Now, he was opposed, he was... he was... opposed to a certain extent by... by Porter, an amateur in this country who, I think... he... he was working at the Royal Greenwich Observatory and he was convinced that the shower meteors were... were moving at parabolic velocities around the sun, and then I became associated with Fred Whipple, the Smithsonian, and I... I think at that time he was fairly neutral about it. We had one of those early conferences in Manchester, arising from this work at Jodrell Bank and there's one... one occasion when at Jodrell Bank an enormous argument was taking place between Whipple and Öpik and Whipple turned to me and said, 'Well, if you can measure the velocity of meteors, you have a... a perfectly clear case of making a decision which has no ambiguity', and so we set about doing that.

Now, the first successful measurements using the Fresnel zone method was made, not on the shower meteors, but on the Geminids meteor shower, one December and with JG Davis and Mary Almond, who was one of my first girl research students at Jodrell, we set ourselves a task of studying the... the velocity of the stradic meteors. The... the situation was this, that if the... the movement of the... the rotation of the earth, movement of the earth in orbit around the sun, if it... if it... you meet a body in space, a interstellar space, then the maximum of loss you can get is if you were looking at the apex of the earth way in which the... the velocity you would record would be the velocity of the rotation of the earth, plus the velocity of the earth in the solar system, which amounts to 72 kilometres per second. Therefore, any meteors, which have velocities of greater than 72 kilometres per second, must be moving in hyperbolic orbits, but if there are no meteors of losses of greater... of less... of greater than that, then they must be all combined in parabolic losses around the sun. And similarly, if you directed your observations, your... your aerials or beam of the radar to the... antapex of the earth's way, then you would get the... the maximum velocity would be the difference between the velocities through the solar system and the rotation of the earth. Well, we simply did that.

We... we set about a considerable series of measurements in which we directed equipment of various sensitivity, first of all, into the apex of the earth's way and then into the antapex of the earth's way, measured velocities of many thousands of sporadic meteors. The results were pretty conclusive. We... we had no evidence whatsoever of any hyperbolic losses or of... of any meteors moving at a velocities greater than 72 kilometres per second. We began publishing this work in a series of papers, I think, the monthly notices and then it was pointed out that our greatest criticism made of us was that we were recording only visitors, meteors of considerable magnitude and so we dealt with that by... by using another radar equipment, I think this time, on a wavelength of eight metres in which we had a greater sensitivity. And I think we ended up after several years, in measuring the losses of sporadic meteors of up to magnitudes which we estimated to be plus eight, so we reached a definite conclusion that at least down to that magnitude, all the sporadic meteors must be in parabolic, moving in parabolic velocities around the sun. Well, Öpik... he made several objections, but I don't think they were... they were real and I... and I do not know what happened. I... I... presumably, if you... if you had enough sensitivity to get down to very faint mangnitudes, then... then there must be dust from interstellar space, but at least all the meteors that had so far been observed and which were visible and just below the... the visible limit, down to a magnitude of plus eight, were confined to the solar system moving in parabolic orbits around the sun.