This brief article describes an electro-mechanical 'tortoise', how it works, and the varieties of behaviour it can display. No doubt some readers have seen one of these tortoises wandering about at the Festival of Britain. It can wander in random fashion over the floor and when it meets an obstacle it sidles away. When its current runs down, it goes back to a 'hutch' where it automatically connects with charging current, and when recharged it disconnects itself and sets forth once more.