A beautiful little working model of a Hele-Shaw pump, made by Bar Knight in Clydebank.

Bar Knight made models for the famous Clyde Model Dockyard in the Argyle Arcade, the company still exists.

This model was probably used to teach ship’s engineers – Hele-Shaw pumps are often used in ship steering gear, they’re very clever as they can pump in either direction without changing the speed or direction of the input shaft.