The Pitch Tar Drop demonstration in the School of Physics, Trinity College Dublin, became a 69 year overnight global sensation in 2013. The pitch tar was placed in the funnel in the School of Physics in October 1944, beginning what is now an 80 year continuously running demonstration. While appearing solid at room temperature, the pitch tar flows very slowly with a drop falling from the end of the funnel approximately once in a decade. The Trinity pitch tar demonstration is one of only three such experiments in the world and until the 11^th July, 2013 no one had seen a drop drip.  The University of Queensland had missed filming their drop falling in 2000. Prof. John Mainstone looked after the University of Queensland experiment for 52 years without ever seeing a drop fall. The Aberystwth University pitch-drop experiment is even older. It was started in 1914, but the pitch used is much more viscous and has not yet formed a drop. In 2013 Shane Bergin and Stefan Hutzler captured a drop falling in Trinity, becoming the first to record this rare moment. The time-lapse video  attracted global media attention including RTÉ News, the Huffington Post, the Wall Street Journal, New Scientist and the National Geographic. Discover Magazine named the Trinity Pitch Drop in their top 100 science stories of 2013 and a feature article in Nature News was the 3rd most-read piece on their website in 2013. In recognition of its global fame the pitch tar demonstration had been on display in the Eavan Boland Library since 2014 but returned to its permanent home in the School of Physics in time for the tercentenary. The most recent drop fell unobserved in 2024. We will have to wait another decade before the Trinity demonstration will drip again.

This year schools across the island of Ireland are participating in a pitch tar drop experiment. The apparatus uses a specially developed pitch tar, which has a lower viscosity than the Trinity demonstration, so we won’t have to wait 10 years for a drop to fall. In this experiment students will see a seemingly solid material flow, be able to measure the formation of the drop, calculate the viscosity and perhaps even capture that special moment when the drop falls as described in these scientific articles.

Participating Schools

This project has been developed by the following people.

School of Physics Co-ordinator: Prof. Louise Bradley

AMBER Co-ordinator: Dr. Mairead Holden

Apparatus design and construction: James McLoughlin and Patrick Murphy

Web designer and Data: Alan O’Meara

Institute of Physics Teacher Representative: Paul Nugent