The night of the torsion balance – Interactive guided tour with the presentation of the world-famous Eötvös pendulum in the ELTE University Library and Archives

Place: University Library and Archives, Eötvös Lorand University (ELTE), 1053 Budapest, Ferenciek tere 6.

Date: November 27, 2020 at 6:00 PM and 7:00 PM

The event has been cancelled due to the COVID-19 pandemic!

In accordance with the epidemiological rules (mask wearing, hand disinfection, distance) 8-8 people can take part in our guided tours. Participation is free, but pre-registration is required. You can register at the e-mail address

The physicist Loránd Eötvös (1848–1919) focused on gravity research from the 1880s, and compared to previous instruments, Eötvös designed a much more sensitive and precise instrument, which he continuously developed with the help of his colleagues. With Eötvös pendulums made by Nándor Süss's fine mechanics workshop, Loránd Eötvös showed the identity of heavy and helpless masses (one of the foundations of Einstein's general theory of relativity) with unimaginable accuracy, measuring the change in the Earth's gravitational field by geography.

He obtained his results on the basis of field measurements, and his team examined areas of interest for gravitational changes and anomalies due to the presence of rocks of different densities, so in 30 years 1420 different parts of Europe were measured with the pendulum - from Transylvania to Italy.

One of the early versions of the Eötvös pendulum, the “Paris pendulum” made in 1898, was exhibited in the interactive exhibition “Under the spell of accuracy – The Life and work of Loránd Eötvös”. After closing our library, when the street is already quiet, it is worth watching the pendulum during operation. During the day, when the whole city is bustling, the metro trains pass under the building every minute, the thread in the pendulum, the soul of the instrument, cannot rest for a moment from the constant change. However, the city is already quiet at night, so let’s take a look at this sensitive instrument together on Researchers’ Night.

More information about the exhibition:

Join our Bach concert, which will take place on November 27, 2020 between 5:00 pm and 6:00 pm in the hall of the ELTE University Library and Archives!

Source/author of illustration: