Perspective glass

a telescope which shows objects in the right position.

See also: Perspective

References in classic literature ?
I walked towards the north-east coast, over against Blefuscu, where, lying down behind a hillock, I took out my small perspective glass, and viewed the enemy's fleet at anchor, consisting of about fifty men of war, and a great number of transports: I then came back to my house, and gave orders (for which I had a warrant) for a great quantity of the strongest cable and bars of iron.
I had found a perspective glass or two in one of the seamen's chests, which I saved out of our ship, but I had it not about me; and this was so remote that I could not tell what to make of it, though I looked at it till my eyes were not able to hold to look any longer; whether it was a boat or not I do not know, but as I descended from the hill I could see no more of it, so I gave it over; only I resolved to go no more out without a perspective glass in my pocket.
His concern, instead, is with the ways characters are represented through language; they are "shifting figures in a frame," and the play's action is the perspective glass that refracts their image.
The chapters of this book] have shown the play as a perspective glass, not just reflecting but refracting Jacobean politics through the lens of an invented British antiquity" (155).