244,868. British Thomson-Houston Co., Ltd., Young, A. P., and Butcher, J. H. Oct. 21, 1924. Telephone instruments; diaphragms.-In a loud speaking telephone of the type employing a large conical diaphragm, the diaphragm 14 is protected by an open-work dome-shaped cover plate 25. The edge 22 of the diaphragm, which may be made of leatheroid, is gripped between a ring 23 and the edge 24 of the cover-plate 25 which may be turned down as at 28 to provide a seating for the flange 29 of a back cover-plate 31. The inner edge of the back plate is secured to a vibrator unit 11, which may be of the type described in Specification 243,063, by clamping screws 33. The vibratory member 12 is connected to the diaphragm 14 by a rod 13 which is adjustably mounted in a bushing 16. The coverplate 25 may have a removable cap 26 to facilitate adjustment of the connection between the vibratory member and the diaphragm. The magnetic system of the unit 11 may be adjusted by a nut 34. The loud speaker telephone may be connected with the axis of the diaphragm in a vertical or horizontal plane, either hanging from the ceiling or a bracket or supported by a stand or legs. As shown in Fig. 3, the instrument is provided with a handle 36 and a base 37 mounted on knobs 38 and connected to the cover plate at the front and back by stays 39.