In 1927 Dr. Thomas Parnell at the University of Queensland heated a sample of petroleum pitch, also called bitumen, and poured it into a glass funnel, with a sealed neck, set in a ring stand. Three years later, in 1930, he broke the neck off the funnel and set it aside. It took eight years for the first drop of pitch to fall. The experiment has been running continuously ever since, and has produced a total of eight drops to date. The man shown in the photograph above is Dr. John Mainstone, who is the experiment’s current custodian.
The most recent drop fell in November 2000, which means the next one should be falling sometime in the next couple of years. The funnel contains enough pitch to run, it is estimated, at least another hundred years. To date, no one has ever witnessed or photographed a drop falling, but that’s likely to change with the next one. The University of Queensland maintains a webcam showing a live view of the experiment at all times. The photograph below shows a screenshot I captured of it just this morning: