Phonozoic Text Archive, Document 119


A Simple Phonograph

Scientific American XXIX:8 (August 24, 1878), p. 118.

            This simple instrument, which is shown in perspective in Fig. 1, in section in Fig. 2, and in plan in Fig. 3, consists of a mouthpiece, A, to which is attached a thin ferrotype plate diaphragm, B, by means of a good quality of sealing wax or cement. 

            Upon the outer face of the diaphragm and at opposite edges there are guides, C D, for receiving the wooden strip, F.  These guides present only a slight bearing surface to the strip.  The guide, D, is rounded to receive the spring, E, which is secured to it by two screws, by which also the spring is adjusted so as to bear with more or less force on the small rubber block which rests upon the center of the diaphragm. 

            A needle, which is sharpened like a leather sewing needle or awl, is soldered to the spring, and is located directly opposite the center of the diaphragm.  The guides, C D, are placed so that the median line of the strip, F, is at one side of the needle.  The strip, F, has four slight longitudinal grooves, two on each side, which are made with an ordinary carpenter’s gauge.  These grooves are located so that when the strip is moved through the guides, one or the other of them will pass over the needle.  A piece of beeswax is rubbed over the sides of the strip to give it an adhesive coating for receiving the foil used in recording the sounds. 

            The foil, which should be rather heavy, must be cut into strips wide enough to extend beyond the grooves in the wooden strip.  The foil is laid on the wooden strip and burnished down with the thumb nail, so that it will adhere.  The strip thus prepared is placed in the guides, C D, and the needle is adjusted so that it indents the foil slightly as the stick is moved along.
By talking in the mouthpiece and at the same time moving the strip along with a smooth steady motion, the sounds are recorded on the foil.  By passing the strip again through the guides, so that the needle traverses the same groove, and applying to the mouthpiece a paper funnel or resonator, the sounds or words spoken into the instrument will be reproduced.  It is even possible to record the sounds on a plain piece of wood so that they may be reproduced.  The engraving is about two thirds the actual size of the instrument.