[Godfrey] Hounsfield got a Nobel Prize with Allan Cormack; Allan Cormack's the South African who preceded me. In my last year in Cape Town, my grant had run out, I was a Junior Lecturer in Physics in Cape Town for one year, the years '48 and '49; I came to Cambridge in the autumn of '49. Cormack lectured in medical physics as did I. Now, medical physics meant... really there was a course for nurses and various medical technicians. And you had to teach various things like lighting and simple things like that. I remember having to teach negative numbers and so on, all very... all very elementary. And... but Cormack, because he was lecturing and we had to do medical radiology, we had to explain about X-rays and penetrating and what you did when you took an X-ray, and where X-rays came from; it was all very elementary. And Cormack, in those days began thinking about... thinking about couldn't you do any better in the ordinary X-ray picture; he already knew about tomography, he was in touch with people in Sweden about it.

[Q] Yes.

Friends in Sweden... so he tried to develop a method of doing imagery construction in which he introduced some mathematics which involved what Tony and I called, peeling the onion. He tried to use Chebyshev's polynomials a bit of mathematics where you're trying to produce the mathematics describing the... not by three-dimensional lattice but by a series of shells, concentric shells. And you can do a... a kind of math... but, the mathematics wasn't correct Chebyshev's polynomials. But he did work hard and he did try to push the idea of three-dimension reconstruction. So he got the Nobel Prize together with... together with Hounsfield. I think it may have been partly his friends in Sweden, but, he certainly had... tried and he tried to do this on the map, he was quite well in with the Swedes... got to the School of... X-ray Analysis ... sorry, of X-ray Radiography. Now, the thing about Cormack is that, when I was in Cape Town I used to be a rock climber, weekends on Table Mountain, we used to go up on the rock, it was marvellous. Let's say we could ride on a bicycle to the foot of Table Mountain, the Bridal Path, it's 2,000... it's 3,000 feet high, but, you start at about 1,000 feet. And so I was... I wasn't a very serious rock climber, I would do what they would call B&C climbs. But an A climb was on ropes and Cormack was a pretty skilled mountain climber, I was friendly with him. He was ahead of me, he's older than me and so we went up Africa Face, which is one of the... and I came off the... he was ahead of me, he belayed me and I... I went out into outer space. And he held me, thank goodness, and he saved my life. But then, of course, you could argue the fact, if I hadn't have gone up with him I wouldn't have been in danger. In any case, that's Allan Cormack, he later... he had been... he'd been to Cambridge ahead of me but he worked with Frisch, a Physicist, and he came back to Cape Town. And that's where he went on doing the... he did this work in Cape Town.

[Q] Yes.

He did, he produced phantoms. The mathematics he developed did work up to a point, so he was able to produce the reconstructions, image reconstructions of things like cylinders of different density.