The legs stand at an angle of 10 degrees on the seating, which means that the mortise has to be set at the same degree. I used a block of wood set at the same degree to guide the chisel when cutting the mortise. I started the mortise at the top of the seat at the place of a walnut traingle. I then calculated where the mortise would appear at the bottom. After the mortises were made, the legs were glued in and the mortises wedged. At the top of the seating the mortise was covered with the walnut traingle.