In chapter 16, what does Hester learn "while attending in a sick chamber"?

Hester learned that Dimmesdale had been asked to visit the Apostle Eliot. He was a Puritan minister who preached to native Indians,

"Mr. Dimmesdale had been summoned to make a prayer, she learnt that he had gone, the day before, to visit the Apostle Eliot, among his Indian converts."

He wouldn't return until afternoon on the next day.