ACOUSTICS APPLIED TO PUBLIC BUILDINGS. 221 



ON ACOUSTICS 



APPLIED TO PUBLIC BUILDINGS.* 



BY PROFESSOR JOSEPH HENRY, 



8ECRETAKT OF THE SMITII80NIAN INSTITUTION. 



At the meeting of the American Association in 1854, 1 gave a ver- 

 bal account of a plan of a lecture-room adopted for the Smithsonian 

 Institution, with some remarks on acoustics as applied to apartments 

 intended for public speaking. At that time the room was not finished, 

 and experience had not proved the truth of the principles on which 

 the plan had been designed. Since then the room has been employed 

 two winters for courses of lectures to large audiences, and I believe it 

 is the universal opinion of those who have been present, that the ar- 

 rangement for seeing and hearing, considering the size of the apart- 

 ment, is entirely unexceptionable. It has certainly fully answered 

 all the expectations which were formed in regard to it previous to its 

 construction. The origin of the plan was as follows : 



Professor Bache and myself had directed our attention to the sub- 

 ject of acoustics as applied to buildings, and had studied the pecu- 

 liarities in this respect of the hall of the House of Kepresentatives, 

 when the President of the United States referred to us for examina- 

 tion the plans proposed by Captain Meigs,, of the Engineer Corps, for 

 the rooms about to be constructed in the new wings of the Capitol. 

 After visiting with Captain Meigs the principal halls and churches 

 of the cities of Philadelphia, New York, and Boston, we reported 

 favorably on the general plans proposed by him, and which were 

 subsequently adopted. The facts which we have collected on this 

 subject may be referred to a few well established principles of sound, 

 which llave been applied in the construction of this lecture-room. To 

 apply them generally, however, in the construction of public halls, 

 required a series of preliminary experiments. 



In a very small apartment it is an easy matter to be heard distinctly 

 at every point ; but in a large room, unless from the first, in the 

 original plan of the building, provision be made, on acoustic princi- 

 ples, for a suitable form, it will be difficult, and, indeed, in most 

 cases impossible, to produce the desired effect. The same remark 

 may be applied to lighting, heating, and ventilation, and to all the 

 special purposes to which a particular building is to be applied. I 

 beg, therefore, to make some preliminary remarks on the architecture 



o Read before the American Association for the Advancement of Science, in August, 1856. 



