Similar to modern machines, Heron’s device required inserting a coin into a slot. The coin fell onto a pan that was connected to a lever, which opened a valve on the other end where the holy water flowed out. The pan continued to move under the weight of the coin until, eventually, the coin slid off. The lever would then raise back to its initial state and close the valve, stopping the flow of water.
Dispensed in exchange for a coin.