As is the case with most Greek tragedies, a number of different translations of Prometheus Bound are available online.
The H & P website has a link to the Perseus Project translation, by Herbert Weir Smyth.
In Smyth's translation, the first few lines are as follows:
Power:
"To earth's remotest limit we come, to the Scythian land, an untrodden solitude. And now, Hephaestus, yours is the charge to observe the mandates laid upon you by the Father"
An interesting, if somewhat old-fashioned translation, is by Henry David Thoreau.
The first few lines in Thoreau's translation are as follows:
KR.
"We are come to the far-bounding plain of earth,
To the Scythian way, to the unapproached solitude.
Hephaistus, orders must have thy attention,
Which the father has enjoined on thee,"
(In this, "KR." is for Kratos, a Greek word meaning "Might" / "Power" / "Force" / "Strength".)
Another interesting, if somewhat avant-garde and/or colloquial translation, is by "Tim Rollins and K.O.S. (Kids of Survival)". (Only the first part of this, down to H & P, line 304 [p. 583], is available online.) An idea of the modern effect that the Rollins translation aims at can be seen from the corresponding opening lines of the play, as follows:
POWER:
"And so we've come to the last stop on the train.
To Scythia: this lonely hell-hole
where no one in their right mind would go.
Hephaistos, get busy! What the Boss
demands You'd better deliver!"
In the original text, the references to Themis are in the passages which correspond to lines 15, 158, 679 (pp. 573, 578, 593) in H & P. In all three passages, Thomson omits the name "Themis". One possible reason for Thomson's doing this is that he was somehow influenced by Shelley, Prometheus Unbound (early nineteenth century), in which Themis is not mentioned, and Prometheus' mother is given simply as Earth. (For brief discussion of Shelley's play and a few excerpts from it, see H & P, pp. 1003-1004. Also, the complete text of Shelley, Prometheus Unbound is available online, as part of The Complete Poetical Works of Percy Bysshe Shelley.)
After a search of eight other translations of Aeschylus, Prometheus Bound (both hard-copy and internet), I have found no others that consistently omit mention of Themis, in the way that Thomson does. In Smyth's, Thoreau's, and the Rollins / K.O.S translations, for example, the three passages (H & P, lines 15, 158, 679) in which Aeschylus refers to Prometheus' mother are as follows:
Smyth:
"Lofty-minded son of Themis who counsels straight"
"Often my mother Themis, or Earth (though one form, she had many names)"
"Such is the oracle recounted to me by my mother, Titan Themis, born long ago."
Thoreau:
"High-plotting son of the right-counselling Themis"
"But to me my mother not once only, Themis, Gaea, of many names one form,"
"Such oracle my ancient Mother told me, Titanian Themis;"
Rollins / K.O.S (first two passages only; online version does not go as far as the third passage):
"The unstoppable son of Themis, your down-to-earth mother."
"But I always remembered what my mother Themis
(She has one form, but many different names)
Told me over and over again:"