52 ACOUSTICS. 



Hearing-trumpets collect and condense the sound, and 

 thus convey it to the ear. 



Many amusing experiments and exhibitions have been 

 at various times shown, depending on the peculiar nature 

 of this branch of natural philosophy. The most striking 

 of these was that termed the Invisible Girl, and which, 

 in the beginning of the present century, was exhibited 

 at different parts of England with considerable eclat. 

 As a description of this lady may not be uninteresting to 

 the youthful reader, it is attempted ; although, being 

 given quite from memory, after a period of more than 

 30 years, it is feared that it may be, in some respects, 

 defective. On entering the exhibition-room, the specta- 

 tor saw an instrument having the appearance of four 

 brass trumpets, at right angles, communicating with a 

 brass globe in the centre, about ten inches or more in 

 diameter. This was suspended by small cords or ribbons 

 from four small pillars about one inch in diameter, with 

 a cross- rail near the top and bottom, standing unsteadily 

 in the centre of the room. The exhibiter directed the 

 attention of the spectators to the brass globe, represent- 

 ing to them that, the lady was in the inside of it, and that, 

 by addressing her in any one of several languages, she 

 would return an answer. Various questions were put in 

 English, French, and Italian, to each of which an answer 



O * 



was heard from the trumpets, in a weak, feminine voice, 

 issuing apparently from the globe in the centre - T and as 

 there was no visible communication between the globe 

 and any other thing whatever, it was at the time a source 

 of surprise how the voice was conveyed there. It subse- 

 quently appeared that a communication was made by a 

 pipe in an adjoining apartment, in which was a female 

 properly instructed ; the pipe being passed under the 

 floor, and up one of the pillars, its orifice was placed di- 

 rectly opposite one of the trumpets, and the voice was 

 thus conveyed backwards and forwards between the lady 

 and her visiters. 



