In the famous story about Watt and the boiling kettle, he was not the first person to notice that steam could make a lid bounce up and down. As early as the mid-eighteenth century, several hundred Newcomen steam engines were operating across northern and central England. Even now, they were still used in some coal mines.
The greatest flaw of this kind of steam engine was its terrible waste of fuel, which limited it to coal mines with abundant coal and virtually no market for it. Its main purpose was pumping water. England had many shallow coal seams, but they contained a great deal of water, which accumulated in the tunnels and could easily cause mining disasters. Yet that was not even the worst part.
The coal seams held vast quantities of firedamp. It could suffocate people and explode upon contact with fire. Every worker who descended into a mine to extract coal risked his life. Usually, one person served as the "firedamp safety officer," walking at the very front with a candle in hand.
London was already affected by the Atlantic Ocean's warm currents and westerly winds, making its air damp and foggy. Combined with the smoke produced by burning coal, the two earned London its famous nickname: the City of Fog.
When water vapor met cold air, it condensed. The original Newcomen steam engine's boiler was a large copper brewing vessel. Once filled with steam, it sprayed water inside, creating a vacuum. This cooled the cylinder, so before fresh steam could be admitted, the cylinder had to be reheated. Not only was this inefficient, it also caused losses in volume and pressure.
Watt's solution was to place a condensing apparatus in a separate chamber and maintain a vacuum with an air pump, while the working cylinder was kept