The beautiful River Dart and an invention which changed the world

During last week's visit to South Devon, we spent a couple of days around the estuary of the River Dart near Kingswear.

Looking down on the coast path just beyond the Dart estuary

Coleton Fishacre, 1920s country retreat of the D'Oyly Carte family

Greenway, holiday home of Agatha Christie and her family

Views of the River Dart from the Greenway Estate

A short ferry ride across the Dart from Kingswear took us to the historic naval town of Dartmouth, where residing in the Visitors' Centre is one of the world's most important inventions.

Dartmouth

I have claimed many times that froth flotation is one of the world's most important technological inventions, certainly since the industrial revolution, but without the invention of the steam engine there would have been no industrial revolution.

The inventor of the first practical steam engine was born in Dartmouth in 1664. Thomas Newcomen will be a name unknown to many but his atmospheric engine allowed water to be pumped from deep below ground, allowing miners to go deeper to access coal and minerals to feed the new industrialised world. Hundreds of Newcomen Engines were constructed through the 18th century.

One of the original Newcomen Engines, at Dartmouth

The engine operated by condensing steam drawn into the cylinder, which was mounted directly on top of the boiler. Steam from the boiler filled the cylinder, replacing the air. The steam was then condensed by injecting cold water into the cylinder, the resulting vacuum then allowing the pressure of the surrounding air to force the piston down to complete the working stroke. On completion of the stroke the weight of the pump rods drew the piston back up the cylinder, ready for the next stroke.

Although the thermal efficiency was only around 0.75% the engine was so sound in principle that it laid a solid foundation on which later engines could be built, as well as performing unchanged in basic concept for over 150 years.

James Watt's later engine design in 1776 was an improved version of the Newcomen engine that roughly doubled fuel efficiency. Many atmospheric engines were converted to the Watt design, for a price based on a fraction of the savings in fuel. As a result, Watt is today better known than Newcomen in relation to the origin of the steam engine. He later realised that Newcomen engine designs wasted a great deal of energy by repeatedly cooling and reheating the cylinder and introduced a design enhancement, the separate condenser, which avoided this waste of energy and radically improved the power, efficiency, and cost-effectiveness of steam engines. In the early 19th century Cornishman Richard Trevithick (posting of 25th April 2015) increased thermal efficiency to around 9% with the high pressure steam engine.

So let's salute these great inventors and remember that steam is still used to generate most of the electrical energy that we use today, whether it be from fossil fuel or nuclear power stations.

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