This paper describes an accessory designed for a Philips‐Norelco x‐ray diffractometer to allow the investigation of the spatial distribution of any particular crystal plane found near the surface of cylindrical specimens. The device holds the specimen in the exact position required for measurement, and allows it to be moved through an arc of ±33°, while it is rotated about its own cylinder axis. Adjustments are provided for examining different regions of the specimen. It will accommodate specimens between 2.8 and 8.1 cm long and between 1.0 and 2.5 cm in diameter. Results obtained from the same thin foil specimen in cylindrical and planar form show reasonable agreement.