212 Proceedings of the British Association for [Sept. 



understood. He gave one instance of ihe sound of artillery 

 having been heard at the distance of three hundred miles, 

 and volcanic explosions at a much greater distance. He 

 recommends that the floors and walls of all large rooms, like 

 the house of commons, where it is necessary to preserve the 

 tone and enunciation of the speaker, should have their walls 

 concave within, with inclined sides, and as low as possible, 

 so as to diminish the reflection of sound or echo, and made 

 as rough as possible, by ornaments or other means. He 

 stated an example of the benefit of studding walls, and 

 covering them with canvas. He illustrated his doctrine by 

 reference to the choir of St. Patrick's Cathedral, in which 

 the enunciation is extremely clear. The disadvantages of 

 the Rotunda for public speaking were explained, as well a& 

 the cause of the sensation felt by a person who endeavours 

 to speak exactly in the centre of the room. Several obser- 

 vations were made by different persons illustrative of the 

 author's views, from all of which it followed, that the lower 

 and rougher the walls, the less their effect in injuring the 

 intonation. Hence, the propriety of fluting, or fretting 

 walls of rooms intended for public meetings ; and, for the 

 same reason, the floor should be also roughened by car- 

 peting, or sand, or turf mould, or saw dust, or some such 

 material, which would, as it were, absorb the sound re- 

 flected from the ceiling, which would be made to act as a 

 sounding board, to give " body" to the voice. The air 

 should be preserved in an equable state and currents avoided; 

 pillars are not injurious. His views appeared to be very 

 generally approved of. 



Professor Stevelly mentioned a curious echo in Trinity 

 College, Dublin, from iron palisades. Mr. Addams and 

 Dr. Reid in reply said, the great principle was to avoid re- 

 flection in sound. Mr. Addams mentioned cases of the 

 utility of pilastres and other breaks. 



1 1 . Mr. J . Russel gave a short account of his experimental 

 researches into the laws of the motions of floating bodies. 

 He detailed experiments on two canals in Scotland. He 

 shewed that small models are not applicable for exhibiting 

 the resistance of large vessels, the distinction between the 

 conditions of a floating and an immersed body, with the dif- 

 ferences from any theory, and that resistance diminished with 



