Re: instructions
apparently there is also an odd effect with the slope of the pipes too: if they are shallowly sloped then the water can (usually) push/float "everything else" along happily, if they are steep enough (e.g. >40deg or so) then everything can slide/fall down. But there is a surprisingly big range of angles where the liquid will flow but "everything else" will just sort of sit there - hence when you see exposed drain/foul pipes on the wall of an old building they are either nearly flat or >45 deg or more...
Biting the hand that feeds IT
