Tide & Time is an exhibition at the National Oceanography Centre Liverpool. It’s free to visit and you’ll find out about how tides are and were predicted around the UK,  http://www.tide-and-time.uk/

Come discover the role Tidal Science had in turning Liverpool into a major port and the city it is today. Tide Predicting Machines are analogue computers designed to simulate the rise and fall of the ocean tide. The two Tide Predicting Machines in this exhibition – the Doodson-Légé machine and the Roberts-Légé machine – can be viewed by the public once a month. Both machines spent their working lives at predecessors of the National Oceanography Centre: the Liverpool Tidal Institute and at Bidston Observatory. The Roberts-Légé was one of two Tide Predicting Machines used during planning of the Normandy invasion in WWII.