Yeesh - you should be able to build one of those quite easily. A
simple tipping bucket arrangement that dumps the water until it fills
and then flips over to direct the water into the tank should do the
trick...
-- Brett Lymn, Computer Systems Administrator, AWA Defence Industries
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"It's fifteen hundred miles to Ankh-Morpork" he said. "We've got three
hundred and sixty three elephants, fifty carts of forage, the monsoon's
about to break and we're wearing ... we're wearing ... sort of things,
like glass, only dark... dark glass things on our eyes..."
- Terry Pratchett "Moving Pictures".