Automatically Opening Doors – 1 AD
What is perhaps the most striking aspect of the ancient Greek’s automatic doors is the fact that it wasn’t until 1931 that the automatic doors that we are familiar with today were first created. The doors that existed in ancient Greece were clearly hundreds of years before their time. They were used only very sparingly due to the cost and time it required.
That isn’t to say that the automatic doors created by Heron of Alexandria were all that practical. They were a marvel to the people of ancient Greece but they were not something that could have been used for a home or most public buildings. It would take hours for the doors to open once the process was started. This meant that the doors could only be opened once a day.
To open the doors a fire would be lit in order to generate heat. The heat would cause the atmospheric pressure to build up in a brass vessel. The vessel would then pump water into large holding containers. The holding containers would then function as weights to open the door. This sort of hydraulic system would have been awe inspiring to those who would see a door open on its own before them.
There were two main applications for this type of door. The first was for the temple. Priests would be the ones to light the fires and keep them going to have the doors opening at the time that people would be showing up for prayer. There is also evidence that Heron developed a similar system to open the gates to the city.