In the C18th and early C18th men working with steam engines were always at risk from exploding boilers. In the first steam-driven locomotives it was only the driver, stoker, and anyone having the misfortune to be passing by at the time who would be killed.  But when high-pressure steam boilers started [...]]]>

Stirling engine

In the C18th and early C18th men working with steam engines were always at risk from exploding boilers. In the first steam-driven locomotives it was only the driver, stoker, and anyone having the misfortune to be passing by at the time who would be killed.  But when high-pressure steam boilers started being used in ships – driving side-mounted paddlewheels in American river steamers – the death toll shot up into the hundreds.

While work continued on trying to improve the quality of metal and strength of the seals used in constructing high-pressure steam boilers, one man had been exploring a radical alternative.

Born in Scotland in October 1790, Robert Stirling was one of eight children. His grandfather, Michael Stirling had invented the first rotary threshing machine in 1756, and it was probably from him that Robert inherited his interest in engineering. After a classical education at Edinburgh University, Robert was ordained as a minister of the Church of Scotland in 1816.  This same year he patented his first ‘air’ engine.

There had been earlier experiments with ‘hot-air’ engines both in France and England, so the idea wasn’t new.   What made Stirling’s engine different was his invention of a regenerator, which stored the heat from one cycle for use in the next, making the engine far more efficient.

His engine was a closed-cycle engine which meant the same air – first heated then cooled – was used over and over again. No new air was drawn in and none was expelled as exhaust.

How it works:  air inside the cylinder is heated by an outside source, a small wood or coal fire. This heated air expands and pushes up the piston. The air then passes through the regenerator (which absorbs and stores some of the heat for the next cycle) to the cold side of the engine where it cools and contracts, pulling the piston down.  This continual heating and cooling of the air produces the pressure change that pushes and pulls the piston, making the engine run.

It’s beautifully simple, efficient and clean.  But most important of all because there is no boiler, it’s totally safe.  In 1818 one of these engines was used as a quarry pump and ran for two years.

Heavy investment in high-pressure steam meant that the air engine – an invention ahead of its time – remained little more than a curiosity.

But it gave me a great idea for a book.

(More recently NASA has been exploring the potential of solar-powered  Stirling engines in space exploration.  Submarines powered by these engines are also looking ever more possible.)

Because my books are set in C19th Cornwall, finding a subject and background that hasn’t already been explored by others or myself is not easy. But while I was re-reading a history of the packet service based in Falmouth, one line triggered a light-bulb moment. It mentioned trials of a [...]]]>

steam-driven beam engine

Because my books are set in C19th Cornwall, finding a subject and background that hasn’t already been explored by others or myself is not easy. But while I was re-reading a history of the packet service based in Falmouth, one line triggered a light-bulb moment. It mentioned trials of a new high-pressure boiler fitted to one of the first steam driven packet ships.

For over fifty years the Post Office had run the packet service at a profit, with ships sailing to all parts of the globe carrying mail, bullion, passengers, and despatches to naval vessels. But the end of the wars with France threw scores of naval commanders and crews out of work.  To give them employment and ensure the country would have trained men available in the event of another conflict, the Admiralty pressured the government to transfer responsibility for the packet service to them.  Almost immediately it started losing money.  Instead of continuing to use locally built schooners that were fast, light, and able to cope with most wind conditions, the Admiralty insisted on replacing them with naval brigs. These were cumbersome and top-heavy.  In fact so many were lost during bad weather they became known as coffin brigs.

Desperate to get back into profit, knowing they needed faster voyages and a faster turnaround, the Admiralty decided to experiment with steam-driven ships.  But initial trials were jeopardised by confusion and resistance. The engineers were civilians with no rank and therefore no authority, while the ex-naval commanders and crew of the brigs knew nothing about engines and had no interest in learning.

Early steam-driven marine engines powered paddlewheels fitted on either side of the ship. The Americans were ahead of Britain with this technology and were already using paddlewheel steamers to carry passengers and freight along the Mississippi and other rivers.

But rivers are smooth. The sea isn’t. Paddlewheels digging into ocean waves at different times and different depths resulted in a jerky waddling motion that made all but the strongest horribly seasick.

Another drawback to high pressure steam was that without regular careful maintenance the boilers had a tendency to explode. When this happened in a railway locomotive, only the driver and stoker perished.  But when a paddle steamer carrying two or three hundred people blew apart the loss and carnage were devastating.

This set me thinking. Might there be a safer alternative? I found one. It’s amazing, and I’ll tell you more about it next time.

May the roof above never fall in. May we below never fall out.

A Celtic Blessing:

May you have - Walls for the wind And a roof for the rain, And drinks bedside the fire Laughter to cheer you And those you love near you, [...]]]> A Celtic grace:

May the roof above
never fall in.
May we below
never fall out.

A Celtic Blessing:

May you have -
Walls for the wind
And a roof for the rain,
And drinks bedside the fire
Laughter to cheer you
And those you love near you,
And all that your heart may desire

An Old Wedding Blessing:

May God be with you and bless you.
May you see your children’s children.
May you be poor in misfortune, rich in blessings.
May you know nothing but happiness
From  this day forward

Fisherman’s prayer:

Dear God, be good to me;
The sea is so wide,
And my boat is so small.

Old English Blessing:

May your joys be as sweet as spring flowers that grow.
As bright as a fire when winter winds blow,
As countless as leaves that float down in the fall,
As serene as the love that keeps watch over us all.

Armenian blessing:

May their joys be as deep as the ocean
And their misfortunes as light as the foam.

It has been said that the Brison Rocks, pictured here and lying a short distance off Cape Cornwall, look like General De Gaulle lying in a bath – an accurate  if unflattering observation.

The cycle trail runs between two [...]]]> These are two photos I took recently during a bike ride with Himself along the Carnon Valley cycle trail.   You’ll have heard the old saying:  Kissing’s out of season when the gorse is out of bloom? Well, our mild Cornish climate means that gorse blooms all year round.

The cycle trail runs between two lakes. This is the larger.  Stop for a few minutes and you’ll glimpse  quite large fish as well as darting shoals of smaller ones.

The cycle trail runs right across Cornwall from the Carnon river in the east to Portreath on the West coast.  The first half is mostly level as it follows the old railway track. But then it starts to get really hilly so we’ve only managed to get half way.  We’re building up to the final push. The knees need time to adjust!