Beginning in the middle of the main channel of the Missouri River, at a point where the prolongation north of the range line between ranges fourteen and fifteen would intersect the same; thence in a direct line to the southeast corner of township forty-six, range sixteen; thence south with the range line between ranges fifteen and sixteen to the southeast corner of section one, township forty-five, range sixteen; thence west with the subdivisional lines to the southwest corner of section six, township forty-five, range nineteen; thence north with the range line between ranges nineteen and twenty to the northwest corner of township forty-eight, range nineteen; thence in a direct line to a point on the south bank of the Missouri River where the range line between ranges eighteen and nineteen terminates; thence north to the middle of the main channel of the Missouri River; thence down such river, in the middle of the main channel thereof, varying, however, therefrom, so as to leave the first island below the city of Boonville, in Howard County, to the place of beginning.