AN interesting addition to the phonograph or the gramophone has been designed and made by Mr. Bowron, of 57 Edgware Road. It is well known that the action of a gramophone depends on a spiral line ...

THE Cambridge Instrument Co., Ltd., has issued a new list of oscillographs developed from the Duddell type (List No. 118). As usual in the catalogues of this firm, there is a valuable discussion ...