He follow'd through a lowly arched way, Brushing the cobwebs with his lofty plume, And as she mutter'd "Well-a---well-a-day!" He found him in a little moonlight room, Pale, lattic'd chill, and silent as a tomb. "Now tell me where is Madeline," said he, "O tell me, Angela, by the holy loom Which none but secret sisterhood may see, when they St. Agnes' wool are weaving piously."
Just like that, our nurse has a name: Angela. What do you think of the fact that the two old, frail people we've seen so far (Angela and the Beadsman) both have names (or titles, in the case of the latter) that identify them with Christian devotion? (Angela is derived from the word "angel.")
Angela's brought Porphyro into a room that, despite being inside the castle, feels a whole lot like the chapel outside that we saw in the first three stanzas: Poor lighting? Check. Cold? Double check. Quiet? Oh yeah—"Silent as a tomb."
In fact, just for good measure, all of the life we saw in the ballroom has been sucked out of this one room. Also, just so you know, the word "as"—just like the word "like"—tells us that there's a simile at work here.
Porphyro cuts straight to the chase: he wants to know where Madeline is.
Two things: first, the "holy loom" refers to one of those St. Agnes' Eve rituals we talked about earlier (the one where you have to spin the wool of an unshorn lamb). Second, we now know that Porphyro is definitely in the know about what day it is, and what it could mean to Madeline.