SABINE. — ARCHITECTURAL ACOUSTICS. 65 



gether do not emit four times the sound emitted by one. This \vide 

 separation was particularly necessary for the large pipes and the low 

 tones ; a very much less separation would have served the purpose in 

 the case of the high tones. 



From the point where the four tubes leading to the small organs 

 meet, a supply pipe ran, as shown on the drawing, to an air reservoir 

 in the room below. This was fed from an electrically driven blower 

 at the far end of the building. The chronograph was in another room. 

 The experiments with this apparatus, like the experiments heretofore 

 recorded, were carried out at night between twelve and five o'clock. 



The rate of emission of sound by the several pipes having been 

 determined, the next work was the determination of the coefficients of 

 absorption. The methods employed having already been sufficiently 

 described, only results will be given. 



In the very nature of the problem the most important data is the 

 absorption coefficient of an audience, and the determination of this 

 was the first task undertaken. By means of a lecture on one of the 

 recent developments of physics, an audience was enveigled into attend- 

 ing, and at the end of the lecture requested to remain for the experiment. 

 In this attempt the effort was made to determine the coefficients for the 

 five octaves from C2I28 to C6 2048, including notes E and G in each 

 octave. For several reasons the experiment was not a success. A 

 threatening thunder storm made the audience a small one, and the sul- 

 triness of the atmosphere made open windows necessary, while the 

 attempt to cover so many notes, thirteen in all, prolonged the experi- 

 ment beyond the endurance of the audience. While this experiment 

 failed, another the following summer was more successful. In the year 

 that had elapsed the necessity of carrying the investigation further 

 than the limits intended became evident, and now the experiment 

 was carried from Ci 64 to C, 4096, but including only the C notes, 

 seven notes in all. Moreover, bearing in mind the experiences of the 

 previous summer, it was recognized that even seven notes would come 

 dangerously near overtaxing the patience of the audience. Inasmuch 

 as the coefficient of absorption for C4 512 had already been deter- 

 mined six years before in the investigations mentioned, the coefficient 

 for this note was not redetermined. The experiment was therefore 

 carried out for the lower three and the upper three notes of the 

 seven. The audience, on the night of this experiment, was much 

 larger than that which came the previous summer, the night was a 

 more comfortable one, and it was possible to close the windows during 

 the experiment. The conditions were thus fairly satisfactory. In 

 order to get as much data as possible and in as short a time, there 



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