In the days when Rathfarnham Castle was still a residence for Jesuit university students, there was a seismograph (pictured here) housed in a small building off the drive. It was the creation of Fr William O’Leary, a Jesuit scientist with an avid interest in pendulums, who had already constructed a seismograph in Mungret in 1909. He had to keep air currents and spiders at bay, since their delicate vibrations could simulate the effect of major earthquakes on the sensitive instrument. He had dreadful luck in September 1923 when his seismograph was temporarily out of order during a catastrophic (over 100,000 dead) earthquake in Japan. But his pioneering work introduced generations of Jesuit students to the rigourous measurement and technical skill required in scientific research.