The Day the Universe Changed - James Burke [92]
The instrument-maker, whose name was James Watt and who, incidentally, was a Dissenter, saw that the cold water was keeping the cylinder at too low a temperature, causing the steam to condense too early. Black’s theory explained why. In Watt’s words:
I perceived that, to make the best use of steam, it was necessary, first, that the cylinder should be maintained always as hot as the steam which entered it; and secondly that when the steam was condensed the water of which it was composed… should be cooled down to 100 degrees, or lower…. early in 1765 [after Black’s discovery] it occurred to me that if a communication were opened between a cylinder containing steam, and another vessel which was exhausted of air… the steam would immediately rush into the empty vessel… and if that vessel were kept very cool… more steam would continue to enter until the whole was condensed.
Thus was born the idea of the separate condenser. This was a cylinder immersed in cold water, into which the hot steam from the main cylinder would be introduced through a connecting pipe. In this way the cold water would condense the steam and form a vacuum in both the condenser and the main cylinder while allowing the latter to remain hot, thus the steam could be used more effectively to produce more power with a consequent saving in fuel costs.
In 1765 Watt obtained a patent for ‘A New Method of Lessening the Consumption of Steam and Fuel in Fire Engines’, the term ‘fire engine’ being used because the device was driven by burning fuel. Watt, unfortunately, had no money with which to develop his idea, until Black introduced him to John Roebuck, a Dissenter industrialist interested in draining mines. Roebuck put up two-thirds of the money needed and an experimental engine was built in the grounds of his house. In 1773 Roebuck went bankrupt and his share in the patent was taken over by Matthew Boulton, owner of the metal works in Birmingham. Boulton had met Watt during the latter’s trip to London and he badly needed a source of power for his water-starved premises at Soho.
The machine that changed the world: Watt’s steam engine. The sun and planet gearing can be seen on the drive wheel axle, right. Bottom centre, under water, is the separate condenser. Above it to the left is the main piston attached to the shaft.
In 1775 he and Watt applied to Parliament and were granted an extension to Watt’s patent until 1800. Wilkinson’s cannon-boring system now became useful because with it Watt’s engines could be made with enough precision for the cylinders to be almost airtight. As a result the engines used one-third the fuel burned in any other engine. Everybody wanted one.
The new engine worked well for draining mines, but the real demand for it lay in the factories. Here, however, the need was for an engine that would provide rotary motion, whereas Watt’s piston could move only up and down. In 1781 one of Watt’s assistants, a certain William Murdock, developed a gearing system, known as the ‘sun and planet’ because of the orbiting movement of the driving cogwheel, which enabled the steam engine to be used to run factory machinery. Belts connected the driving wheel to shafts set above the machines in the factory, with other belts running from the shafts down to the machines. In this way steam could power the same machinery that had been driven by the waterwheel. One year after the 1781