The Collaborative International Dictionary of English v.0.48:

Whereof \Where*of"\, adv.
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   1. Of which; of whom; formerly, also, with which; -- used
      relatively.
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            I do not find the certain numbers whereof their
            armies did consist.                   --Sir J.
                                                  Davies.
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            Let it work like Borgias' wine,
            Whereof his sire, the pope, was poisoned. --Marlowe.
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            Edward's seven sons, whereof thyself art one.
                                                  --Shak.
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   2. Of what; -- used interrogatively.
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            Whereof was the house built?          --Johnson.
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