And I had a research student, Heidy Mader, and she spent hours, patient hours looking through a microscope at these ice specimens, and turning them round and measuring the angles actually. You see, Mike Walford was a very good experimentalist and he’d set up this glaciology lab on the top floor of the Physics Department, and we bought a walk in fridge for Heidy Mader to do her experiments in. And she bought a great thick parka and sat inside, alone, in a lonely way, for hours looking through her microscope. And the temperature had to be adjusted exactly right, and measured. Well this is done with thermocouples, which are electrical devices which measure the temperature accurately. And she found that thermocouples weren’t giving reasonable answers, they were giving results which were all over the place. There was indeed electrical interference from somewhere. So we tried to trace this electrical interference; was somebody switching on a motor in the other labs, or what? And couldn’t trace it at all. And Mike Walford one day said, ‘Well let’s listen to it.’ So he put on some headphones and plugged them in, and he heard human voices. He heard, erm, communications traffic from the BRI, from the local hospital. We were on the top of a hill, and these were doctors paging each other in the corridors and sending out signals which were spoiling all our experiments. So Mike said, ‘Oh well, we’ve got to stop that. And obviously we can’t stop the paging system in the BRI for a trivial experiment like this, so we’ll line the whole fridge with silver foil and make it a Faraday enclosure,’ which means you can’t get any spurious electromagnetic waves getting in. Heidy went in, she could still get the interference. So there was one place it could be coming in, and that was the mains cable which was going in and running her apparatus. The signals were getting onto the mains somewhere between us and the BRI, and then getting into her little box which she was sitting in. So the answer to that was clearly you don’t use mains at all, you run it all off batteries inside. So we did, and it worked beautifully, and on that depended her very well known now observations on these angles inside ice.