What happened to Silas during a storm on April 27, 1858?

Silas was walking to his house when a storm arose. He took refuge beneath an oak tree just before it was struck by lighting. He was sent tumbling to the ground unconscious. His clothes were turned into cinders. His father revived him with fireplace bellows. The only last effect Silas has from the lightning strike is an image of the tree on his back.