Transport - One Wheel Motorcycle - Milan - 1922 - 1923 Signor Davide Cislaghi with his one wheel motorcycle called the "Monowheel" which is capable of speeds up to 40 mph. The trials have proved a success and the machine will soon be on the market.
The Dynasphere was a monowheel electric vehicle invented in 1932 by Dr. J. A. Purves from Taunton, Somerset, UK. It had 2.5 horse power and once attained a speed of 25mph - http://www.cultofweird.com/laboratory/dynasphere/