I remember as a kid reading about wetting strings of tied hands, as a method of Chinese torture. The string takes in water and somehow because of this CONTRACTS (rather than expanding).

Alternatively wet and dry the strings - perhaps using low cost sun collectors and surface (botanic) cooling.

These could run a motor, either directly or by tying the strings around a plastic tubing creating pneumatic pressure.

If I'm not mistaken, hygrometers [edited... thanks 8th] work on this principle.
-- pashute, Mar 17 2011

Potential nemesis Category_20Helper
It's all in the annos [normzone, Mar 17 2011]

(?) Hitler Lederhosen http://thegloss.com...uld-not-be-a-trend/
The camera does not lie. [8th of 7, Mar 23 2011]

Foot binding - a mad practice indeed. http://en.wikipedia...oot_binding#Process
Not for the squemish. [spidermother, Apr 15 2011]

Whool "felting" not "shrinking" http://wiki.answers...hy_does_wool_shrink
[pashute, Jul 17 2011]

Look like Japanese check this idea http://jacobi.fis.u...Abstracts/konno.pdf
Me read abstract. Seem like idea me. [pashute, Jul 17 2011]

Unshrinking whool http://kottke.org/0...ke-an-idiot-i-threw
[pashute, Jul 17 2011]

Toy fridge that actually cools
recent idea vaguely related [xaviergisz, Jul 18 2011]

Hmm, not sure - there are a load of different stories regarding unusual Eastern torture practices brought back by returning Colonial types, notorious for their "tall-stories" - although some of these have been corroborated by later evidence.

I've not heard of the wet-string one, but the water-drip torture or death from a thousand-cuts - (either by wrapping someone in chicken-wire and snipping off the fleshy protrusions one by one, or through public flaying) would seem to be of a similar ilk.

[edit-n.b. this is a totally off topic tangent]Unrelated perhaps, but just as icky, is the mad practice of foot-binding - which from childhood I always thought was simply the forced wearing of tiny shoes, but which turns out to be the repeated breaking and setting of the broken feet so that they are literally bent in half leaving the heel and toes are side-by side, with a hugely deformed arch inbetween.

You could use other expansion/contraction effects to drive a machine - maybe a bimetalic-strip powered bycicle, or use differing water pressures (oh, that's already been done) to drive an engine.

For even more bang for your buck, I bet there's some nanotechnology you could emply here as well to amplify heat-triggered expansion/contraction effects.
-- zen_tom, Mar 17 2011


But the interesting thing about this is that the string CONTRACTS when water is applied. I don't think energy extracted this way has been studied. It may turn out to be efficient, and in any case unexplored territory is always interesting. That's what HB is for.

// Yeah, I know, some of us see HB as a place to bash other's ideas and throw fishbones. I even have a personal fi... no matter.
-- pashute, Mar 17 2011


// hydrometers //

Hygrometers. Some hygrometers use a hair as the sensing element. Hydrometers are typically a kind of ballasted float for measuring the density of liquids.
-- 8th of 7, Mar 17 2011


Looking up the wet-ropes/wet-string /wet-leather type tortures on the internet, there are a few that state that the way it worked was that wet bindings were applied which shrank, causing the unpleasantness.

Like a jumper that shrinks in the wash, I'd *guess* that it's a one-way process where a microscopic (hence my point about nanotechnology) arrangement of fibres is altered, or changed in some way by the addition of water.

On the assumption that jumper-shrinkage is an anagolous process, you could do an experiment by shrinking jumpers in your washing machine. Step 1 would be to make a jumper shrink. Step 2 is trickier as I'm not sure you can *unshrink* a jumper by just letting it dry (it would not be so annoying when your jumper shrinks otherwise). You'd need a reversable process in order to drive a machine, so it's finding a way to reverse the shinkage that's the key element here.

// Yeah, I know, some of us see HB as a place to bash other's ideas and throw fishbones. I even have a personal fi... no matter.//

Not sure what you mean about bashing/fishbones etc - I was just commenting on your idea, I didn't vote on it, and I wasn't bashing it - just sharing my thoughts, sorry they weren't positive enough for you, but that's how it goes.

Or was that in reply to someone else's comment that's been since deleted? In which case, oops, apologies.
-- zen_tom, Mar 17 2011


Not sure about string, but with leather or hide, it is the drying that causes the shrinkage. When you re-wet it it goes soft and stretchy, so if you had a spring to stretch it out, then as it re-dried it might contract against the spring, I don't know. I would guess the same goes for string. I would also guess that each wet/dry cycle degrades the material (you are basically using the cells swelling and dessicating)
-- pocmloc, Mar 17 2011


Look at the bright side, [pashute], maybe your "personal fi..." is a potential nemesis (see link, it's all in the annos).
-- normzone, Mar 17 2011


:-) rotfl norm, thanks.

