The secret behind the antique clock of Notre Dame Cathedral.

Notre Dame Cathedral is the cathedral of the Archdiocese of Ho Chi Minh City, one of Saigon's unique architectural landmarks, and a popular destination for both domestic and international tourists. It also houses the oldest clock in Saigon.

Inside Notre Dame Cathedral, apart from the bell tower, many people have yet to see firsthand the intricate workings of the oldest clock on the cathedral's facade.

The clock face resembles a window, but inside lies a rather massive mechanism, approximately 2.5 meters high, 3 meters long, and over 1 meter wide, weighing over 1 ton. It rests on a brick pedestal in front of the vaulted ceiling, 15 meters above the ground, between the two bell towers. The clock was manufactured in Switzerland in 1887, under the RA brand.

Despite their rudimentary and old-fashioned design, the mechanisms operate quite accurately. To adjust the clock, there is a smaller clock behind the machine, larger than a typical household alarm clock. By observing this smaller clock, one can determine whether the larger clock is running slow, fast, or on time.

The small clock at the back is for keeping track of time.

The gears of the clock on the bell tower of Notre Dame Cathedral in Saigon.

The clock needed to be wound once a week, and the winding mechanism resembled a car engine crank. The clock also had a system for striking church bells to indicate the time, but this is no longer functional due to a worn-out mainspring.

Currently, the Notre Dame Cathedral in Saigon is undergoing restoration, which includes the restoration of the unique clock in front of the cathedral's dome.

According to Thanh Nien Online