Shoreham Airport is in the news but not many people will know the use of an oddly shaped building there.

You can see it just west of the traffic lights on the A27 by the junction to Lancing College. It is shaped like a half sphere - the top of a huge ball.

It was built in about 1942 and called a Dome Teacher, housing equipment to teach anti-aircraft gunners. Until then, realistic training required gunners to fire at a target towed behind a small plane, which removed pilots and aircraft from more important duties.

The Dome Teacher provided an ingenious substitute by projecting pictures on the whole internal wall of the sphere using a modified 35mm cinema projector.

In the centre was a Bofors AA gun. Films showed aircraft flying towards or past the trainees, who had to identify the plane as friend or foe. If it was an enemy aircraft, they would train the gun, aim ahead to allow for the aircraft's movement while the shell travelled towards it, then fire.

The clever part was the way to check that gunners offset their aim correctly. The film showed a yellow dot at the place where the aim should be for a hit but the gunners wore tinted spectacles and could not see that spot.

The instructors could see both the yellow dot and a white spot projected from the gun barrel. If these coincided, the gunners had it right.

The equipment was difficult to maintain but it was a comparatively inexpensive way of training.

I never heard if gunners who trained in this way found it as effective as the designers intended and would be interested in hearing from any.

-Peter Jones, 3 Alfriston Court, Chyngton Road, Seaford BN25 4HE, pjones9912@aol.com