By 1685 Thomas Newcomen had established himself as an ironmonger in his hometown, Dartmouth. Some of his biggest customers were the mine owners in Cornwall, who faced considerable difficulties with flooding, as the mines became progressively deeper. The standard methods to remove the water - manual pumping, or teams of horses hauling buckets on a rope - were slow and expensive, and they sought an alternative.
Contemporary engines worked by using condensed steam to make a vacuum, but whereas Thomas Savery's pump had just used the vacuum to pull the water up, Newcomen created his vacuum inside a cylinder and used it to pull down a piston. He then used a lever to transfer the force to the pump shaft that went down the mine: it was the first practical engine to use a piston in a cylinder. Casting the cylinders and getting the pistons to fit was pushing the limit of existing technology, so Newcomen deliberately made the piston marginally smaller than the cylinder and sealed the gap with a ring of wet leather or rope.
His first working engine was installed at a coalmine in Staffordshire in 1712. It had a cylinder 21 inches in diameter and nearly eight feet long, and it worked at twelve strokes a minute, raising ten gallons of water from a depth of 156 feet; approximately 5.5 horse power. The engines were rugged and reliable and worked day and night, but were less than one per cent efficient, used a lot of coal, and consequently were first installed in coalmines.
In 1714 Newcomen engines were extremely expensive, costing around £1 000, but nevertheless were phenomenally successful and were manufactured for more than a hundred years. One engine in Pentich was still operating 127 years after installation, and another was being used in Barnsley until 1934.
By the time Thomas Newcomen died in 1729 there were at least one hundred of his engines working in Britain and across Europe. However, he did not die a wealthy man: Savery's original patent of 1698 had been extended until 1733, and covered all engines that raised water by fire. As a result Newcomen was forced to go into partnership with him and does not appear to have benefited greatly from his invention.