In the single crystal method developed by Bragg, the single crystal is mounted on a platform. The platform (and the mounted crystal) can be rotated in four different circles along four axes so that the diffraction pattern from every plane of the crystal can be observed in the detector. In modern diffractometers most tasks such as rotating the crystal, analyzing the data ( except growing the crystal ! ) are automated and controlled through computer programs. The schematic diagrams of the powder diffractometer and the single crystal diffractometer are shown in Figures 18.1 (a) and 18.1 (b) respectively.