Eric Laithwaite, Emeritus Professor of Heavy Electrical Engineering at Imperial College, London, died on November 27 aged 76. He was born on June 14, 1921.

At the age of 76, at a time when many emeritus professors have long since hung up their gowns, Eric Laithwaite was happily working, like a schoolboy with a Meccano set, on the biggest project of his life - a huge working model of a futuristic rocket launcher. America's National Aeronautics and Space Administration had commissioned him to develop a concept worthy of Ian Fleming's Dr No - a five-mile long track to be tunnelled up the inside of a 10,000 ft mountain, hurtling a space capsule along the track and out through the summit into Earth orbit. The power was to come not from conventional rockets but from the love of Laithwaite's life - linear motors.

Eric Roberts Laithwaite was born in Atherton, Lancashire, the son of a farmer, and was educated at Kirkham Grammar School, the Regent Street Polytechnic and Manchester University. He served in the RAF during the Second World War, and was attached to the Royal Aeronautical Establishment at Farnborough from 1943 to 1946. He returned to Manchester to teach from 1950 to 1964, when he took up his chair at Imperial College, where he remained until he retired in 1986.

Ever since 1947 Laithwaite had been known as "the father of the linear motor"; however, as he constantly pointed out, he did not invent it, he simply rediscovered it. "The linear motor is no more than an ordinary electric motor spread out, but it can create a magnetic river capable of providing friction-free travel," he told 1950s television audiences.

Within a few years he had designed the world's first magnetically levitating high-speed train; and such was the force of his personality that he managed to persuade the Government of the day to back it with 5 million. A mile of track was built and a full-scale levitating locomotive tested. It was one of the last great all-British postwar investments in high-tech engineering, but it was abandoned. "He was devastated", observed the Science Museum historian Brian Bowers, "but it did not dampen his inventiveness."

For Laithwaite it was a crossroads. Having pinned his future on magnetic levitation, in his early fifties, he had to turn to other things. He threw himself into writing learned books on the linear motor and popular ones on invention; he renewed his childhood passion for butterflies (at his death he had one of the country's largest private collections of specimens); he became a familiar figure on radio and television, where his engaging enthusiasm rapidly made him Britain's best-known engineer of the day.

It was his fame, however, that was to lead indirectly to his downfall, in the eyes of many of his colleagues. As Britain's first media engineer, he attracted the interest of a small army of amateur inventors. Many popular scientists are profoundly irritated by this sort of attention, often binning what they regard as "crank" letters.

But not Laithwaite. One letter, in particular, caught his eye: in it an amateur inventor described a wheeled device which apparently contravened Newton's Third Law of Motion - it moved without any power to the wheels or any thrust. Intrigued, Laithwaite invited the inventor, Alex Jones, to Imperial College. The device Jones brought was powered by a simple gyroscope and it moved forward on Laithwaite's bench with ease.

"Alex showed me something I could not explain, so I just had to investigate it. It was sheer curiosity, like Alice following the White Rabbit," Laithwaite was to say later. He spent the next few years immersing himself in the specialised world of gyroscopes, gradually convincing himself that they did break known scientific laws, and that they might be a hitherto unrecognised source of preternatural power. So, when he was invited to give the Faraday Lecture at the Royal Institution, he knew exactly what to show his august audience.

He brought with him an array of gyroscopes - from toy ones that balanced on model Eiffel towers, to a huge 50lb one that he spun up and raised effortlessly above his head with one hand. "Look," he exclaimed to the assembled dignitaries, "It's lost weight!" Ignoring their evident shock at such a heretical claim, he pressed on to his final demonstration - two spinning gyroscopes mounted on kitchen scales, which he claimed had also lost weight.

"I thought my fellow scientists would be genuinely interested, so I wasn't prepared for the utter hostility of their reaction," Laithwaite recalled later. For the first time in its history, the Royal Institution failed to publish the Faraday Lecture that year. Laithwaite's nomination for the Fellowship of the Royal Society was cancelled. He retired from Imperial College in 1981 pretty much in disgrace.

But he never lost his fascination for gyroscopes. "None of my critics could ever explain to me how a 50lb spinning wheel loses weight," he said. He teamed up with Bill Dawson, a fellow electrical engineer and businessman, and spent the last years of his life experimenting with a variety of complex gyroscopic rigs, finally proving to his satisfaction that they could produce "mass transfer" - a brand new thrustless propulsion system. In 1993 he applied for a patent on a gyroscopic space-drive; typically, he had built the demonstration model out of his childhood Meccano set.

In September 1996, however, two Nasa scientists arrived at his Sussex University laboratory, and his life went full circle. They were looking for a new way of getting spacecraft into earth orbit, thought of linear motors, and headed straight for the world expert. "I showed them all the magic of magnetic levitation," said Laithwaite happily, "and they gave me the contract." He was working on Maglifter when he collapsed.

Although he mixed effortlessly with the high and mighty (he was a friend of the Prince of Wales - "I taught him everything he knows about science", he once remarked), he never abandoned his Lancastrian roots and vowels. He delighted in the sound of the spoken word, reciting poetry from memory with evident pleasure. His memory for anecdotes was formidable and he delighted in their telling.

He leaves a widow, Sheila, two sons and two daughters.

Reprinted from the online version of the Times (4/12/97) with the kind permission of Mike Murphy, Managing Editor, News International Internet Publishing, 1 Virginia Street, London E1 9XN (Tel 0171 782 3762)