Zen, I'm the one to apologize. Here goes: Please forgive me for reading your annotation with suggested alternatives, as a contradiction to this idea.

Now to the problems:
a. Zen says it may not unshrink when dried, after shrinking caused by water.
b. Pocm says that both the torture and shrinking happen when dried and not when wet. So there is no anomaly to regular heating / cooling systems, where heating (and in this case evaporation) causes expansion, and cooling (in this case with a fresh supply of water) causes detraction.
c. BigSleep (thanks!!) gives a theory that could explain it, if the wetting is the cause for detraction.

I'll check it and get back soon.
-- pashute, Mar 21 2011


I read in 4th grade that Abe Lincoln had leather pants that shrank during a rain, leaving marks on his legs that stayed for the rest of his life. Yet none can dispute that these marks did not prevent him from going on to do great things.
-- bungston, Mar 21 2011


So that's what made him taller, and consequently an effective leader. If America were divided by the Civil War, Hitler would've won. See? The world saved by leather pants.
-- RayfordSteele, Mar 22 2011


leather weathered pants.
-- pashute, Mar 23 2011


// The world saved by leather pants //

But, but, but Hitler was Austrian, and he also wore leather pants (Lederhosen). <link>

Maybe he just never went out in the rain in them ?
-- 8th of 7, Mar 23 2011


It's an alternate form of the Butterfly Effect - "The Lederhosen Cascade" in which someone getting their pants wet contributes to socio-political upheaval somewhere halfway on the otherside of the the world. It's probably linked to the 6 degrees of separation rule, leading to the hypothesis that any Lederhosen Cascade event can always be attributed to Kevin Bacon.
-- zen_tom, Mar 23 2011


That's an interesting factoid about the Lincoln, however as much as I trust [bungston]'s authority on matters such as these, I'm not so confident in ten-year-old [bungston]. I've been trying to find a reference online to corroborate to no avail.
-- rcarty, Mar 24 2011


Wasn't he the one that couldn't tell a lie, so he Divided Gaul Into Three Parts with his Father's axe, which had three new heads and two new handles- making it very reliable, but extremely. Difficult to carry and use- thus starting the Hundred Years Civil War on Terror ?

Or was he the one with the 458 cubic inch V8 engine, and chrome bumpers?

Or was that Gerald Ford, the man who said" You can buy any congressman you like, as long as he's black? "

Although that might have been Benjamin Franklin Roosevelt, the well known inventor of the Teddy Bear.
-- 8th of 7, Mar 24 2011


Maybe Hitler wore them as a deterrent because he knew of our obsession to travel back in time and pants him.
-- RayfordSteele, Mar 25 2011


My grandfather's twin sister Reizy was killed on one of the last days of the war: When freed from a death march she was mowed down by an SS machine gun, in front of her sister's eyes. The sister Feiga was in an insane asylum in NY with constant nightmares, till she passed away a few years ago. My grandfather's father (an accomplished violinist and also a school master), mother and teenage brother were sent to one of the Auschwitz camps and were killed the day they reached the death camp in (Hebrew date: 28 Iyar) 1944 along with most of their village.

My other grandfather had a young brother who stupidly left Israel to Poland for a good job as Jewish leader (rabbi) of the town of Dubetzk. He and his young wife were both shot and killed (I'm still not sure if he had a child or not).

A total of 144 first grade family to my maternal grandparents' (brothers sisters uncles aunts and cousins with their immediate family: children and spouses) where murdered, and at least 20 more perished by starvation and sicknesses during or immediately following the war.

My grandparents almost never talked about it, and where always jolly and happy. They used to say: In Romania we didn't feel the war. Then when my grandmother passed away, we found two lists and confronted my grandfather with them.

Some of the stories reached me recently through surviving family members. It turns out that they definitely did feel the war.
-- pashute, Jul 17 2011


linksplainit.
-- pashute, Jul 17 2011


Such memories, [pashute]. The family history was impressive.

My memory is pretty fuzzy, but I seem to vaguely recall reading about something like the posted idea a long time ago, just once. It worked by the difference in string length in two loops, I think, which might be easier than making many wraps and trying to convert pressure into something useful.

It only stuck in my mind because I couldn't understand how it could work. Now, reading this and thinking about that, I say it will work.

My comparison is a string made of mesh bags with sponges in them. When the sponges expand in width, the wet segment will shrink in length. [+]
-- baconbrain, Jul 18 2011



random, halfbakery