The Pitch Drop Experiment
from The University of Queensland
In 1927 Professor Parnell heated a sample of pitch and poured it into glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 72 years later, the eighth drop is only just about to fall.
The experiment was set up as a demonstration and is not kept under special environmental conditions (it is actually kept in a display cabinet in the foyer of the Physics Department), so the rate of flow of the pitch varies with seasonal changes in temperature. Nonetheless, it is possible to make an estimate of the viscosity of this sample of pitch. It turns out to be about 100 billion times more viscous than water!
In the 69 years that the pitch has been dripping no-one has ever seen the drop fall.