In Fig. 151c the construction of the gramophone reproducer is shown in section. A is the cover which screws on to the bottom B, and confines the diaphragm D between itself and a rubber ring. The portion B is elongated into a tubular shape for connection with the horn, an arm of which slides over the tube and presses against the rubber ring C to make an air-tight joint. The needle-carrier N is attached at its upper end to the centre of the diaphragm. At a point indicated by the white dot a pin passes through it and the cover. The lower end is tubular to accommodate the steel points, which have to be replaced after passing once over a record. A screw, S, working in