Professor Eric Laithwaite
Professor Laithwaite was an amazing and very open-minded British scientist. His lectures at IC were standing room only. He was largely responsible for the design of the linear motor and Maglev trains. He also became fascinated with gyroscopes and his Christmas Lectures to the Royal Institution, that can be found on YouTube, are fascinating, as is the written record of the ones in 1974 published as "Engineer through the Looking Glass".
My memory of meeting Professor Laithwaite remains strong and vivid. He sounded like Eric Morecombe and was entirely approachable and funny with it. I explained my findings on sliding friction and he was not in the slightest surprised. He argued that there are extremes of impossibility but anything in between was essentially fair game. His opinion was that most physical equations are only there so that exam questions can be set. He also suggested, perhaps tongue in cheek, that the plethora of small atomic particles that were then being discovered, might be the result of rounding up errors in the maths.
His Faraday Lecture to the Royal Institution where he demonstrated some of the qualities of gyroscopes was never published and his nomination for Fellowship of the Royal Society cancelled. What a great shame. The Times obituary following his death in 1997, quoted him thus: "I thought my fellow scientists would be genuinely interested, so I wasn't prepared for the utter hostility of their reaction".
He published the figure on the left in 1967, I think associated with his first Christmas Lectures. He was discussing scaling of linear motors but noted that "friction does not scale as nicely as the elementary textbooks would have you believe". He used brass blocks, all to scale and found that the largest (heaviest) slid first following by the others in order. In his later lectures in 1974 (available on-line), which was about the time that I met him, he showed that adding some jam between blocks and planes meant that the smallest block could stand vertically and even beyond. This is of course not really just friction but involves cohesion/adhesion but his demonstrations of blocks sliding on a plane at different angles certainly showed that the commonly held belief that there is a single basic angle of friction is rather a simplification.