"For speculation turns not to itself
Till it hath travell'd and is married there
Where it may see itself."
I see no reason for adopting, as some do, mirror'd of Collier's and Singer's folios. There was, I believe, no such verb at that time. I prefer arrived, which could easily have become married in a printer's mind.
"Where they are extended; who, like an arch, reverberate."
Rowe read which and 'reverberates,' of which the first is needless, the second may be right.
"By an act that very chance doth throw upon him."