Chap. 10.] Whijpsring Gallery. 449 



Reflected found may be magnified by much the 

 fame contrivances as are ufed in optics refpecting light : 

 hence it follows, that founds utered in one focus of an 

 elliptical cavity are heard much magnified in the other 

 focus. The whifpering gallery at St. Paul's cathedral 

 in London is of this defcription ; a whifper uttered at 

 one fide of the dome is reflected to the other, and may 

 be very diftinclly heard. The fpeaking and ear 

 trumpets are conftructed on this principle. The belt 

 form for thefe inftruments is a hollow parabolic conoid, 

 with a fmall orifice at the top or apex, to which the 

 month is applied when the found is to be magnified, 

 or the ear when the hearing is to be facilitated. 



The ftru6ture of the ear is one of the moft compli-* 

 cated and difficult fubjetfts of phyfiology, and it could 

 fcarcely be comprehended without fome previous 

 knowledge of the conftituent parts of the animal 

 frame ; for this reafon it will be neceffary to defer the 

 confideration of the manner in which we receive ideas 

 of found, till I come to treat of that part of the animal 

 economy which refpects the fenfe of hearing. 



word till the fpeaker has finiftied it, throws all the founds into 

 confufion. Thus the theatre at the Hay-market enlarges the 

 found very much ; but then at a long interval after the finger or 

 fpeaker. The theatre at Drury-lane, before it was altered, en- 

 larged the found but in a fmall degree; but then the repetition was 

 extremely quick in its purfuit, and the founds, when heard, were 

 therefore heard diftindlly. Dergolife, the great; mufical compofer, 

 ufed to fay, that an echo was the belt fchool-miftrefs; for let a 

 man's ownmufic be ever \o good, by playing to an echo me would 

 teach him to improve 'iX."Goldfmith y s Pbilofophy, .vol. ii. p. 201 

 204. 



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