>> OK, most of those are pretty self-explanatory. But a thermometer? 
>> Who'd have thought of making *that* out of a coil of wire?
> 
> Yeah, hmm. Some dial types use a bimetallic spring. Which I suppose is 
> essentially a coil of wire. :) sort of ... That's a stretch, though.

Ah, now, you see... the electrical resistence of a wire is proportional 
to its temperature. So by having a long *coil* of wire, you have enough 
wire for the resistence to be large enough to be measurable, and because 
it's a coil, it's all in "the same place" and should have uniform 
temperature. Compare the resistence of the test coil to the reference 
coil (constructed the same way and held at a known temperature) and 
you've got yourself an electronic thermometer. QED.

> Actually, an amazingly simple piece of technology exists in your car: 
> the thermostat that controls the flow of water to the radiator.

D. Attenborough pointed out that a large Oak tree sucks multiple tonnes 
of water out of the ground and lifts it 40 or 50 feet into the air each 
day - with no moving parts.

A fire engine does the same thing - but using a rawring diesel engine 
running on purified hydrocarbon energy. And not terribly efficient either.

The way the Oak does it is quite ingenius: IT USES THE LAWS OF PHYSICS. 
Specifically, as water evapourates out of th leaves, that sucks more 
water out of the branches - which sucks water out of the thunk, whic 
sucks water out of the ground. So it's a completely passive system, and 
it always delivers exactly the right amount of water without needing any 
control systems.

Mankind, you have been PWN3D.

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