When we enter the Metrology Museum, we come across a rectangular room, in the center of which we can see the largest piece in the Museum’s collection: the Balance of the Casa da Índia (House of India).

The Balance hangs from the ceiling of the Museum and its height occupies, precisely, two floors. The plates rest on the lower floor, making it possible to observe the whole set from any of the four sides, at the Museum level, or the floor on which it rests.

This balance was built in 1803 to replace the previous one, which was lost in the context of the earthquake and tsunami of November 1, 1755.

It is a balance scale with equal arms and square shaped plates, which are attached by metal chains that start from both arms.

On the arms of the balance, on both sides, the following inscriptions are engraved: “REAL CAZA DA INDIA” and “MATHEUS ANTONIO OFES IN LISBON 1803”.

Only the currents are not original. They were incorporated in a restoration of the Balance that took place before it was presented to the public at the great National Metrology Exhibition, in 1990. This Exhibition, organized on the initiative of the Portuguese Institute for Quality, opened the Museu de Ciência da Universidade de Lisboa (Science Museum of the University of Lisbon) which is located in the old Polytechnic School building.