Further Experiments with the Gramophone

Abstract

IN NATURE of April 15 and October 21, 1909, I described various experiments with the gramophone. Since then I have made many efforts to get rid of the hissing and grating noises that detract so much from the instrument as a reproducer of musical sounds, and at last I have had an encouraging measure of success. The gramophone, as will be seen in the accompanying figure, is enclosed in a wooden cloth-lined box, and a tube passes tightly through a hole in the wall of the box from the end of the taper arm that carries the sound box of the instrument. When the sound box is tightly closed by raising and locking the front lid, as seen in the figure, the sounds of the machinery, and also the vibrations from the free side of the diaphragm of the sound box, are completely damped off. The noises, caused by the friction of the needle point on the hard disc of the record, pass, of course, along with the musical sounds, through the taper arm to the tube that escapes from the box. This tube is suitably connected with lengths of tin tubing, 1½ in diameter, and the sounds are thus conveyed through as many feet of tubing as may be found necessary. I have found the most efficient length of the entire tube, until it reaches the horn or resonator (the attachment of which is seen in the figure), to be, say, 54 feet. The effect of the long tube, while empty, is to increase the volume of the tones, but, of course, the noises are also intensified.