He began these observations of the radiation from space, which had been discovered by Jansky in 1930, '31, and had really only been studied much further by Reber, in America during the war. All that was known then was that from somewhere in the galaxy, radio waves were being emitted. Hey, in his work, had located the general distribution of these radio emissions, this radio emission from space, and had indicated that there might be some specialised sources of it in the galaxy, and the only thing we knew then was that the main radiation appeared to be emanating from somewhere in the galaxy. Hanbury Brown and Hazard discovered that by laboriously slackening and tightening the stays, which held the tubular mast to the telescope, they could change the direction of the beam up to about 15 degrees from the zenith. And so, by great good fortune, the great spiral of the... in Andromeda M31, one of our nearest nebulae passed through the beam, within that region of space, and it was their work, which I must say, it was unbelievably laborious because they had to work under frantic conditions in slackening this aerial and changing it, changing the beam. But they did produce a complete map of the sky covering about plus or minus 15 degrees from the zenith. And in that gap, they isolated the radiation from the Andromeda Nebula M31. Now, this was, I believe, almost certainly, the first proof the at least some of the cosmic radiation was emanating form outside the galaxy. I think this paper was published in 1950, '51.