How does the author's tone change over the course of the memoir, West with the Night?

Toward the end of the book Beryl began to spend more narrative space on her own thoughts and feelings, sharing with the reader her experiences as she came to the point of making a historical flight and as she made the flight. Beryl never does get overly emotional throughout her narration, but she does add such rich detail in the final chapters that the reader can feel her disappointment at having missed her planned destination at the end of her historic flight. The tone changed at this point, becoming less whimsy and more dramatic. However, the moment the flight was over, her tone once again assumes an almost cynical tone as Beryl talked about her trip home to show her father her accomplishment. Beryl has returned to the child, her father's daughter within these final paragraphs of her story.