PHONOGRAPH (from Gk. ¢novh, p1/57itl, sound, voice 7pcioeLv, graphein, to write). The first mechanical device for the registering and reproduction of speech or other sound was the in vention of Leon Scott, known as the phonauto graph and constructed in 1S55. It consisted sim ply of an ellipsoidal barrel. In this apparatus the sound receiver was open at one end and closed at the other. From the closed end projected a small tube, across which was stretched a flexible membrane, to the centre of which by means of sealing wax was affixed a bristle, which acted as a stylus, and vibrated with the membrane. In front of the membrane was placed a horizontal cylinder, which was wrapped with a sheet of paper, covered with a thin layer of lampblack, against which the bristle rested lightly. :thy sound vibrations entering the ellipsoid were transmitted by the membrane to the stylus, which, when the cylinder was made to revolve, and to advance slowly, described on the lamp black surface a zig-zag line which was thus prac tically a phonographic record of whatever vibra tions had been produced.
The invcntioit el Leon tscott embodies the es sential principh on which recording and repro ducing instrument, of the present di are based. If new we substitute a receiving funnel for the cllipsoid, a inure rigid or metal stylus for the bristle, and a tin-foil covered cylinder for the lainplilack one, we the phonograph of Thomas A. Edison, as it was originally con structed in IS77; with this essential difference, however, that the sound vibrations were now indented instead of being traced. By reversing the machine—that is. causing a blunt stylus to travel over the indentations made, the original sound was reproduced. treat expectations were entertained of this invention at the time; but it was found that after a few repetitions the record became effaced from the tin foil and the invention proved to be scarcely more than an interesting toy.
During the year NS'S Mr. Edison placed upon the market a phonograph which was a far more elaborate machine as well as more practical than any of its predecessors. The tin-foil gave place to a wax cylinder, which, as shown in the illus tration, is slipped over and held on a mandrel.
The recording and reproducing devices differ slightly and are shown in the accompanying figures. In operating, the wax cylinder is made to revolve. In talking into the funnel, the malle able glass diaphragm, with a cutting stylus on its under surface, is made to vibrate, and a register of the sound is thus cut vertically into the wax, the cutting stylus advancing horizontal ly as the cylinder revolves. In reproducing. an other diapligram. which differs from the first in that it has a different tool and is made of sheets of mica, is employed. The cutting or re cording stylus consists of a sapphire with a cup shaped front which is ground to a fine edge. The reproducing stylus, on the other hand, has a ball shaped point. This stylus follows the track cut out by the recording stylus. Its motion causes the diaphragm to vibrate, and thus to reproduce the original sound. The machine gets its power from a small electric motor or spring. The sound thus reproduced is not at all equal in volume to the original, but v he strengthened by means of a funnel to a reproducer, and by adjusting the speed of the machine sounds may be given out with sufficient loudness to be heard by all in a room. In using a cylinder that already contains a phonographic record, a sharp knife precedes the cutting stylus, thus removing the previous record. A record once made can be reproduced several thou sand times without perceptible impairment of its quality, and a record made on one machine can be reproduced on another, thus ad mitting of the cylinder's being used for mailing. as in ordinary correspondence. There is no limit to the speed with which sounds can be recorded, nor to the number and variety of sounds. The difficulty of concentrating the sounds upon the diaphragm is surmounted in factories where musical and other records are constructed by grouping together the persons or instruments whose sound is recorded. By increasing the speed of the cylinder the pitch is raised, and by les sening it the pitch is lowered. See GRAMOPHONE.