Stories 76, 77, and 78:

Story 76:

In his leisure, the scientist built a time machine. He went back 75 years upon its completion. He engaged in society eagerly, especially taking pride in successfully introducing his grandparents to each other. Then he remembered that his grandfather had married twice--this was the wrong wife.

Story 77:

He said he would never forgive her. "Never" ended on July 12.

Story 78:

"Father's dying."
"Not again..."