62 SIGHT AND HEARING. 



would be less excursive than that which we obtain 

 by smelling which does not define or even point 

 out the situation of its object at all. Thus, though 

 we may grope our way very minutely and very 

 nicely to the details of nature in the dark, we 

 should never be able to group them, or to com- 

 prehend the beauty or grandeur of nature, if we 

 had not powers of observation scarcely less limited 

 in extent than excursions of mind itself. 



Now we have two remaining senses, the one of 

 which more immediately enables us to learn from 

 nature, and the other to learn from our fellow 

 men, and yet the two work beautifully together 

 for our instruction, and, as one may say, take 

 counsel and strive together to make us wise and 

 happy. These are our sight and our hearing, and 

 so admirably are they formed that they are not 

 only more easily, and may be more extensively 

 educated than any of our other senses, but we can 

 heighten their powers by artificial means. 



The speaking trumpet augments the sound of 

 him who speaks, and the hearing trumpet concen- 

 trates and strengthens the sound to him who 

 hears ; and those who are acquainted with the 

 observed laws of sound can so manage matters as 

 that a whisper can pass silently over a crowd, and 

 be heard distinctly by a more distant person by 

 whom it is intended to be heard. Sound also 

 may be doubled and redoubled by reflection from 

 surfaces ; and it is very possible to hear one of 

 those reflected sounds when the original sound is 

 not heard. There is a very familiar illustration 

 of that. If you are in the house with equal 

 windows, equally open on all sides of it, and if it 

 thunders, or if ordnance fire, or the bell tolls, or 



