Model of a Ventilator

Model of a fan operating as a double bellows. In the large rectangular compartment, a plank hinged halfway up the short front is moved up and down by a lever; the two halves into which the compartment is divided by the plank are thereby alternately reduced and enlarged. Air is admitted through two square vents at the front, consisting of simple valves lined with seal skin, one above and one below the hinges of the plank. Through similar valves, the air is expelled into a small front compartment, where the airflow is directed to a single outlet in a square ventilation duct leading upwards; this duct can be detached.