Spanish Ambassador to London was denied entry to the engine house.
It wasn't long before Newcomen and Calley were building more engines in the Midlands and further north, and engaging the services of other engineers. Their business was expanding and manufacturing techniques were improving. Success beckoned.
main reference Transactions of the Newcomen Society