They attached a cable to the balloon, and released it. The balloon and instrument were immediately sucked into the swirling vortex and disappeared.
After a several minutes, they decided to retrieve the balloon. Despite some difficulty they succeeded in bringing the balloon back to earth and checked the instruments and were stunned by the readout on the chronometer. It displayed a date, January 27, 1965.
Read more about it here: http://www.eutimes.net/2011/04/deadly-time-vortex-appears-over-antarctica/ The next link is scientific research from Brown University on technical data about the vortex. http://www.cfm.brown.edu/people/sean/Vortex/
Time travel tornado? Weird. Whether there have been any more studies on it, I don't know. But I'm sure whatever government is in charge of that portion of Antarctica, is all over it. Who wouldn't want a time machine?