Beginning at a point in the middle of the main channel of the Mississippi River, where the prolongation east of the township line between townships fifty-one and fifty-two would intersect the same; thence west with said township line to the northeast corner of township fifty-one, range three, west; thence south with the range line between ranges two and three, west, to the southeast corner of said township fifty-one, range three, west; thence west with the township line between townships fifty and fifty-one to the southwest corner of township fifty-one, range four, west; thence in a direct line to the southeast corner of section sixteen, in township fifty-four, range five, west; thence in a direct line to a point on the Mississippi River, where the line between townships fifty-five and fifty-six strikes the Mississippi River; thence east on a prolongation of said line to the middle of the main channel of the Mississippi River; thence down said river, in the middle of the main channel thereof, to the place of beginning.