Compare Or Like The Sun-Flooded Silks Of An 18th Century Boudir
"Or like the sun-flooded silks / Of an eighteenth-century boudoir." This is a metaphor. Sun-flooded silks is a soft and elegant material. By comparing the lady with it, I think that speaker means this lady is very graceful. Also, an eighteenth-century boudoir appear a long time, even in Lowell time. Therefore, I think she means that the lady is quite old. Moreover, she is also very luxurious because that is what an eighteenth-century boudoir are like, since they are only available for rich people in the 18th century. Since I didn't put a picture of a 18th century boudoir, I put a laces for the lady to tie her hair instead because it give me a noble feeling, like the 18th century boudoir.