The hemisphere under the motor has a variable pitch, and the more vertical the angle, the faster the vehicle will be propelled. The more horizontal, the slower, based on the contact of the circumferance of the hemisphere. Pretty genius level thinking... but the amount of lost energy/ineeficiency was probably pretty high
Found on http://strangernn.livejournal.com/829704.html and no year or manufacturer is given, just that it came from France
