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XXII. — Observations on the Phonograph. By John Gr. M'Kendrick, M.D., Professor 

 of Physiology in the University of Glasgow. (With Two Plates.) 



(Read 17th February 1896.) 



Introduction. 



1. Since I had the honour of showing the phonograph to the Eoyal Society of Edin- 

 burgh, at a special meeting in November 1894, the instrument has occupied a good 

 deal of my time and attention, and I now venture to give the general results of the 

 investigation. 



2. The instrument chiefly studied has been the machine used in this country known as 

 the " Commercial Phonograph." Any records taken by myself have been obtained with 

 the ordinary apparatus forming part of the "commercial" speaker arm, but I have 

 always reproduced these with the aid of the so-called "musical " arm. The commercial 

 machine, or, to give it a better name, the English model, is so geared that the wax 

 cylinder, 6-g- inch (197 mm.) in circumference, makes two revolutions in one second, 

 while the spiral grooves described on the cylinder are ^-q inch (-§■ mm.) apart. A spiral 

 line about 136 yards in length may be described on the cylinder, and the recording 

 or reproducing point travels over this distance in about six minutes. 



3. I have also used the American model, which resembles in all essential particulars 

 the one just described, except that the grooves on the cylinder are y^- inch (^ mm.) 

 instead of ^ho (i mm -)- 



I. Resonators for Increasing Volume of Tone. 



4. By using conical resonators of considerable size, made of thin block tin, the tone 

 of the phonograph can be increased in volume, so that the sounds become audible and 

 agreeable in a large room. The use of resonators is common in America, but these are 

 of comparatively small dimensions, and, while they do not yield the volume of tone 

 obtained by those of greater size, they do not get rid of the upper partials that give 

 the peculiar character to the sounds emitted by the glass disk of the phonograph. To 

 this I attribute the preference often given by phonograph operators to the method of 

 conveying the sounds directly to the ears by flexible tubes. The latter plan no doubt 

 gives volume of tone and also faithfulness of quality, as it carries the sound to within 

 a few millimetres of the drum head, but the advantage is more than compensated by the 

 discomfort of the proceeding, and by the jarring friction noises that are obtruded with 

 painful distinctness. The largest resonator I use is of conical form, about 8 feet 



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