The county of Jefferson is bounded as follows: Commencing at the northwest corner of Leavenworth county; thence south on the west line of said county, to the north line of township twelve south; thence west on said north line, to its intersection with the main channel of the Kansas river; thence up said river, in the center of the main channel therof, to the intersection with the line between the first and second tiers of sections in range sixteen east; thence north on said section line, to the corners to sections twenty-three, twenty-four, twenty-five, twenty-six, in township seven south, of range sixteen east; thence east on section lines and the south line of Atchison county, to the place of beginning.