Feeds:
Posts

## James Clerk Maxwell’s statue

In May I was in Edinburgh to compete in the Edinburgh marathon. On the day after the marathon I did a sight-seeing tour of Edinburgh. One of the things I saw was a statue to the Scottish mathematical physicist James Clerk Maxwell. The statue is at the Saint Andrew Square end of George Street, abut 300 metres from the famous Princes Street.

James Clerk Maxwell(1831-1879).

The statue of James Clerk Maxwell, which is at the Saint Andrew Square end of George Street.

James Clerk Maxwell was an important physicist and mathematician. His most prominent achievement was to formulate the equations of classical electromagnetic theory. These four equations are known as Maxwell’s equations. They are shown on a small plaque at the rear of the statue’s plinth.

The rear of the statue’s plinth. The larger plaque is illustrated in the bottom photograph. Below this is a small plaque with Maxwell’s four famous equations of electromagnetism.

Maxwell’s four equations, which I have written out below.

$\boxed{ \begin{array}{lcll} \nabla \cdot \vec{D} & = & \rho & (1) \\ & & & \\ \nabla \cdot \vec{B} & = & 0 & (2) \\ & & & \\ \nabla \times \vec{E} & = & - \frac{\partial \vec{B}}{\partial t} & (3) \\ & & & \\ \nabla \times \vec{H} & = & - \frac{\partial \vec{D}}{\partial t} + \vec{J} & (4) \end{array} }$

These equations are written in differential form, where the symbol $\nabla$ is known as the vector differential operator. I will explain the mathematics of vector differential operator, and the meaning of each equation, in a series of future blogs.

The four equations can also be written in integral form, which many people find easier to understand. In integral form, the equations become

$\boxed{ \begin{array}{lcll} \iint_{\partial \Omega} \vec{D} \cdot d\vec{S}& = & Q_{f}(V) & (5) \\ & & & \\ \iint_{\partial \Omega} \vec{B} \cdot d\vec{S} & = & 0 & (6) \\ & & & \\ \oint_{\partial \Sigma} \vec{E} \cdot d\vec{\l} & = - & \iint_{\Sigma} \frac{\partial \vec{B} }{\partial t} \cdot d\vec{S} & (7) \\ & & & \\ \oint_{\partial \Sigma} \vec{H} \cdot d\vec{l} & = & I_{f} + \iint_{\Sigma} \frac{\partial \vec{D} }{\partial t} \cdot d\vec{S} & (8) \end{array} }$

The inscription on the front of the statue’s plinth. It reads “James Clerk Maxwell 1831-1879”.

The larger plaque on the back of the plinth.

### 6 Responses

1. […] wanted to get back to explaining Maxwell’s equations, which I mentioned in this blog of the statue to James Clerk Maxwell that is in Edinburgh. Before I do that I thought I would cover […]

2. I am a tour guide frequently in Edinburgh and I greatly admire this statue, but I haven’t been able to identify the circular object with a handle that Maxwell is holding. Can you help? With thanks in advance
Jon May

3. on 05/10/2014 at 13:52 | Reply marcelhendrix

I’ve allways wondered about that too!

It is probably meant to be a planimeter (Maxwell invented one), although it looks more like a circular sliderule. The planimeter Maxwell invented looks quite a bit different from the thing on the statue, though.

(Isn’t Maxwell wearing remarkably modern looking shoes 🙂

• on 11/10/2014 at 07:22 | Reply marcelhendrix

I’ve learned now that the statue shows him holding his ‘color top’, a spinning disc with colored paper, used to learn more about the physiology of color vision.

• Thanks for that info. Interesting!

4. […] with the dog, holding the disc? Why, James Clerk Maxwell, of course. You may remember him from such equations as ‘Gauss’s law’, and not forgetting his big hit ‘Faraday’s law of […]