The Oxford English Dictionary has been forced by an Australian scientist to change its definition of how a siphon works, after he discovered a 99-year-old error in the entry, Press Trust of India reported.
For almost a century, the dictionary incorrectly stated that atmospheric pressure, rather than gravity, is the operating force in a siphon, researchers said.
Siphon, a tube used to convey liquid upwards from a reservoir and then down to a lower level of its own accord, has been in use since ancient times. But the theory on how it works is still debatable.
Dr. Stephen Hughes from the Queensland University of Technology spotted the mistake in 2010.
In order to explore the boundary between the siphon and barometer in a hypobaric chamber, an experiment was conducted in the hypobaric chamber by Hughes. It simulated the effect of high altitude, according to PTI.
"A siphon 1.5 meters high was set up in the chamber and when the pressure was reduced to an altitude of 40,000 feet a waterfall appeared at the top, but the water flow remained nearly constant," PTI reported.
"At 41,000 feet, the siphon broke into two columns of water and, when returned to 40,000 feet, it reconnected as if nothing had happened, researchers said. Atmospheric pressure at 40,000 feet, which is more than 10,000 feet higher than Mount Everest, is about 18 percent of the sea level value, they said."
Connected by tubing, two buckets were set up with one higher than the other for the experiment. The higher bucket was returned water by a pool pump from the lower bucket.
"The fact that the water level in the upper and lower buckets is constant indicates that atmospheric pressure is not pushing water into the siphon," Hughes said
"The stable water surfaces act like energy barriers between the atmosphere and siphon. For energy to be transferred from the atmosphere to the water the water level would have to go down, since the amount of energy transferred is equal to force times distance," said Hughes.
"If the water level is constant the distance is zero and therefore no energy can be transferred," he said. Hughes said.
"If you think of a car, atmospheric pressure is like the wheels, it enables it to work. But gravity is the engine," he said. "It is gravity that moves the fluid in a siphon, with the water in the longer downward arm pulling the water up the shorter arm," said Hughes.
After the mistake was pointed out by Hughes, the Oxford English Dictionary corrected the error and removed the reference to atmospheric pressure, according to Hughes. However, he said the new entry "unfortunately remains ambiguous".
The finding was published in the journal Scientific Reports.
