Old inventions that never caught on

These old vintage inventions didn't quite make the cut.

The vintage inventions include:
Underwater propeller belt
Helicopter boat
Train cars that ride over one another
Zip lines that attach to your head
Monowheel one wheeled car (large)
Beard swim suits that keep your facial hair dry while swimming
Portable changing rooms for the beach
Car jack that uses the exhaust to lift the car
An automatic robotic lawn mower
A bicycle lawn mower
Self-launching life boats
Static electricity assisted haircuts
Monowheel one wheeled car (small)
A pedal propelled standing mini scooter
Motorized skates
Early version of roller skates
A mechanical exoskeleton for assisted walking
A motorized mechanical horse

Credit: Gizmo!