When you refine crude oil, you get a black by-product called pitch, which looks like a sticky solid. However, two scientists of University of Queensland, Professors Thomas Parnell and John Mainstone, designed an experiment to prove that pitch is actually a liquid. They simply poured pitch into a funnel and placed a beaker under it to see if it will drip. Eight years after the experiment started, the first drop fell and it was found that pitch is a (extremely viscous) liquid. For the second drop to fall, another nine years had to pass, and by the time the third drop fell another nine years later, Professor Thomas Parnell had already passed away. This experiment began in 1927 and is still ongoing (the longest experiment in history) and so far eight drops of tar have fallen. The experiment is now recorded via a webcam for better observation, but in 2000, the eighth drop was never recorded due to a very untimely camera malfunction.