CONCERT-ROOM ACOUSTICS. 19 



of the Upper Press Gallery. Instead of being wasted by 

 diffusion in the great vault above, they were stopped and 

 reflected by the velarium, but not so reflected as to produce 

 disagreeable repetition notes, just audible at particular points, 

 as the lights of the mirror reflections of the chandeliers would 

 be. 



Flat surfaces reflect radially, while concave surfaces with 

 certain curves reflect sound, light, heat, etc. in parallel lines. 

 The walls and roof of a music hall should scatter their reflec- 

 tions on all sides, and, therefore, should be flat, or nearly so, * 

 excepting at the angles, which should be curved or hollowed. 

 From the orchestra the sound is chiefly required to be project- 

 ed forward as from the singer's mouth ; and, therefore, an 

 orchestra should have curved walls and roof. 



Space will not permit a dissertation here on the particular 

 curve required. This has, I believe, been carefully calculated 

 in constructing the Crystal Palace orchestra. Viewed from a 

 distance, the whole orchestra is curiously like a huge wide- 

 opened mouth that only requires to close a little and open a 

 little more, according to the articulations of the choir, to repre- 

 sent the vocal effort of one gigantic throat. 



There is, I think, one fault in the shape of this mouth. It 

 extends too far laterally in proportion to its perpendicular 

 dimensions. The angles of the rnouth are too acute ; the 

 choir extends too far on each side. The singers should be 

 packed more like those of the Birmingham Festival Choir. 



There is an acoustic limit to the magnitude of choirs. 

 Sound travels at about 1100 feet per second, and thus, if one 

 of the singers of a choir is 110 feet nearer than another singer 

 to any particular auditor, the near singer will be heard one 

 tenth of a second before the more distant, though they actually 

 sing exactly together. In rapid staccato passages this would 

 produce serious confusion, though in such music as most of 

 Handel's it would be scarcely observable. 



Some observations which I have made convince me that the 

 actual choir of the Handel Festivals has reached, if not exceed- 

 ed, the acoustic limits even for Handel's music, and decidedly 

 exceeds the limits permissible for Mendelssohn and most other 

 composers. 



I found that when standing on the floor of the building in 

 front of the orchestra, and on one side, I could plainly distin- 

 guish the wave of difference of time duetto the travelling of 

 the sound, and in all the passages which required to be taken up 



