Sentence:  I would examine the "Caſpian" Sea, and ſee where and how it <WSD>exonerates</WSD> it ſelfe, after it hath taken in "Volga", "Iaxares", "Oxus", and thoſe great rivers; at the mouth of "Oby", or where? 
Meaning of the word marked with <WSD> tags:  Of a body of water: to discharge or empty (itself).