The Man/machine interface. People who design motor cars also drive them, but whoever heard of a radar design engineer who also had a Master's ticket? Of course, the designers of marine instruments do go to sea occasionally, but not for longer than they can help; sea-time is apt to interfere with the weekend. So it happens that the people who make marine radars are rather remote from those who use them, and from the environment in which they work, the sea. The engineer might argue that no two seamen ever seem able to agree on what they want, so the easiest thing is to decide for them, and that, in any case, it is only a matter of ergonomics. On the other hand, it may be that the people who write books on ergonomics have not been to sea either. Radars are used in the dark, as are motor cars, but the darkness of the bridge is not the same as night driving.