James Dyson's uphill water feature has been the striking image of this year's Chelsea Flower Show. But how did he do it?
What a shower
It certainly beats your common or garden water feature.
Inventor James Dyson, he of the bagless vacuum cleaner, has stolen the headlines from the gardeners at this year's Chelsea Flower Show with his "Wrong Garden".
A set of four glass ramps positioned in a square clearly show water travelling up each of them before it pours off the top, only to start again at the bottom of the next ramp.
It is a sight which defies logic, and has become probably the most memorable image of this year's show.
Mr Dyson says his inspiration was a drawing by the Dutch artist MC Escher (he of Gothic palaces where soldiers are eternally walking upstairs, and of patterns where birds turn into fish).
"One of these is an optical illusion that shows water going uphill and round and round the four sides of a square perpetually," he says [see Internet Links]. "I wanted to create a series of cascades that are all on the same level - an everlasting waterfall."
After much head scratching and experimentation, the effect has been achieved. Derek Phillips, the Dyson engineer who spent 12 months building the feature, told BBC News Online that his head was spinning when he was given his brief.
"James came up to me and said he wanted this idea to make water go uphill. My initial reaction was to look for Paul Daniels' phone number. But I've had to become a bit of an illusionist myself."
How is the illusion achieved?
Covering the ramp is a glass surface. Water is pumped in at the bottom, and comes out of the opening at the top. At the opening, some of the water is diverted back down the ramp, covering the glass in a thin layer of water.
Compressed air is also pumped in where the water enters - bubbles then travel up the ramp to the opening. These bubbles, combined with the thin layer of water going downhill, are what create the illusion that the surface of the ramp is not just a glass lid.
It is a trick which has greatly intrigued the crowds at the Chelsea Flower Show, where Dyson's work is part of the Daily Telegraph's Silver Gilt award-winning garden. People have been queuing up 10-deep to see the fountain, says Mr Phillips, many of them discussing their various ideas as to how it works.
"I stand a discreet distance away and listen to some of their theories - there are some fantastic ideas there, some of them I actually wish I could make.
"One person was saying that they thought the water was actually travelling the other way - they were wondering how I was managing to get a water jet to shoot up to the top of the glass."
So could the uphill feature become a common sight around the country, either in people's gardens or as features in public squares?
No sooner has it got to the top than it starts again up the ramp
"We could certainly make mini versions of it - or even larger versions," says Mr Phillips. "I've had a few architects coming up to me asking me about it. But I'm not telling exactly how I achieve the effect."
Before someone tries to market their own uphill water feature, they had better be warned. James Dyson - no stranger to court battles over patents - has presumably taken care of the necessary legal business.