What are these rays like?

You can't see them or feel them -- any more than you can see or feel an X-ray. But when you get an X-ray treatment or have an X-ray picture taken, the rays are there all right. So are the rays of the atomic bomb.

The bomb gives off the rays at the moment it explodes and for some seconds afterward. The danger from them lasts about 90 seconds. Then they are gone. If you are a mile and a half or more from the bomb, the rays are usually harmless.