RESEARCHES IN SOUND. 

 FiK. 11. 



539 



yat j^in. gin. 



^>->^ 



horizontal sireu. The steamer first proceeded along the line C a nearly 

 in the direction of the axis of the horizontal trnmpet. For the distance 

 of the first three miles the horizontal trumpet was the louder. At the 



Fig. 12. 



point a, four miles distant, the two were distinct and very nearly equal. 

 At b they were distinct, also very nearly equal, the vertical perhaps a 

 little more distinct. At c very nearly equally distinct. At d the verti- 

 cal sireu was decidedly more distinct just before entering the ojitical 



