AtoZ blogs: K is for… Kelvin

Consultant David Jesson celebrates an engineering icon – William Thomson, 1st Baron Kelvin.

In physical science a first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.

William Thomson, 1st Baron Kelvin, 'Popular Lectures and Addresses', Vol. 1, 1891

Consultant David Jesson celebrates an engineering icon – William Thomson, 1st Baron Kelvin

Of all the possible scientists and engineers who could have snuck into this A-Z of asset integrity, we’ve somehow limited ourselves to just the one. But what a one! Lord Kelvin’s contributions to a range of scientific disciplines are hard to quantify – they haven’t all stood the test of time, but when you are a professor from the age of 22, it’s inevitable that there will be a few failures in your research.

Kelvin sneaks in, in part because he was a professor at the University of Glasgow for 53 years; Frazer-Nash is proud of the connection to the city where our Scottish office is based. Today, he’s probably best known for his determination of ‘absolute zero’, and the temperature scale named after him. Different people will pick up on his other successes, dependent on their interests: his work on thermodynamics for example, or perhaps his contributions to the first transatlantic cables (where he first demonstrated his abilities as an engineer, and not just a scientist).

As a physicist-engineer, his interest in measuring things more accurately led to a great many innovations, including a marine compass that was much more accurate than anything previously available. However, on a personal note, I’m most interested in his development of the first strain gauges based on the changes in electrical conductivity arising from tensile loads applied to copper and iron wires. These give rise to the strain gauges that are used today, whether it be for the determination of mechanical properties of test pieces, or for monitoring the performance of structures to determine residual capacity with degradation.

If you look in the catalogue of a strain gauge supplier, you will typically see hundreds if not thousands of variations suitable for application to different materials, in different environments. But they are all based on the fundamental work of William Thomson, 1st Baron Kelvin.

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