126 NATURAL HISTORY. 



they may be guided to any point : but the reflexion 

 of sounds is hard to master ; because the sound 

 filling great spaces in arched lines, cannot be so 

 guided : and therefore we see there hath not been 

 practised any means to make artificial echoes. And 

 no echo already known returneth in a very narrow 

 room. 



243. The natural echoes are made upon walls, 

 woods, rocks, hills, and banks ; as for waters, being 

 near, they make a concurrent echo ; but being far 

 ther off, as upon a large river, they make an iterant 

 echo : for there is no difference between the con 

 current echo and the iterant, but the quickness or 

 slowness of the return. But there is no doubt but 

 water doth help the delation of echo ; as well as it 

 helpeth the delation of original sounds. 



244. It is certain, as hath been formerly touched, 

 that if you speak through a trunk stopped at the 

 farther end, you shall find a blast return upon your 

 mouth, but no sound at all. The cause is, for that 

 the closeness which preserveth the original, is not 

 able to preserve the reflected sound : besides that 

 echoes are seldom created but by loud sounds. And 

 therefore there is less hope of artificial echoes in air 

 pent in a narrow concave. Nevertheless it hath been 

 tried, that one leaning over a well of twenty-five 

 fathom deep, and speaking, though but softly, yet 

 not so soft as a whisper, the water returned a good 

 audible echo. It would be tried, whether speaking 

 in caves, where there is no issue save where you 

 speak, will not yield echoes as wells do. 



245. The echo eometfa as the original sound doth, 



