Looking back through the history of innovation, the technologies that created the biggest impact are the ones that enabled further innovation. Whether it’s the water wheel, the steam engine, the electric motor or the microchip, each triggered a wave of invention as people figured out how to use them. And technologies build on one another. One of the most powerful developments over hundreds of years has been our increasing ability to accurately and precisely manipulate matter. Precision in measurement, precision in manufacturing, and precision in control.
The precision available to consumers today is astonishing. My hobby is astronomy. As a schoolboy, I dreamt of having my own telescope, but it was an unaffordable dream. Amateur astronomers routinely built their own telescopes from scratch because there were no consumer products. Today, with mass production techniques, Chinese manufacturing capability, and cheap computing, a fully automatic computer-controlled high-quality telescope is a standard consumer item. I have a telescope with capabilities beyond anything that professional astronomers had access to when I was a child; gazing up hopefully at the night sky.
To take photographs through a telescope, you must deal with the annoying fact that stars appear to drift across the night sky at 15° an hour. 360° make a circle, the Earth rotates on its axis in 24 hours, so if you’re standing still on the earth every hour the sky seems to move by 15°. Through a telescope, the stars, nebulae and galaxies are drifting across your field of view all the time. Your telescope must accurately track the movement of the sky and hold the view steady for the long exposures needed for photography.
A friend asked me how good my telescope was at following this movement? So I did a quick back-of-the-envelope calculation. The answer astonished me. Imagine if I was on a soccer pitch with my telescope on one goal line, with somebody holding up a dressmaker’s pin 100 metres away on the other goal line. As they slowly walked from one corner flag to the other, my telescope could keep locked onto that pin with an average pointing error less than the width of the pin. That is for a piece of hobbyist equipment full of motors and gears and bearings and other mechanical bits and pieces. I think that’s a jaw-dropping performance.
It is the same with telescope optics. The mirror in a reflecting telescope must be precisely shaped. Any errors affect performance. When the Hubble Space Telescope was first launched, there was an error in the mirror shape of 2.2 thousandths of a millimetre. Enough to make it almost useless. They had to send astronauts up to fit it with spectacles so it could see clearly and produce the fabulous images we are used to. In a typical 150 mm wide mirror for a basic reflecting telescope, the greatest deviation from the perfect mirror shape will be one-quarter of the wavelength of light. About 125 millionths of a millimetre. If we scale that 150 mm mirror up to 1 km wide, the maximum error across the entire surface will be less than a millimetre. And these mirrors are produced by the thousand for consumer-grade telescopes.
It wasn’t always this way, and our ability to shape machines and devices with great precision has built up gradually over hundreds of years.
The boring part of the industrial revolution
“Mr Wilkinson has bored us several cylinders almost without error; that of 50 in diameter we put up at Tipton, does not err in the thickness of an old shilling at any part.”
James Watt
The industrial revolution depended on improvements in precision engineering. When Matthew Boulton and James Watt came to commercialise their steam engine, the biggest problem was creating a cylinder smooth and exact enough for the piston to move freely without too much steam leaking out. In 1775 they found a solution in the ironmaster, entrepreneur and innovator John “Iron Mad” Wilkinson. Passionate about the uses of cast-iron, Wilkinson constantly improved production techniques. He cut the cost of cast-iron cooking pots and made them much more widely available. He developed the first cast-iron barges, was the original driving force behind the iron bridge at Coalbrookdale, made cast iron desks, and was finally buried in an iron coffin. For Wilkinson, the answer to every problem was ‘iron’.
But it was his revolutionary work on boring out cannons that attracted Boulton and Watt. Wilkinson had developed a technique of holding the cutting piece firmly and rotating the cannon blank against it. This allowed very precise bores that made the cannons safer, longer range and more reliable. A variation of this method solved the problem for steam engine cylinders. As Watt reported “Mr Wilkinson has bored us several cylinders almost without error; that of 50 in diameter we put up at Tipton, does not err in the thickness of an old shilling at any part.” The thickness of a shilling was 2.5 mm. This unbelievable precision made the Boulton and Watt steam engine a commercial success and dramatically accelerated the industrial revolution. Wilkinson went on to take full advantage of the new steam engines in his factories and mines.
By the beginning of the 19th century Jesse Ramsden and Henry Maudslay had developed screw cutting lathes that could rapidly and reproducibly create threads accurate to 0.025 mm. One hundred times more precise than Wilkinson’s steam engine cylinders. These machines created scientific instruments and tools of unrivalled precision, and could be used to manufacture further machines of even greater precision. These were the mother and father of the machine-tool revolution. They ultimately led to the ability to pack 100 million transistors into a single square millimetre on a silicon chip.
Where am I now?
Precision in the measurement of time has also played its part. In 1707 four Royal Navy ships, under the command of the wonderfully named Admiral of the Fleet Sir Cloudesley Shovell, crashed into rocks off the Isles of Scilly. Somewhere between 1400 and 2000 sailors died, including Admiral Shovell. The wreck happened because the ships did not know precisely where they were. Latitude they had a good grip on, but longitude was the problem. The disaster led directly to the Longitude Act of 1714, that offered prizes for improved precision in measuring a ship’s longitude. The most famous winner of a prize was John Harrison. He developed a portable clock that would keep time to within 1 second in a 100 days, even aboard ship. Take a clock set to noon at Greenwich, and check the time it shows local noon at your position. You can now work out how many degrees east or west you are. Remember the earth rotates 15 degrees every hour. This was the beginning of the connection between of precise timekeeping and precise navigation.
Today, GPS satellites use atomic clocks accurate to 14 billionths of a second. A GPS receiver can use the timing signals from several satellites to work out position on the earth’s surface. Over 3 billion of us now carry a device around that can fix our position to a few metres – the smartphone. Precise location information is transforming many industries, from autonomous vehicles to precision agriculture that can precisely drill, tend and harvest crops, plant by plant.
Where next with precision?
Over the last few hundred years, we have seen dramatic improvements in precision measurement, precision in manufacturing, and precision in control. This has permeated everything we use and experience. Our current society could not exist with the level of precision that was a radical breakthrough 250 years ago. So where next?
- We can already manipulate individual atoms. This could lead to new data storage devices.
- Biological systems are capable of precise engineering on a tiny scale. Bringing biomimetic design and nanotechnology together means we can learn from nature and develop new materials and new capabilities.
- Graphene and carbon nanotubes might be a route to a whole new generation of computing devices.
- Quantum dots are electronic devices so small that they can hold and manipulate a single electron. They already have applications in TVs, displays and in biomedical imaging.
These are precision materials, that rely on ever higher levels of precision in manufacture and use. I don’t know what uses they will find, which high precision technologies will win and what effect they will have on our lives. But I know the search for precision is not over. Not by a long way!
If you are interested to find out more about the history and importance of precision, Simon Winchester’s book “Exactly: how precision engineers created the modern world” is a fascinating and entertaining read.