Letter to the Editor: A slower yet greener way to travel

A simple football floating downward like a bubble upon the surface of a descending mountain stream could well demonstrate a very green way to transport people and goods without any practical use at all of fossil fuels like coal, oil or gas. The source of energy here would be gravity.

Once this floating football has traveled several miles down a mountain it could then be placed inside a tower (filled with water) as high as the same mountain from which originally descended from and so by this means ascend back up to the same great height it had been at previously.