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[Bill Jones <billj AT harborside.com>]

I first toyed with this idea when I was a kid.  Imagine that you have a 
counterweight (box of rocks) connected via a pulley to an elevator car 
(of your own design, but must be fairly sturdy).  If you could just vary 
the counterweight, you could make the elevator accelerate upward or 
downward.  If you're willing to accept some fairly strict constraints, 
it would be a vast improvement over the stairs.

First, energy is only free if it's a zero sum game, i. e., you ride up 
as much as you ride down.  It's not practical to send down an empty car 
for a load of bricks over and over.  Second, it's not easy to adjust the 
counterweight by much without something more elaborate, so the load in 
the car should always be the same.  That's no problem at all if only one 
person uses it.  It could be balanced for the heaviest person in the 
house, usually dad; mom or one the kids would have to wheel in some 
ballast (like a sand bag or something) in order to be able to disconnect 
the car from its hooks (a sort of free safety feature), after which it 
would function just as if dad were riding.

The easiest way to control the car is to have a counterweight that 
weighs just a little less than dad and the elevator car combined.  A 
smaller counterweight with a pulley of its own, and a rope leading down 
to the elevator car (passing through the ceiling), sits on top of the 
larger counterweight.  When you pull on the rope from inside the car, 
the small counterweight lifts off of the larger one, and you and the car 
become heavier than the counterweight, so you start to move down.  When 
you let go of the rope, you start to reverse direction.  You can 
probably find a way to clamp the rope to the side of the car so you 
don't have to keep pulling up on the rope.

With a system like this you can travel all day among any number of 
floors, and stop on a dime.  I can even think of an easy way to make the 
counterweight slightly more variable, which can be used to smooth out 
the ride or accommodate packages or loads of veggies.  You could just 
have a tank of water on the counterweight and one attached to the car, 
with a long slackened siphon hose between them.  By pumping water up to 
the counterweight, you can make the elevator lift a larger load on 
command, with absolutely no fancy hardware of any kind.  The thing that 
really makes this worthwhile is that any water pumped up does double 
duty, changing the amount of upward force by twice the weight of the 
water; that's because the weight of the car decreases by the same amount 
the the counterweight increases (or vice versa, if you've dropped off 
your stuff and are preparing to head downward).

I got a sharp stick in the eye the other day, and my recuperation has 
really left me behind with pruning Japanese plums, but they say it's 
supposed to rain on Tuesday.  Maybe there'll be more time for posting, 
but I'll believe in that rain when I see it.

Bill
S. Oregon coast