Meter for hydraulic power made by Manchester Corporation Waterworks, made around 1920.

From 1894 to 1972, Manchester had a hydraulic power network. Water was pumped to high pressure and delivered to customers using a network of thick iron pipes. Massive meters capable of withstanding the high pressure of the water recorded how much water was used by each customer, so they could be charged accordingly, just like an electricity meter today. The meters were locked and only a Manchester Corporation Waterworks employee could access them.