ACOUSTICS APPLIED TO PUBLIC BUILDINGS. 



233 



The law of Congress authorizing the establishment of the Smith- 

 sonian Institution directed that a lecture-room should he provided ; 

 and accordingly in the first plan one-half of the first story of the main 

 building was devoted to this purpose. It wan found, however, impos- 

 sible to construct a room on acoustic principles in this part of the 

 building, which was necessarily occupied by two rows of columns. 

 The only suitable place which could be found was, therefore, on the 

 second floor. The main building is two hundred feet long and fifty 

 feet wide ; but by placing the lecture-room in the middle of the story 

 a greater width was obtained by means of the projecting towers. 



The general form and arrangement of the room will be understood 

 from the accompanying drawing, which exhibits a general plan of the 

 second story of the main building. In this, Gr, F, F, represent the 

 rear, and M, M, M, the front towers. The lecture-room is 100 feet 

 in its greater dimension, and 64 feet from I to C, and 88 feet to the 

 extremity of the upper gallery F, F, The curved dotted line repre- 

 sents the front of the gallery, which is in the form of a horse shoe. 

 The dotted line in the rear tower represents the extension of the gal- 

 lery into this space. 



