356 On the Construction of Buildings 
feet, so far as direct reflection is concerned; but, as we have al- 
ready observed, in the case of the recitation rooms at Girard Col- 
lege, which come inside of these measurements, the reverbera- 
tion may yet be very great. 
The Melodeon at Boston is imperfectly ellipsoidal in shape, 
with smooth walls and ceilings. Its length, width and height 
are, respectively, 1133, 57 and 35 feet. In the centre of the 
The proportions, as well as the form of a music room, are not 
a matter of indifference. We have already noticed the tendency 
of one vibrating body or medium to throw another, in con 
or in its immediate vicinity, into a similar state of vibration. In 
this way the oscillations of the contained air of a room, commu- 
“ nicated to its walls, produce therein a sympathetic vibration, 
which will be more or less perfect according as the structure 
these walls, their subdivisions and general relations of length, 
width and height, approximate to the acoustic conditions requ! 
From this comes resonance, as we understand, the existence of 
which, to a considerable extent, in some rooms gives to the voice 
that peculiar brilliancy and resilient power which every singer 
must have noticed. 
The experiments of M. Savart on the sonorous vibrations of 
solids are interesting in this connection, as showing the nature 
resonance and how the original sound is thereby intensii’s 
whether the resonant body is in actual contact with that wl 
cing the primary sound or not.* A ready illustration may be © 
tained by singing a note in the vicinity of a large drinking glass; 
and in the still more familiar experiment of speaking inside the 
mouth of a barrel. In both these cases the solid materials are 
put in vibration and impart a peculiar quality as well as intensity 
‘tothe tone. Instances are on record where glasses ave hat 
broken in this way, by a powerful voice. To satisfy oneself tha 
the vibrations are thus communicated in a well-constructed musi 
room, it is only necessary to place the hand upon the walls doe 
the performance of a symphony or chorus, and they may 
ubibhed mr he ee Savart to the-Roysl: Academy of Sclenoes.of Pa 
in the Annales de Chimie ; Waren OF go Encye. Metrop. for cope 
