WHEN the King of Prussia wanted a 30-metre-high water fountain to grace his palace gardens back in the 1700s, a bungling team spent a decade trying to make the dream come true, and failed miserably.
The blame for this grand failure has generally landed squarely on the shoulders of Leonhard Euler, a genius mathematician who helped with the project and is still famous today for his equations on fluid flow and spinning tops.
Historians say his grand theories fell apart when put to the practical test, and hold him up as a prime example of how theoreticians of the time didn鈥檛 understand the real world. But by trawling through letters and documents sent by Euler, physicist Michael Eckert from the Deutsches Museum in Munich concludes that this is completely unfair 鈥� Euler wasn鈥檛 to blame at all.
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King Frederick the Great wanted a fountain at his Sanssouci Palace in Potsdam that would shoot water higher than anyone had managed before. His technicians designed a windmill-powered pump to lift water to an elevated reservoir, which would then feed the fountain. But the wooden pipes they used kept bursting. During this time, Euler sent letters to the king advising on the best way to construct the fountain, and he has been blamed by critics for failing to predict how strong the pipes would need to be, and for not taking friction into account when calculating how fluid would flow within them.
Eckert says this is wrong. He has found calculations within Euler鈥檚 letters proving for the first time that the pressure in a pipe is not just created by the weight of the water in the reservoir above, but is increased by the water鈥檚 movement down the pipe. So of course the pipes they were using would burst. Euler told the king the pipes needed to be much wider, as short as possible, and made of metal rather than wood (Archive for History of Exact Sciences, vol 56, p 451).
Euler also recommended that engineers should carry out tests before starting construction to see how different types of pipe would hold up. That was the best anyone could do 鈥� even today鈥檚 physicists can鈥檛 accurately quantify such effects from first principles, Eckert points out. But the king ignored the advice, and later blamed Euler for the fountain鈥檚 failure. It wasn鈥檛 until 1841 that the fountain was successfully built under another king 鈥� using wider, metal pipes. 鈥淩ather than blaming Euler, a much more plausible cause of the bungling in the Park of Sanssouci was the king鈥檚 stinginess,鈥� writes Eckert.