The pitch drop experiment is a long-term experiment which measures the flow of a piece of pitch over many years. Pitch is the name for any of a number of highly viscous liquids which appear solid, most commonly bitumen. At room temperature, tar pitch flows at a very slow rate, taking several years to form a single drop. Started in 1927 and still running
The Pitch Drop Experiment | School of Mathematics and Physics. Custodian of the experiment, Professor John Mainstone. Pitch - brittle solid, highly viscous fluid, or both? 83 years later, the 9th drop is just forming and you can watch, live!
In 1927 Prof. Thomas Parnell, University of Queensland, poured a heated sample of pitch (most highly viscous substance on Earth) into a sealed funnel and let it settle for three years before cutting the stem of the funnel. The first drop fell December 1938. The second fell in 1947. In 2014 the ninth and most recent drop fell during a beaker exchange. A drop falls about once every decade.