CHAPTER XVI. 



ACOUSTICS (Continued}. 



THE TOPOPHONE THE MEGAPHONE THE AUTOPHONE THE AUDIPHONE 



THE TELEPHONE THE PHONOGRAPH THE MICROPHONE. 



WE propose in this chapter to give as shortly as possible a description of 

 the various instruments lately come into use, by means of which, and electricity, 

 sounds can be carried from place to place, and their locality identified. It 

 is only within the last few years that these wonderful inventions have come 

 into use, and in a measure superseded the at one time invincible electric 

 telegraph. The Telephone is now in daily use in London and other places, 

 and its novelty, if not all its capability, has been discounted. The Phono- 

 graph has also been frequently seen. So we will on this occasion commence 

 with the TOPOPHONE, a rather novel instrument. 



As the name indicates, the TOPOPHONE is an apparatus for discovering 

 the position of a sound, from the Greek words signifying a " place " and 

 " sound." The sources of sound can be found by it, and indeed this is its 

 actual and practical use. It is claimed for this new apparatus that it stands 

 in the same relation to the sailor as his old and trusty friends, the compass 

 and sextant. These in navigation inform the steersman as to his course, and 

 tells him his position by observation. The Topophone will tell him whence 

 a sound arises, its origin wherever it may be ; and this in a fog is no 

 mean advantage. Suppose a ship to be approaching a dangerous coast in 

 a fog. We are all aware how deceptive sounds are when heard through such 

 a medium. We cannot tell from what precise direction the horn, whistle, or 

 bell is sounding. The Topophone will give us the exact spot, and we can 

 then, from our general knowledge of the locality, work our vessel up the 

 river, or into the harbour, in safety. 



The Topophone was invented in 1880, by Professor Alfred Mayer, an 

 American, and is based upon the well-known theory of sound waves. These, 

 as we have already explained, exist in the air; and if the theory of sound 

 waves has perfected the Topophone, we can fairly say that it has confirmed 

 the supposed form of the sound waves. " Sound," says the inventor of the 

 apparatus, "is supposed to be a particle continually expanding in the air, 

 composed of a wave produced by compression, and followed by rarefaction. 



