Targeted Science

Bimetallic Strip
Bimetallic Strip

Some people believe that targeted science, as done by the Royal Society, has less intellectual merit than the pure pursuit of knowledge. One such thinker was the blue-skies man himself, John Tyndall.

In the 1870s, to an audience in America, he said that behind all our practical applications, there exists a region of intellectual action to which practical men have rarely contributed, but from which they draw all their supplies.

Blue Skies Research

In other words, he knew there is a distinction between blue skies research and applied research, and he also knew which one had more intellectual merit.

As Tyndall saw it, his blue-skies science was far superior. But this simple experiment demonstrates the value of targeted science.

This is what’s called a bimetallic strip. Actually, it’s two of them in parallel. They are called bimetallic strips because one side is brass and the other side is steel. So you’ve got steel, brass, brass, steel. As you can see they are set up parallel to each other. Simple enough. But the value of this device only becomes clear when the temperature changes. If I drop this into some boiling water… then immediately… those strips separate.

The reason for that is that brass expands more than steel when you heat it to a given temperature. Now, if you were a pure blue skies scientist, as Tyndall meant, then what you’d do is you’d say, “Well, that’s interesting. I wonder why that is?” And you’d start investigating things like the atomic structure of the metals to work out why they behave in that way. And that would be all you cared about. Whereas, if you were one of those lesser-applied people, pursuing targeted science .as Tyndall would have it, then you might ask questions such as, “How useful could this be?”. That’s technology, that’s engineering.

Well, the answer turns out to be this is very useful indeed.

John Harrison

So useful, in fact, that the inventor who came up with the bimetallic strip believed it could change the world. He was a man called John Harrison. A man on a quest to solve a highly-specific problem. One that caused a terrible accident in the waters surrounding a small archipelago just off the south-western tip of the Cornish peninsular.

Lifeboat in stormy seas
Lifeboat in stormy seas

These are the Isles of Scilly. On a calm day, they are a haven for tourists and locals who seek out the peace and tranquillity of the waters here. But it’s a different story when the weather is stormy. The Scillies are a complex mixture of jagged rocks in the water and perilous rock-fringed islands. If you get lost here, it’s a graveyard.

On 22 October, 1707, there was a tremendous storm, just at the time when Admiral Sir Cloudesley Shovell was sailing his fleet back from a glorious naval defeat in the South of France.

He wanted to turn east into the English Channel to take the fleet home to Portsmouth. But he was out of position. And what he did was he turned east into the Scilly Isles. His flagship, HMS Association, hit the rocks here at Gillstone. This is an engraving of what it might have looked like. There were 800 men on HMS Association. All of them lost their lives. You can imagine what it would have been like. They would have been smashed against rocks like this. Sir Cloudesley Shovell went down with his men. And three other of the ships also were wrecked. They were swept north by the waves

John Harrison
John Harrison

All in all, somewhere between 1,500 and 2,000 lives were lost on that night. It was the second worst peacetime disaster in British naval history. And all because the fleet had no idea where they were.

Shovell and his men had no precise method, storm or not, to calculate the fleet’s longitude, their position east or west around the Earth. They didn’t stand a chance. But they were by no means the first. For centuries, ocean navigators had struggled to find their longitude and repeatedly, voyages ended in tragedy.

So in 1714, shocked by the loss of Shovell’s men, Parliament demanded a method to find longitude be produced. £20,000 would be paid for the most accurate solution. The Board of Longitude was set up to adjudicate. They were inundated with responses from mathematicians and natural philosophers. But amongst the ideas was a surprising proposal. And it came from Yorkshire-born carpenter John Harrison.

Accurate Longitude

What the board were anticipating was some kind of fundamental geometrical method for measuring longitude, perhaps by looking at the positions of the stars or the phases of the moon. But Harrison had a more practical idea in mind. He knew that if you knew the time in Greenwich from your ship, whereever it was in the world, you could calculate the longitude just by measuring the position of the sun in the sky. The problem was that in the 1700s nobody had built a clock accurately enough to keep time on a long sea voyage. So Harrison decided to build such a clock and thereby claim the prize.

Chronometer H4
Chronometer H4

Producing a clock that remains accurate on a rolling ship is not straightforward. Changing temperatures at sea play havoc with the mechanism, causing the metal components of the clock to expand or contract, varying the speed at which the wheels turn and making the clock either lose or gain time.

So John Harrison invented his bimetallic strip to compensate. As the strip curves to varying degrees, depending on the temperature, it adjusts the timekeepers accordingly and ensures that the clock’s accuracy is maintained, whatever the temperature. Bristling with other John Harrison inventions, like ball bearings which reduced fiction, the clocks worked brilliantly.

25 years after he began, Harrison eventually presented the board with what was essentially a large pocket watch. 13 centimetres in diameter, he called it the H4.

Now, the principle of finding longitude is very simple. All you need to know is the difference in time between noon where you are and noon in Greenwich. What I have to do is watch the sun as it tracks across the sky and look for the time when it reaches its highest point, zenith, that’s noon here. And then I read off that time on a clock that’s been set to Greenwich Mean Time, and that time here in the Isles of Scilly is… about… now. Which is 12:39 and 20 seconds. I can feed that number, 39 minutes and 20 seconds, into a few equations, they’re called the equation of time values, they take account of things like the Earth’s orbit, and out will come my longitude. So my longitude here in the Scilly Isles is 6.29° West of Greenwich.

For its maiden voyage to Jamaica, Harrison’s clock was at sea for two months. Thanks partly to its bimetallic strip, it lost just 5.1 seconds. It was a triumph for John Harrison.

However, John Harrison was quick to learn the real price of financial assistance from the Board of Longitude. The Board were made up of astronomers and they were very much in Tyndall’s camp. They expected that the longitude problem would be solved by some kind of an advance in our fundamental understanding of the universe, a pure solution. So every time John Harrison came along with his rather more applied idea, they rejected it. And it wasn’t until Harrison presented his fifth timepiece that the board almost reluctantly accepted that the problem had been solved, and even then, they didn’t pay him the full prize-money. But the longitude problem had been solved by the British government funding applied science. And, in fact, so accurate is Harrison’s solution that this method was still used for finding the position of ships until the 1970s.

What John Harrison and the longitude story shows is that it isn’t only Tyndall’s blue-skies science that can lead to profoundly important results. If you have a specific problem and you focus time and effort and money on it, then applied science can be equally successful.

John Harrison’s clock marked the beginning of a string of important problems that would be solved by science.

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