A curved‐crystal spectrometer has been designed with all the mechanism except the crystal and detector arms contained in a box 6×7×3½ inches. Three sets of arms are provided for focusing circles of 10‐, 20‐, and 40‐cm radius. Either automatic drive at from ½ to 8 degrees 2&thgr; per minute or manual scanning may be used. Precision‐cut commercial gears result in accurate positioning and less than 0.01° 2&thgr; backlash in the drive mechanism. Thus the spectrometer is satisfactory for use with rather perfect crystals such as quartz as well as with the alkali halides. Interchange of crystals and alignment of new crystals is simple and rapid.