Here the "digitized" tracing of the lateral head X-ray is positioned on  Optical Scanning machine (OSCAR). The operator turned the X and Y dials to position the cross hairs over each "digitized" (marked off) point in sequential (1-177) order. Each point consequently was assigned an X- and a Y- coordinate data value in millimeters. The data from all 177 points constituted the "mathematical model" of the head.