There was a hint of autumn in Madison, Wisconsin before sun-up on Monday Aug. 24, 1970.
The temperature was only 49 degrees, and for those who happened to be awake at 3:30 a.m., there was unexpected cool relief from the dog days of summer.
But it was about to get hot on the University of Wisconsin campus. Searing hot.
The flame on a fuse was quietly burning down to one ton of explosive ANFO, hidden in the back of a Ford Econoline van that had been carefully parked right outside of Sterling Hall, a large university classroom building.