Mrs. Pritchard was to accompany me on the train that would take me on the overnight trip from Nairobi to Mombasa, where I would board the ship. For three days I had resisted wearing Valerie’s clothes, but now I had to put them on. Mrs. Pritchard herself had altered the clothes to fit me, sitting by the hour, tears dropping onto the silks and linens as she took in seams and shortened hems. Seeing her unhappiness, my dislike began to melt away.
I checked the meaning of "by the hour"on the net as every hour but in this context I think its meaning is something different.
Dose it mean: 1: She sat fitting the clothes for an hour?
2: She sat fitting the clothes for hours?
Source: Listening for Lions by Gloria Whelan