The automatics of Heron

Automatic opening of the temple gates  after sacrifice had taken place on its altar

Reconstruction of the invention of Heron of Alexandria, which permitted the automatic opening of the temple gates after the sacrifice on its altar.

The altar-fire warmed the air inside the container underneath and due to the expansion of gases, the air pressed the water to another communicating vessel. Through a siphon , the water was carried to a container on a balance and caused the inclination of the balance towards the container. This inclination in turn caused the rotation of the two gate axles and thus opening them. After the sacrifice, when the air underneath the altar cooled, the reverse motion of the water through the siphon caused the balance to return to its original position and thus causing the gates to close.

SOURCES: ''Heron, Pneumatics, Α 38''

Heron's (automatic) magic fountain

It was a most brilliant fountain which shot water higher than the available level of its reservoir defying ostensibly the beginnings of hydrostatic pressure.

It consisted of one open and two airtight containers placed one above the other.  The middle airtight container was full with water and a pipette began a little above its bottom and led to a nozzle above the upper open container.  When water was poured into the upper open container, this, through a pipe, flowed into the lower airtight container.  The confined air in this was pressed and through another pipe it displaced the water of the middle container, forcing it to rise to the nozzle and to shape a small spurt.  The spurt of water supplemented the water of the upper container (maintaining the level constant).  Thus this process was self-supporting and it continued automatically until all the water from the middle container emptied.

SOURCES: "Heron of Alexandria, Pneumatics"

 

The magic horse of Heron

(Horse decapitated and drinking)

It was an amazing arrangement of a horse and a herdsman that showed (by the presenter of the automaton) to cut with a knife through the neck of the horse and simultaneously this automatically continued drinking water from the cup which he held in his hand.

It consisted of a most ingenious rotating wheel that ensured the stability of the horse's head at the complete cutting off of the neck and a complicated mechanism of toothed bars and toothed sectors that separated and reconnected the telescopic pipe of the horse automatically during the severance. With the manually-operated rotation of the herdsman (opposite to that of the horse) the water from the upper container of the base of the automaton emptied into the container below causing the required vacuum in the incorporated drinking pipe of the horse and consequently the continuous drinking from the cup of water.

SOURCES: "Heron of Alexandria, Pneumatica, (78)"