the officers, and the authority of training the militia according to the
discipline prescribed by Congress;
17. To exercise exclusive legislation in all cases whatsoever, over such
district (not exceeding ten miles square) as may, by cession of
particular States, and the acceptance of Congress, become the seat of
government of the United States, and to exercise like authority over all
places purchased by the consent of the legislature of the State, in
which the same shall be, for the erection of forts, magazines, arsenals,
dockyards, and other needful buildings;
--and