22 On the Construction of Buildings 
sound produced in the same way, he states, continued for eight 
seconds. ‘To these we may add our own observations in the ob- 
noxious rooms at Girard College (before mentioned) which pre- 
sent an even and solid surface of stone internally. So also, in 
the case of the Musical Fund Hall in Philadelphia. ‘This room 
is one hundred and twenty-one feet long, sixty broad and twenty- 
five and a half high to the centre of the arched ceiling, the 
depth of the arch, four feet four inches, included. Instead of 
being plastered upon a lathing, battened in the ordinary way, it 
has a smooth, solid finish upon the face of the wail. By experi- 
ments made in this apartment, when empty, we found a reverb- 
eration of peculiar intensity, which lasted four to four and a half 
seconds: on striking the wall, at various points, a sharp, clearly- 
defined echo was returned. Experiments i in other rooms similarly 
situated, led to a like result. 
How to provide fully in one and the same structure for results 
thus seemingly incompatible is a problem not easy to be solved. 
It seems to us, however, that walls of solid wood (fir or pine 
being preferred,) are fittest for the purpose, as containing, in the 
largest measure, the conditions required. Here alone, Bathiees 
can be found united the requisites for a free admission and c 
together with its greater attendant ie in a large city, may prove 
an insurmountable objection to its us 
With a structure of masonry, means ioe be adopted to over- 
me, in some measure, the evils just mentioned (excessive re- 
verberation, &c.); and we know of no way by which this can 
e better accomplished, with the least detriment in other respects, 
than by the plan of battening and wainscoting the walls, or of 
lathing and ——. upon them, after the ordinary methods em- 
p loyed in carpentry. hus we gain a sound-surface less im- 
penetrable and unresisting than that of the solid walls, while the 
sonorous waves in their passage to the masonry beyond, find con- 
ditions as favorable to the free vibration of the whole structure as 
the nature of the case will admit. In this mode of finish, a space 
is left between the surfaces, which greatly assists absorption of 
the injurious excess of sound. A lining or sheathing merely, 
whether of wood or any other substance in immediate contact 
with the wall, not only excludes this provision but is objection- 
able, also, on the ground that it thus becomes more an integral 
part of the solid structure, destroying in greater degree that homo- 
* We would be understood here to use the expressions wai inscoting and lathing 
and plastering, i contra-distinction to a mere lining of wood or a layer of area 
— walls direct : (the profession will pardon us if we misuse their techni- 
