Model of a Ventilator

Model of a fan working as a double bellows. In the large rectangular compartment, a plank, hinged at half height against the short front, is moved up and down with a lever; the two halves into which the compartment is divided by the plank are thereby alternately reduced and enlarged. Air is drawn in through two square vents at the front, consisting of simple valves lined with sheepskin, one above and one below the hinges of the plank. Through similar valves, the air is discharged into a small compartment at the front, where the airflow is directed to a single outlet.