Inventor files patent for unique vehicle

In 1930, John Archibald Purves, a doctor and engineer from Taunton, Somerset, filed a patent for a unique vehicle known as the Dynasphere, a 3-meter-high monorail designed to revolutionize transportation. Inspired by a sketch attributed to Leonardo da Vinci, Purves developed two prototypes: one electric and one with a gasoline engine.

Prototype tested on English beaches

The gasoline-powered prototype, weighing 450 kilograms, was tested on English beaches in 1932, reaching speeds of 40 to 48 km/h. The machine, with its iron lattice structure, resembled more of a fairground attraction than a practical means of transport.

Design flaw causes dangerous spinning

The Dynasphere's design placed the driver inside a unit that was not fixed to the rim, allowing the cabin to "climb" along rails inside the wheel to drive its rotation. This system, while ingenious, led to a phenomenon called "gerbilling," where the driver would spin uncontrollably at the slightest braking or acceleration due to inertia.

Historical documentation of the issue

This issue was documented in a 2009 BBC Science Focus report titled Dynasphere testing on Weston beach in 1932. Improvements were made, including a model with ten wheels and a steering wheel connected to tilt gears, tested on the Brooklands circuit in 1932. A leisure version, the Dynasphere 8, was also developed for beach rides.

Modern revival of the concept

Nearly a century later, the concept saw a revival when Mark Foster set a Guinness World Record in May 2025, achieving nearly 144 km/h on a similar machine at Elvington, North Yorkshire. The Dynasphere's legacy highlights both its technical ingenuity and inherent dangers, with its design flaw of "gerbilling" remaining a notable challenge for its drivers.