Fortunately I hadn't wasted the peanuts on a burned batch of sugar and white corn syrup, so I courageously started over. This time I stood there and watched the kettle using my eyes and nose to judge. When the wooden spoon lifted out of the hot bubbling syrup produced hard crack strings I added the peanuts and salt. In a very short time it started boiling again and soon it was ready to pour into a foiled and buttered half sheet pan.
So I am foolishly pleased about my successful attempt at peanut brittle. May cookie day with the girls tomorrow be just as successful.